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Mathew AJ, Finn HT, Carter SG, Gandevia SC, Butler JE. Motor-evoked potentials in the human upper and lower limb do not increase after single 30-min sessions of acute intermittent hypoxia. J Appl Physiol (1985) 2024; 137:51-62. [PMID: 38722751 DOI: 10.1152/japplphysiol.00010.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 05/01/2024] [Accepted: 05/01/2024] [Indexed: 07/11/2024] Open
Abstract
Acute intermittent hypoxia (AIH) can induce sustained facilitation of motor output in people with spinal cord injury (SCI). Most studies of corticospinal tract excitability in humans have used 9% fraction inspired oxygen ([Formula: see text]) AIH (AIH-9%), with inconsistent outcomes. We investigated the effect of single sessions of 9% [Formula: see text] and 12% [Formula: see text] AIH (AIH-12%) on corticospinal excitability of a hand and leg muscle in able-bodied adults. Ten naïve participants completed three sessions on separate days comprising 15 epochs of 1 min of AIH-9%, AIH-12%, or sham (SHAM-21%) followed by 1 min of room air (21% [Formula: see text]) in a randomized crossover design. Motor-evoked potentials (MEPs; n = 30, ∼1 mV) elicited at rest by transcranial magnetic stimulation and maximal M-waves (Mmax) evoked by peripheral nerve stimulation were measured from the first dorsal interosseous (FDI) and tibialis anterior (TA) muscles at baseline and at ∼0, 20, 40, and 60 min post intervention. AIH-9% induced the greatest reduction in peripheral oxygen saturation (to 85% vs. 93% and 100% in AIH-12% and SHAM-21%, respectively; P < 0.001) and the greatest increase in ventilation [by 22% vs. 12% and -3% in AIH-9%, AIH-12%, and SHAM-21%, respectively (P < 0.001)]. There was no difference in MEP amplitudes (%Mmax) after any of the three conditions (AIH-9%, AIH-12%, SHAM-21%) for both the FDI (P = 0.399) and TA (P = 0.582). Despite greater cardiorespiratory changes during AIH-9%, there was no evidence of corticospinal facilitation (tested with MEPs) in this study. Further studies could explore variability in response to AIH between individuals and other methods to measure motor facilitation in people with and without spinal cord injuries.NEW & NOTEWORTHY This is the first study that tests whether acute intermittent hypoxia (AIH) induces motor output facilitation in humans after two different doses of AIH (9% and 12% [Formula: see text]) and the reproducibility of participant responses after a repeat AIH intervention at 9% AIH. There was no motor output facilitation in response to either dose of AIH. The results question the effectiveness of a single 30-min session of AIH in inducing motor output facilitation, tested in this way.
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Affiliation(s)
- Anandit J Mathew
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Harrison T Finn
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Sophie G Carter
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Simon C Gandevia
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
- Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - Jane E Butler
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
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Burtscher J, Raberin A, Brocherie F, Malatesta D, Manferdelli G, Citherlet T, Krumm B, Bourdillon N, Antero J, Rasica L, Burtscher M, Millet GP. Recommendations for Women in Mountain Sports and Hypoxia Training/Conditioning. Sports Med 2024; 54:795-811. [PMID: 38082199 PMCID: PMC11052836 DOI: 10.1007/s40279-023-01970-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2023] [Indexed: 04/28/2024]
Abstract
The (patho-)physiological responses to hypoxia are highly heterogeneous between individuals. In this review, we focused on the roles of sex differences, which emerge as important factors in the regulation of the body's reaction to hypoxia. Several aspects should be considered for future research on hypoxia-related sex differences, particularly altitude training and clinical applications of hypoxia, as these will affect the selection of the optimal dose regarding safety and efficiency. There are several implications, but there are no practical recommendations if/how women should behave differently from men to optimise the benefits or minimise the risks of these hypoxia-related practices. Here, we evaluate the scarce scientific evidence of distinct (patho)physiological responses and adaptations to high altitude/hypoxia, biomechanical/anatomical differences in uphill/downhill locomotion, which is highly relevant for exercising in mountainous environments, and potentially differential effects of altitude training in women. Based on these factors, we derive sex-specific recommendations for mountain sports and intermittent hypoxia conditioning: (1) Although higher vulnerabilities of women to acute mountain sickness have not been unambiguously shown, sex-dependent physiological reactions to hypoxia may contribute to an increased acute mountain sickness vulnerability in some women. Adequate acclimatisation, slow ascent speed and/or preventive medication (e.g. acetazolamide) are solutions. (2) Targeted training of the respiratory musculature could be a valuable preparation for altitude training in women. (3) Sex hormones influence hypoxia responses and hormonal-cycle and/or menstrual-cycle phases therefore may be factors in acclimatisation to altitude and efficiency of altitude training. As many of the recommendations or observations of the present work remain partly speculative, we join previous calls for further quality research on female athletes in sports to be extended to the field of altitude and hypoxia.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Antoine Raberin
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Franck Brocherie
- Laboratory Sport, Expertise and Performance (EA 7370), French Institute of Sport, Paris, France
| | - Davide Malatesta
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Giorgio Manferdelli
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Tom Citherlet
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Bastien Krumm
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Nicolas Bourdillon
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland
| | - Juliana Antero
- Institut de Recherche Bio-Médicale Et d'Épidémiologie du Sport (EA 7329), French Institute of Sport, Paris, France
| | - Letizia Rasica
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Grégoire P Millet
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Building Synathlon, Campus Dorigny, 1015, Lausanne, Switzerland.
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Miller S, Lopez EJ, Grittner JML, Dougherty BJ. Low level CO 2 supplementation maintains isocapnia and reveals ventilatory long-term facilitation in rats. Respir Physiol Neurobiol 2024; 320:104185. [PMID: 37935342 PMCID: PMC10842720 DOI: 10.1016/j.resp.2023.104185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 10/23/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023]
Abstract
Acute, intermittent hypoxia (AIH) induces ventilatory long-term facilitation (vLTF) in awake, freely behaving rats under poikilocapnic and isocapnic experimental conditions. Establishing pre-clinical methods for vLTF induction that more closely align with successful protocols in humans and anesthetized rats would minimize dissonance in experimental findings and improve translational aspects of vLTF. Here, we tested several levels of low-dose CO2 supplementation during and after AIH to determine 1) the lowest amount of inspired CO2 that would maintain isocapnia in rats during a vLTF protocol, and 2) the net impact of supplemental CO2 on vLTF expression. Rats received one of four levels of inspired CO2 (0%, 0.5%, 1% or 2%) administered during AIH and for the 60 min following AIH to quantify vLTF. Our findings indicated that 2% inspired CO2 was sufficient to maintain isocapnia across the AIH protocol and reveal significant vLTF. These findings provide evidence-based support for using 2% supplemental CO2 during and after AIH when assessing vLTF in rats.
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Affiliation(s)
- Shawn Miller
- Division of Physical Therapy, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Edgar Juarez Lopez
- Division of Physical Therapy, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Jessica M L Grittner
- Division of Physical Therapy, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Graduate Program in Rehabilitation Science, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Brendan J Dougherty
- Division of Physical Therapy, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, MN, USA.
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Burtscher J, Citherlet T, Camacho-Cardenosa A, Camacho-Cardenosa M, Raberin A, Krumm B, Hohenauer E, Egg M, Lichtblau M, Müller J, Rybnikova EA, Gatterer H, Debevec T, Baillieul S, Manferdelli G, Behrendt T, Schega L, Ehrenreich H, Millet GP, Gassmann M, Schwarzer C, Glazachev O, Girard O, Lalande S, Hamlin M, Samaja M, Hüfner K, Burtscher M, Panza G, Mallet RT. Mechanisms underlying the health benefits of intermittent hypoxia conditioning. J Physiol 2023. [PMID: 37860950 DOI: 10.1113/jp285230] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023] Open
Abstract
Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender. Adaptive responses to hypoxia protect from future hypoxic or ischaemic insults, improve cellular resilience and functions, and boost mental and physical performance. The cellular and systemic mechanisms producing these benefits are highly complex, and the failure of different components can shift long-term adaptation to maladaptation and the development of pathologies. Rather than discussing in detail the well-characterized individual responses and adaptations to IH, we here aim to summarize and integrate hypoxia-activated mechanisms into a holistic picture of the body's adaptive responses to hypoxia and specifically IH, and demonstrate how these mechanisms might be mobilized for their health benefits while minimizing the risks of hypoxia exposure.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Tom Citherlet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Alba Camacho-Cardenosa
- Department of Physical Education and Sports, Faculty of Sports Science, Sport and Health University Research Institute (iMUDS), University of Granada, Granada, Spain
| | - Marta Camacho-Cardenosa
- Clinical Management Unit of Endocrinology and Nutrition - GC17, Maimónides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofía University Hospital, Córdoba, Spain
| | - Antoine Raberin
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Bastien Krumm
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Erich Hohenauer
- Rehabilitation and Exercise Science Laboratory (RES lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
| | - Margit Egg
- Institute of Zoology, University of Innsbruck, Innsbruck, Austria
| | - Mona Lichtblau
- Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Julian Müller
- Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Elena A Rybnikova
- Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg, Russia
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Institute for Sports Medicine, Alpine Medicine and Health Tourism (ISAG), UMIT TIROL-Private University for Health Sciences and Health Technology, Hall in Tirol, Austria
| | - Tadej Debevec
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Sebastien Baillieul
- Service Universitaire de Pneumologie Physiologie, University of Grenoble Alpes, Inserm, Grenoble, France
| | | | - Tom Behrendt
- Chair Health and Physical Activity, Department of Sport Science, Institute III, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Lutz Schega
- Chair Health and Physical Activity, Department of Sport Science, Institute III, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Hannelore Ehrenreich
- Clinical Neuroscience, University Medical Center and Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Christoph Schwarzer
- Institute of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Oleg Glazachev
- Department of Normal Physiology, N.V. Sklifosovsky Institute of Clinical Medicine, I. M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Olivier Girard
- School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Western Australia, Australia
| | - Sophie Lalande
- Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, USA
| | - Michael Hamlin
- Department of Tourism, Sport and Society, Lincoln University, Christchurch, New Zealand
| | - Michele Samaja
- Department of Health Science, University of Milan, Milan, Italy
| | - Katharina Hüfner
- Department of Psychiatry, Psychotherapy, Psychosomatics and Medical Psychology, University Hospital for Psychiatry II, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Gino Panza
- The Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI, USA
- John D. Dingell VA Medical Center Detroit, Detroit, MI, USA
| | - Robert T Mallet
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
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Panza GS, Burtscher J, Zhao F. Intermittent hypoxia: a call for harmonization in terminology. J Appl Physiol (1985) 2023; 135:886-890. [PMID: 37560767 PMCID: PMC10642510 DOI: 10.1152/japplphysiol.00458.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/24/2023] [Accepted: 08/03/2023] [Indexed: 08/11/2023] Open
Abstract
Mild intermittent hypoxia may be a potent novel strategy to improve cardiovascular function, motor and cognitive function, and altitude acclimatization. However, there is still a stigma surrounding the field of intermittent hypoxia (IH). Major contributors to this stigma may be due to the overlapping terminology, heterogeneous methodological approaches, and an almost dogmatic focus on different mechanistic underpinnings in different fields of research. Many clinicians and investigators explore the pathophysiological outcomes following long-term exposure to IH in an attempt to improve our understanding of sleep apnea (SA) and develop new treatment plans. However, others use IH as a tool to improve physiological outcomes such as blood pressure, motor function, and altitude acclimatization. Unfortunately, studies investigating the pathophysiology of SA or the potential benefit of IH use similar, unstandardized terminologies facilitating a confusion surrounding IH protocols and the intentions of various studies. In this perspective paper, we aim to highlight IH terminology-related issues with the aim of spurring harmonization of the terminology used in the field of IH research to account for distinct outcomes of hypoxia exposure depending on protocol and individuum.
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Affiliation(s)
- Gino S Panza
- Department of Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan, United States
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, Michigan, United States
| | - Johannes Burtscher
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Fei Zhao
- Department of Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan, United States
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, Michigan, United States
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Panza GS, Kissane DM, Puri S, Mateika JH. The hypoxic ventilatory response and hypoxic burden are predictors of the magnitude of ventilatory long-term facilitation in humans. J Physiol 2023; 601:4611-4623. [PMID: 37641466 PMCID: PMC11006398 DOI: 10.1113/jp285192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023] Open
Abstract
Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. The magnitude of these forms of plasticity might be influenced by anthropometric and physiological variables, as well as protocol elements. However, the impact of many of these variables on the magnitude of respiratory plasticity has not been established in humans. A meta-analysis was completed using anthropometric and physiological variables obtained from 124 participants that completed one of three intermittent hypoxia protocols. Simple correlations between the aggregate variables and the magnitude of PA and vLTF standardized to baseline was completed. Thereafter, the variables correlated to PA or vLTF were input into a multilinear regression equation. Baseline measures of the hypoxic ventilatory response was the sole predictor of PA (R = 0.370, P = 0.012). Similarly, this variable along with the hypoxic burden predicted the magnitude of vLTF (R = 0.546, P < 0.006 for both variables). In addition, the magnitude of PA was strongly correlated to vLTF (R = 0.617, P < 0.001). Anthropometric measures do not predict the magnitude of PA and vLTF in humans. Alternatively, the hypoxic ventilatory response was the sole predictor of PA, and in combination with the hypoxic burden, predicted the magnitude of vLTF. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity. KEY POINTS: Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. Many of the anthropometric and physiological variables that could impact the magnitude of these forms of plasticity are unknown. Anthropometric and physiological variables were measured from a total of 124 participants that completed one of three distinct intermittent hypoxia protocols. The variables correlated to PA or vLTF were input into a multilinear regression analysis. The hypoxic ventilatory response was the sole predictor of PA, while this variable in addition to the average hypoxic burden predicted the magnitude of vLTF. A strong correlation between PA and vLTF was also revealed. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity.
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Affiliation(s)
- Gino S Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI, USA
| | - Dylan M Kissane
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, USA
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Ostrowski D, Heesch CM, Kline DD, Hasser EM. Nucleus tractus solitarii is required for the development and maintenance of phrenic and sympathetic long-term facilitation after acute intermittent hypoxia. Front Physiol 2023; 14:1120341. [PMID: 36846346 PMCID: PMC9949380 DOI: 10.3389/fphys.2023.1120341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Exposure to acute intermittent hypoxia (AIH) induces prolonged increases (long term facilitation, LTF) in phrenic and sympathetic nerve activity (PhrNA, SNA) under basal conditions, and enhanced respiratory and sympathetic responses to hypoxia. The mechanisms and neurocircuitry involved are not fully defined. We tested the hypothesis that the nucleus tractus solitarii (nTS) is vital to augmentation of hypoxic responses and the initiation and maintenance of elevated phrenic (p) and splanchnic sympathetic (s) LTF following AIH. nTS neuronal activity was inhibited by nanoinjection of the GABAA receptor agonist muscimol before AIH exposure or after development of AIH-induced LTF. AIH but not sustained hypoxia induced pLTF and sLTF with maintained respiratory modulation of SSNA. nTS muscimol before AIH increased baseline SSNA with minor effects on PhrNA. nTS inhibition also markedly blunted hypoxic PhrNA and SSNA responses, and prevented altered sympathorespiratory coupling during hypoxia. Inhibiting nTS neuronal activity before AIH exposure also prevented the development of pLTF during AIH and the elevated SSNA after muscimol did not increase further during or following AIH exposure. Furthermore, nTS neuronal inhibition after the development of AIH-induced LTF substantially reversed but did not eliminate the facilitation of PhrNA. Together these findings demonstrate that mechanisms within the nTS are critical for initiation of pLTF during AIH. Moreover, ongoing nTS neuronal activity is required for full expression of sustained elevations in PhrNA following exposure to AIH although other regions likely also are important. Together, the data indicate that AIH-induced alterations within the nTS contribute to both the development and maintenance of pLTF.
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Affiliation(s)
- Daniela Ostrowski
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Biology, Truman State University, Kirksville, MO, United States
| | - Cheryl M. Heesch
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
| | - David D. Kline
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States
| | - Eileen M. Hasser
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States,*Correspondence: Eileen M. Hasser,
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8
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Debenham MIB, Grantham TDA, Smirl JD, Foster GE, Dalton BH. The effects of acute normobaric hypoxia on vestibular-evoked balance responses in humans. J Vestib Res 2023; 33:31-49. [PMID: 36530112 DOI: 10.3233/ves-220075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Hypoxia influences standing balance and vestibular function. OBJECTIVE The purpose here was to investigate the effect of hypoxia on the vestibular control of balance. METHODS Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces. RESULTS Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males. CONCLUSIONS Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway.
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Affiliation(s)
- M I B Debenham
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, The University of British Columbia, Kelowna, British Columbia, Canada
| | - T D A Grantham
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, The University of British Columbia, Kelowna, British Columbia, Canada
| | - J D Smirl
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - G E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, The University of British Columbia, Kelowna, British Columbia, Canada
| | - B H Dalton
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, The University of British Columbia, Kelowna, British Columbia, Canada
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9
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Vaughan S, Sankari A, Carroll S, Eshraghi M, Obiakor H, Yarandi H, Chowdhuri S, Salloum A, Badr MS. Tetraplegia is associated with increased hypoxic ventilatory response during nonrapid eye movement sleep. Physiol Rep 2022; 10:e15455. [PMID: 36065854 PMCID: PMC9446393 DOI: 10.14814/phy2.15455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 08/19/2022] [Accepted: 08/21/2022] [Indexed: 06/15/2023] Open
Abstract
People with cervical spinal cord injury (SCI) are likely to experience chronic intermittent hypoxia while sleeping. The physiological effects of intermittent hypoxia on the respiratory system during spontaneous sleep in individuals with chronic cervical SCI are unknown. We hypothesized that individuals with cervical SCI would demonstrate higher short- and long-term ventilatory responses to acute intermittent hypoxia (AIH) exposure than individuals with thoracic SCI during sleep. Twenty participants (10 with cervical SCI [9 male] and 10 with thoracic SCI [6 male]) underwent an AIH and sham protocol during sleep. During the AIH protocol, each participant experienced 15 episodes of isocapnic hypoxia using mixed gases of 100% nitrogen (N2 ) and 40% carbon dioxide (CO2 ) to achieve an oxygen saturation of less than 90%. This was followed by two breaths of 100% oxygen (O2 ). Measurements were collected before, during, and 40 min after the AIH protocol to obtain ventilatory data. During the sham protocol, participants breathed room air for the same amount of time that elapsed during the AIH protocol and at approximately the same time of night. Hypoxic ventilatory response (HVR) during the AIH protocol was significantly higher in participants with cervical SCI than those with thoracic SCI. There was no significant difference in minute ventilation (V.E. ), tidal volume (V.T. ), or respiratory frequency (f) during the recovery period after AIH in cervical SCI compared to thoracic SCI groups. Individuals with cervical SCI demonstrated a significant short-term increase in HVR compared to thoracic SCI. However, there was no evidence of ventilatory long-term facilitation following AIH in either group.
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Affiliation(s)
- Sarah Vaughan
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Abdulghani Sankari
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
- Department of Medical EducationAscension Providence HospitalSouthfieldMichiganUSA
| | - Sean Carroll
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Mehdi Eshraghi
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Harold Obiakor
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Hossein Yarandi
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Susmita Chowdhuri
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - Anan Salloum
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
| | - M. Safwan Badr
- Department of MedicineJohn D. Dingell VA Medical CenterDetroitMichiganUSA
- Department of Internal MedicineWayne State UniversityDetroitMichiganUSA
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10
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Camacho-Cardenosa A, Camacho-Cardenosa M, Tomas-Carus P, Timón R, Olcina G, Burtscher M. Acute physiological response to a normobaric hypoxic exposure: sex differences. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2022; 66:1495-1504. [PMID: 35585281 DOI: 10.1007/s00484-022-02298-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 04/26/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
Although preliminary studies suggested sex-related differences in physiological responses to altitude/hypoxia, controlled studies from standardised exposures to normobaric hypoxia are largely lacking. Hence, the goals of this study were to provide information on cardiorespiratory responses to a 7-h normobaric hypoxia exposure and to explore potential differences between men and women. In this crossover study, a total of 15 men and 14 women were subjected to a 7-h exposure in normoxia (FiO2: 21%) and normobaric hypoxia (FiO2: 15%). Values of peripheral oxygen saturation, heart rate, systolic and diastolic blood pressure and respiratory gases were recorded every hour (8 time points), and oxygen saturation every 30 min (15 time points). Compared to normoxia, exposure to hypoxia significantly increased minute ventilation from baseline to hour 7 in males (+ 71%) and females (+ 40%), significantly greater in men (p < 0.05). A steeper decrease in peripheral oxygen saturation until 2.5 h in hypoxia was seen in females compared to males (p < 0.05). In conclusion, the ventilatory response to hypoxia was more pronounced in men compared to women. Moreover, during the first hours in hypoxia, peripheral oxygen saturation dropped more markedly in women than in men, likely due an initially lower and/or less efficient ventilatory response to moderate hypoxia. Those findings should be considered when performing interventions for therapy or prevention in normobaric hypoxia. Nevertheless, further large-scaled and well-controlled studies are needed.
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Affiliation(s)
| | - Marta Camacho-Cardenosa
- Faculty of Sport Sciences, University of Extremadura, Cáceres, Spain.
- Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Av. Menéndez Pidal, Edificio IMIBIC, s/n, 14004, Córdoba, Córdoba, Spain.
| | - Pablo Tomas-Carus
- Departamento de Desporto e Saúde, Escola de Saúde e Desenvolvimento Humano, Universidade de Évora, Évora, Portugal
- Comprehensive Health Research Centre (CHRC), University of Évora, Évora, Portugal
| | - Rafael Timón
- Faculty of Sport Sciences, University of Extremadura, Cáceres, Spain
| | - Guillermo Olcina
- Faculty of Sport Sciences, University of Extremadura, Cáceres, Spain
| | - Martin Burtscher
- Sport Science, Medical Section, University of Innsbruck, Innsbruck, Austria
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11
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Panza GS, Puri S, Lin HS, Mateika JH. Divergent Ventilatory and Blood Pressure Responses are Evident Following Repeated Daily Exposure to Mild Intermittent Hypoxia in Males with OSA and Hypertension. Front Physiol 2022; 13:897978. [PMID: 35721527 PMCID: PMC9204590 DOI: 10.3389/fphys.2022.897978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/03/2022] [Indexed: 11/17/2022] Open
Abstract
Introduction: Resting minute ventilation and ventilation during and following hypoxia may be enhanced following daily exposure to mild intermittent hypoxia (MIH). In contrast, resting systolic blood pressure (SBP) is reduced following daily exposure to MIH. However, it is presently unknown if the reduction in resting SBP following daily exposure, is coupled with reduced SBP responses during and after acute exposure to MIH. Methods: Participants with obstructive sleep apnea (OSA) and hypertension (n = 10) were exposed to twelve 2-min bouts of MIH (oxygen saturation—87%)/day for 15 days. A control group (n = 6) was exposed to a sham protocol during which compressed air (i.e., FIO2 = 0.21) was inspired in place of MIH. Results: The hypoxic ventilatory response (HVR) and hypoxic systolic blood pressure response (HSBP) increased from the first to the last hypoxic episode on the initial (HVR: 0.08 ± 0.02 vs. 0.13 ± 0.02 L/min/mmHg, p = 0.03; HSBP: 0.13 ± 0.04 vs. 0.37 ± 0.06 mmHg/mmHg, p < 0.001) and final (HVR: 0.10 ± 0.01 vs. 0.15 ± 0.03 L/min/mmHg, p = 0.03; HSBP: 0.16 ± 0.03 vs. 0.41 ± 0.34 mmHg/mmHg, p < 0.001) day. The magnitude of the increase was not different between days (p ≥ 0.83). Following exposure to MIH, minute ventilation and SBP was elevated compared to baseline on the initial (MV: 16.70 ± 1.10 vs. 14.20 ± 0.28 L/min, p = 0.01; SBP: 167.26 ± 4.43 vs. 151.13 ± 4.56 mmHg, p < 0.001) and final (MV: 17.90 ± 1.25 vs. 15.40 ± 0.77 L/min, p = 0.01; SBP: 156.24 ± 3.42 vs. 137.18 ± 4.17 mmHg, p < 0.001) day. The magnitude of the increases was similar on both days (MV: 3.68 ± 1.69 vs. 3.22 ± 1.27 L/min, SBP: 14.83 ± 2.64 vs. 14.28 ± 1.66 mmHg, p ≥ 0.414). Despite these similarities, blood pressure at baseline and at other time points during the MIH protocol was reduced on the final compared to the initial day (p ≤ 0.005). Conclusion: The ventilatory and blood pressure responses during and following acute MIH were similar on the initial and final day of exposure. Alternatively, blood pressure was down regulated, while ventilation was similar at all time points (i.e., baseline, during and following MIH) after daily exposure to MIH.
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Affiliation(s)
- Gino S Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, United States.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States
| | - Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, United States.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States
| | - Ho-Sheng Lin
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, United States.,Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI, United States
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, United States.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI, United States.,Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, United States
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12
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Behrendt T, Bielitzki R, Behrens M, Glazachev OS, Schega L. Effects of Intermittent Hypoxia-Hyperoxia Exposure Prior to Aerobic Cycling Exercise on Physical and Cognitive Performance in Geriatric Patients—A Randomized Controlled Trial. Front Physiol 2022; 13:899096. [PMID: 35694402 PMCID: PMC9178199 DOI: 10.3389/fphys.2022.899096] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/09/2022] [Indexed: 01/04/2023] Open
Abstract
Background: It was recently shown that intermittent hypoxic-hyperoxic exposure (IHHE) applied prior to a multimodal training program promoted additional improvements in cognitive and physical performance in geriatric patients compared to physical training only. However, there is a gap in the literature to which extent the addition of IHHE can enhance the effects of an aerobic training. Therefore, the aim of this study was to investigate the efficacy of IHHE applied prior to aerobic cycling exercise on cognitive and physical performance in geriatric patients. Methods: In a randomized, two-armed, controlled, and single-blinded trial, 25 geriatric patients (77–94 years) were assigned to two groups: intervention group (IG) and sham control group (CG). Both groups completed 6 weeks of aerobic training using a motorized cycle ergometer, three times a week for 20 min per day. The IG was additionally exposed to intermittent hypoxic and hyperoxic periods for 30 min prior to exercise. The CG followed the similar procedure breathing sham hypoxia and hyperoxia (i.e., normoxia). Within 1 week before and after the interventions, cognitive performance was assessed with the Dementia-Detection Test (DemTect) and the Clock Drawing Test (CDT), while physical performance was measured using the Timed “Up and Go” Test (TUG) and the Short-Physical-Performance-Battery (SPPB). Results: No interaction effect was found with respect to the DemTect (ηp2 = 0.02). An interaction effect with medium effect size (ηp2 = 0.08) was found for CDT performance with a higher change over time for IG (d = 0.57) compared to CG (d = 0.05). The ANCOVA with baseline-adjustment indicated between-group differences with a large and medium effect size at post-test for the TUG (ηp2 = 0.29) and SPPB (ηp2 = 0.06) performance, respectively, in favour of the IG. Within-group post-hoc analysis showed that the TUG performance was worsened in the CG (d = 0.65) and remained unchanged in the IG (d = 0.19). Furthermore, SPPB performance was increased (d = 0.58) in IG, but no relevant change over time was found for CG (d = 0.00). Conclusion: The current study suggests that an additional IHHE prior to aerobic cycling exercise seems to be more effective to increase global cognitive functions as well as physical performance and to preserve functional mobility in geriatric patients in comparison to aerobic exercise alone after a 6-week intervention period.
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Affiliation(s)
- Tom Behrendt
- Department for Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
- *Correspondence: Tom Behrendt,
| | - Robert Bielitzki
- Department for Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Martin Behrens
- Department for Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
- Department of Orthopedics, Rostock University Medical Center, Rostock, Germany
| | - Oleg S. Glazachev
- Department Human Physiology, Institute of Clinical Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Lutz Schega
- Department for Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
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13
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Pollet A. A commentary on: Efficacy and time course of acute intermittent hypoxia effects in the upper extremities of people with cervical spinal cord injury. Exp Neurol 2022; 355:114123. [PMID: 35623393 DOI: 10.1016/j.expneurol.2022.114123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 05/18/2022] [Indexed: 11/17/2022]
Affiliation(s)
- Aviva Pollet
- Department of Health and Exercise Science, Colorado State University, Fort Collins, USA.
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14
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Panza GS, Puri S, Lin HS, Badr MS, Mateika JH. Daily Exposure to Mild Intermittent Hypoxia Reduces Blood Pressure in Male Patients with Obstructive Sleep Apnea and Hypertension. Am J Respir Crit Care Med 2022; 205:949-958. [PMID: 35015980 PMCID: PMC9838631 DOI: 10.1164/rccm.202108-1808oc] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Rationale: Daily exposure to mild intermittent hypoxia (MIH) may elicit beneficial cardiovascular outcomes. Objectives: To determine the effect of 15 days of MIH and in-home continuous positive airway pressure treatment on blood pressure in participants with obstructive sleep apnea and hypertension. Methods: We administered MIH during wakefulness 5 days/week for 3 weeks. The protocol consisted of twelve 2-minute bouts of hypoxia interspersed with 2 minutes of normoxia. End-tidal carbon dioxide was maintained 2 mm Hg above baseline values throughout the protocol. Control participants were exposed to a sham protocol (i.e., compressed air). All participants were treated with continuous positive airway pressure over the 3-week period. Results are mean ± SD. Measurements and Main Results: Sixteen male participants completed the study (experimental n = 10; control n = 6). Systolic blood pressure at rest during wakefulness over 24 hours was reduced after 15 days of MIH (142.9 ± 8.6 vs. 132.0 ± 10.7 mm Hg; P < 0.001), but not following the sham protocol (149.9 ± 8.6 vs. 149.7 ± 10.8 mm Hg; P = 0.915). Thus, the reduction in blood pressure from baseline was greater in the experimental group compared with control (-10.91 ± 4.1 vs. -0.17 ± 3.6 mm Hg; P = 0.003). Modifications in blood pressure were accompanied by increased parasympathetic and reduced sympathetic activity in the experimental group, as estimated by blood pressure and heart rate variability analysis. No detrimental neurocognitive and metabolic outcomes were evident following MIH. Conclusions: MIH elicits beneficial cardiovascular and autonomic outcomes in males with OSA and concurrent hypertension. Clinical trial registered with www.clinicaltrials.gov (NCT03736382).
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Affiliation(s)
- Gino S. Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and,Department of Physiology
| | - Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and,Department of Physiology
| | - Ho-Sheng Lin
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and,Department of Otolaryngology, and
| | - M. Safwan Badr
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and,Department of Physiology,,Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, Michigan
| | - Jason H. Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; and,Department of Physiology,,Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, Michigan
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15
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Welch JF, Nair J, Argento PJ, Mitchell GS, Fox EJ. Acute intermittent hypercapnic-hypoxia elicits central neural respiratory motor plasticity in humans. J Physiol 2022; 600:2515-2533. [PMID: 35348218 DOI: 10.1113/jp282822] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/25/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The occurrence of respiratory long-term facilitation following acute exposure to intermittent hypoxia is believed to be dependent upon CO2 regulation - mechanisms governing the critical role of CO2 have seldom been explored. We tested the hypothesis that acute intermittent hypercapnic-hypoxia (AIHH) enhances cortico-phrenic neurotransmission in awake healthy humans. The amplitude of diaphragmatic motor-evoked potentials induced by transcranial magnetic stimulation was increased after AIHH, but not the amplitude of compound muscle action potentials evoked by cervical magnetic stimulation. Mouth occlusion pressure (P0.1 , indicator of neural respiratory drive) was also increased after AIHH, but not tidal volume or minute ventilation. Thus, moderate AIHH elicits central neural mechanisms of respiratory motor plasticity, without measurable ventilatory long-term facilitation in awake humans. ABSTRACT Acute intermittent hypoxia (AIH) elicits long-term facilitation (LTF) of respiration. Although LTF is observed when CO2 is elevated during AIH in awake humans, the influence of CO2 on corticospinal respiratory motor plasticity is unknown. Thus, we tested the hypotheses that acute intermittent hypercapnic-hypoxia (AIHH): 1) enhances cortico-phrenic neurotransmission (reflecting volitional respiratory control); and 2) elicits ventilatory LTF (reflecting automatic respiratory control). Eighteen healthy adults completed four study visits. Day 1 consisted of anthropometry and pulmonary function testing. On Days 2, 3 and 4, in a balanced alternating sequence, participants received: AIHH, poikilocapnic AIH, and normocapnic-normoxia (Sham). Protocols consisted of 15, 60-s exposures with 90-s normoxic intervals. Transcranial (TMS) and cervical (CMS) magnetic stimulation were used to induce diaphragmatic motor-evoked potentials and compound muscle action potentials, respectively. Respiratory drive was assessed via mouth occlusion pressure (P0.1 ), and minute ventilation measured at rest. Dependent variables were assessed at baseline and 30-60 min post-exposures. Increases in TMS-evoked diaphragm potential amplitudes were observed following AIHH versus Sham (+28 ± 41%, p = 0.003), but not after AIH. No changes were observed in CMS-evoked diaphragm potential amplitudes. Mouth occlusion pressure also increased after AIHH (+21 ± 34%, p = 0.033), but not after AIH. Ventilatory LTF was not observed after any treatment. We demonstrate that AIHH elicits central neural mechanisms of respiratory motor plasticity and increases resting respiratory drive in awake humans. These findings may have important implications for neurorehabilitation after spinal cord injury and other neuromuscular disorders compromising respiratory motor function. Abstract Figure Legend In a single-blind, cross-over, sham-controlled trial, 18 healthy adults received in a balanced alternating sequence: normocapnic-normoxia (Sham), poikilocapnic acute intermittent hypoxia (AIH), and acute intermittent hypercapnic-hypoxia (AIHH). The study tested the hypothesis that AIHH enhances cortico-phrenic neurotransmission and elicits ventilatory long-term facilitation. Note the increase in the mean amplitude of diaphragmatic motor-evoked potentials (MEP) induced by transcranial magnetic stimulation 60 min after AIHH only, whereas the amplitude of diaphragmatic compound muscle action potentials evoked by cervical (phrenic nerve) stimulation were unchanged after AIHH, AIH and Sham. Traces are composite averages of all participants. Mouth occlusion pressure (P0.1 ), an indicator of resting respiratory drive, was increased after AIHH, but not after AIH or Sham (see yellow shaded area). Traces are mouth pressure at the onset of an occluded inspiration during resting breathing. Finally, tidal volume (VT ) was unchanged 30-60 min after AIHH, AIH and Sham. Our results indicate that moderate AIHH elicits a central neural mechanism of respiratory motor plasticity and increases resting respiratory drive in awake humans, without measurable ventilatory long-term facilitation. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Joseph F Welch
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy
| | - Jayakrishnan Nair
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy.,Department of Physical Therapy, Thomas Jefferson University, Philadelphia, PA, USA
| | - Patrick J Argento
- Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy
| | - Emily J Fox
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy.,Brooks Rehabilitation, Jacksonville, FL, USA
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16
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Vose AK, Welch JF, Nair J, Dale EA, Fox EJ, Muir GD, Trumbower RD, Mitchell GS. Therapeutic acute intermittent hypoxia: A translational roadmap for spinal cord injury and neuromuscular disease. Exp Neurol 2022; 347:113891. [PMID: 34637802 PMCID: PMC8820239 DOI: 10.1016/j.expneurol.2021.113891] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/29/2021] [Accepted: 10/03/2021] [Indexed: 01/03/2023]
Abstract
We review progress towards greater mechanistic understanding and clinical translation of a strategy to improve respiratory and non-respiratory motor function in people with neuromuscular disorders, therapeutic acute intermittent hypoxia (tAIH). In 2016 and 2020, workshops to create and update a "road map to clinical translation" were held to help guide future research and development of tAIH to restore movement in people living with chronic, incomplete spinal cord injuries. After briefly discussing the pioneering, non-targeted basic research inspiring this novel therapeutic approach, we then summarize workshop recommendations, emphasizing critical knowledge gaps, priorities for future research effort, and steps needed to accelerate progress as we evaluate the potential of tAIH for routine clinical use. Highlighted areas include: 1) greater mechanistic understanding, particularly in non-respiratory motor systems; 2) optimization of tAIH protocols to maximize benefits; 3) identification of combinatorial treatments that amplify plasticity or remove plasticity constraints, including task-specific training; 4) identification of biomarkers for individuals most/least likely to benefit from tAIH; 5) assessment of long-term tAIH safety; and 6) development of a simple, safe and effective device to administer tAIH in clinical and home settings. Finally, we update ongoing clinical trials and recent investigations of tAIH in SCI and other clinical disorders that compromise motor function, including ALS, multiple sclerosis, and stroke.
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Affiliation(s)
- Alicia K Vose
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Brooks Rehabilitation, Jacksonville, FL 32216, USA
| | - Joseph F Welch
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Brooks Rehabilitation, Jacksonville, FL 32216, USA
| | - Jayakrishnan Nair
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Erica A Dale
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32610, USA
| | - Emily J Fox
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Brooks Rehabilitation, Jacksonville, FL 32216, USA
| | - Gillian D Muir
- Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
| | - Randy D Trumbower
- Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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17
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Abstract
AbstractThe following review is designed to explore the pathophysiology of sleep apnea in aging women. The review initially introduces four endotypes (i.e., a more collapsible airway, upper airway muscle responsiveness, arousal threshold, and loop gain) that may have a role in the initiation of obstructive sleep apnea. Thereafter, sex differences in the prevalence of sleep apnea are considered along with differences in the prevalence that exist between younger and older women. Following this discussion, we consider how each endotype might contribute to the increase in prevalence of sleep apnea in aging women. Lastly, we address how modifications in one form of respiratory plasticity, long-term facilitation, that might serve to mitigate apneic events in younger women may be modified in aging women with obstructive sleep apnea. Overall, the published literature indicates that the prevalence of sleep apnea is increased in aging women. This increase is linked primarily to a more collapsible airway and possibly to reduced responsiveness of upper airway muscle activity. In contrast, modifications in loop gain or the arousal threshold do not appear to have a role in the increased prevalence of sleep apnea in aging women. Moreover, we suggest that mitigation of long-term facilitation could contribute to the increased prevalence of sleep apnea in aging women.
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18
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Barok R, Grittner JML, Dougherty BJ. The long-term impact of ovariectomy on ventilation and expression of phrenic long-term facilitation in female rats. Exp Physiol 2021; 106:2002-2012. [PMID: 34180081 PMCID: PMC8410681 DOI: 10.1113/ep089546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/18/2021] [Indexed: 01/04/2023]
Abstract
NEW FINDINGS What is the central question of this study? Would ovariectomy cause prolonged changes in ventilation and sustained loss of acute, intermittent hypoxia-induced neuroplasticity or would these outcomes be restored with time? What is the main finding and its importance? Our main findings demonstrate that ovariectomy elicits minimal alteration in overall breathing function but impairs acute, intermittent hypoxia-induced plasticity for ≤ 12 weeks. ABSTRACT Sex hormones are necessary to enable respiratory neuroplasticity, including phrenic long-term facilitation (pLTF), a form of respiratory motor plasticity elicited by acute, intermittent hypoxia (AIH). Female rats exhibit a progressive increase in phrenic nerve amplitude after AIH characteristic of pLTF only during pro-oestrus, the stage of the oestrous cycle notable for elevated circulating oestradiol levels. Removal of the ovaries [ovariectomy (OVX)], the primary source of circulating oestradiol, also eliminates AIH-induced pLTF after 1 week. Ovariectomy is used routinely as a model to examine the impact of sex hormones on CNS structure and function, but the long-term impact of OVX is rarely examined. Extra-ovarian sites of oestradiol synthesis, including multiple CNS sites, have been identified and might possess the capacity to restore oestradiol levels, in part, over time, impacting respiratory function and the expression of respiratory neuroplasticity. We examined both ventilation in awake, freely behaving female rats, using barometric plethysmography, and the expression of AIH-induced pLTF in anaesthetized, ventilated female rats 2 and 12 weeks after OVX and compared them with age-matched ovarian-intact female rats. Our findings indicate that chronic OVX had little impact on baseline breathing or in the response to respiratory challenge (10% O2 , 5% CO2 , balance N2 ) during plethysmography. However, OVX rats at both 2 and 12 weeks demonstrated a persistent loss of AIH-induced pLTF relative to control animals (P < 0.01), suggesting that other sources of oestradiol synthesis were insufficient to restore pLTF. These data are consistent with our previous work indicating that oestradiol plays a key role in expression of AIH-induced respiratory neuroplasticity.
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Affiliation(s)
- Rebecca Barok
- Rehabilitation Science Graduate Program, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Jessica M L Grittner
- Rehabilitation Science Graduate Program, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Brendan J Dougherty
- Divisions of Physical Therapy and Rehabilitation Science, Department of Rehabilitation Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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19
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Zhang Z, Sowho M, Otvos T, Sperandio LS, East J, Sgambati F, Schwartz A, Schneider H. A comparison of automated and manual sleep staging and respiratory event recognition in a portable sleep diagnostic device with in-lab sleep study. J Clin Sleep Med 2021; 16:563-573. [PMID: 32022670 PMCID: PMC7161441 DOI: 10.5664/jcsm.8278] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
STUDY OBJECTIVES The objectives were to develop and validate an algorithm for editing WatchPAT scoring and assess the accuracy in an unselected clinical population as well as age and sex substrata. METHODS Two hundred sixty-two participants were enrolled to undergo WatchPAT simultaneously with in-lab polysomnography (PSG) recordings for developing (n = 30), optimizing (n = 62), and validating (n = 170) an algorithm to review and edit respiratory events and sleep architecture of WatchPAT recordings, which was based on visual inspection of WatchPAT signals. Apnea-hypopnea index (AHI) and sleep indices were compared with PSG-derived and automated WatchPAT indices. RESULTS Although estimation of total sleep time (TST) was comparable between automated and manual algorithm, estimation of rapid eye movement (REM) sleep time was markedly improved with manual editing from 0.48, 23.0 min (-43.9 to 89.8) to 0.64, 18.3 min (-32.6 to 69.1) (correlation with PSG, mean difference [reference range] from PSG, respectively). Manual scoring also improved correlation and agreement with PSG AHI from 0.65, 2.5 events/h (-24.0 to 28.9) to 0.81, -4.5 events/h (-22.5 to 13.6) as well as concordance for categorical agreement of sleep-disordered breathing severity and concordance for detecting severe REM-related sleep-disordered breathing. Interscorer reliabilities were excellent for TST and AHI, while good for REM sleep time. The automated algorithm performed better in younger than in older patients, while performed similarly between men and women with respect to concordance statistics. The manual algorithm markedly improved concordances more in older patients and women than in their counterparts. CONCLUSIONS Our manual editing algorithm improves correlation and agreement with PSG-derived sleep and breathing indices. Sex and age influence the accuracy of automated analysis and the performance of manual editing on AHI concordance.
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Affiliation(s)
- Zhigang Zhang
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland.,Department of Geriatrics, Peking University First Hospital, Beijing, China
| | - Mudiaga Sowho
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Tamas Otvos
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Larissa Sanglard Sperandio
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Joshua East
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Frank Sgambati
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Alan Schwartz
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Hartmut Schneider
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
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20
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Chen Y, Chen Y, Wen F, He Z, Niu W, Ren C, Li N, Wang Q, Ren Y, Liang C. Does continuous positive airway pressure therapy benefit patients with coronary artery disease and obstructive sleep apnea? A systematic review and meta-analysis. Clin Cardiol 2021; 44:1041-1049. [PMID: 34145595 PMCID: PMC8364731 DOI: 10.1002/clc.23669] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/30/2021] [Accepted: 06/03/2021] [Indexed: 12/04/2022] Open
Abstract
The prevalent co‐morbidity of coronary artery disease (CAD) and obstructive sleep apnea (OSA) has attracted great interest. However, effects of continuous positive airway pressure (CPAP) in patients with OSA and CAD for cardiovascular outcomes and deaths are still controversial. Usage of CPAP among patients with CAD and OSA could decrease the risk of cardiovascular events and death in adults. PubMed, EMBASE, Web of science, and Cochrane Library were systematically searched. Studies that described association of CPAP treatment with cardiovascular events in CAD and OSA patients were included. The main outcome was the major adverse cardiovascular events (MACE), including all‐cause death, cardiovascular death, myocardial infarction (MI), stroke, and repeat revascularization. Summary relative risks (risk ratios [RRs]) and 95% confidence intervals (CIs) of outcomes were pooled and heterogeneity was assessed with the I2 statistic. Nine studies enrolling 2590 participants with OSA and CAD were included and extracted data. There was significant association of CPAP with reduced risk of MACE (RR, 0.73, 95% CI [0.55, 0.96]), particularly among those with AHI less than 30 events/h (RR, 0.43, 95% CI [0.22, 0.84]). Similarly, the same result was found in all‐cause death (RR, 0.66, 95% CI, [0.46, 0.94]) and cardiovascular death (RR, 0.495, 95% CI [0.292, 0.838]). Our data suggested that CPAP usage, compared to usual care, was associated with reduced risks of cardiovascular outcomes or death in patients with OSA and CAD, particularly in the subgroup with AHI less than 30 events/h, which still needs further studies to confirm.
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Affiliation(s)
- Yasha Chen
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Yihong Chen
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Feng Wen
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Zhiqing He
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Wenhao Niu
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Changzhen Ren
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Na Li
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Qinqin Wang
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Yusheng Ren
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Chun Liang
- Department of Cardiology, Shanghai Changzheng Hospital, Navy Medical University, Shanghai, China
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21
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Yamashiro SM, Kato T, Matsumoto T. Altered chemosensitivity to CO 2 during exercise. Physiol Rep 2021; 9:e14882. [PMID: 34110716 PMCID: PMC8191175 DOI: 10.14814/phy2.14882] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 11/24/2022] Open
Abstract
The effect of exercise on chemosensitivity to carbon dioxide (CO2 ) has been controversial. Most studies have been based on rebreathing to alter inspired CO2 which is poorly tolerated in exercise. Instead, inhaling a fixed 3% CO2 from rest to moderate exercise was found to be well tolerated by seven normal subjects enabling CO2 chemosensitivity to be studied with minimal negative reaction. Results showed that chemosensitivity to CO2 following 5-6 min of stimulation was significantly enhanced during mild exercise (p < 0.01). This motivated exploring how much of the dynamic ventilatory response to mild exercise breathing air could be predicted by a model with central and peripheral chemosensitivity. Chemoreceptor stimulation combined with hypercapnia has been associated with long-term facilitation of ventilation (LTF). 3% CO2 inhalation during moderate exercise led to ventilation augmentation consistent with LTF following 6 min of exercise in seven normal human subjects (p < 0.01). Increased ventilation could not be attributed to hypercapnia or metabolic changes. Moderate exercise breathing air resulted in significantly less augmentation. In conclusion, both peripheral and central chemosensitivity to CO2 increased in exercise with the peripheral chemoreceptors playing a dominant role. This separation of central and peripheral contributions was not previously reported. This chemoreceptor stimulation can lead to augmented ventilation consistent with LTF.
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Affiliation(s)
- Stanley M. Yamashiro
- Biomedical Engineering DepartmentUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Takahide Kato
- Department of General EducationNational Institute of TechnologyToyota CollegeToyotaJapan
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22
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Welch JF, Perim RR, Argento PJ, Sutor TW, Vose AK, Nair J, Mitchell GS, Fox EJ. Effect of acute intermittent hypoxia on cortico-diaphragmatic conduction in healthy humans. Exp Neurol 2021; 339:113651. [PMID: 33607080 PMCID: PMC8678369 DOI: 10.1016/j.expneurol.2021.113651] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 01/06/2023]
Abstract
Acute intermittent hypoxia (AIH) is a strategy to improve motor output in humans with neuromotor impairment. A single AIH session increases the amplitude of motor evoked potentials (MEP) in a finger muscle (first dorsal interosseous), demonstrating enhanced corticospinal neurotransmission. Since AIH elicits phrenic/diaphragm long-term facilitation (LTF) in rodent models, we tested the hypothesis that AIH augments diaphragm MEPs in humans. Eleven healthy adults (7 males, age = 29 ± 6 years) were tested. Transcranial and cervical magnetic stimulation were used to induce diaphragm MEPs and compound muscle action potentials (CMAP) recorded by surface EMG, respectively. Stimulus-response curves were generated prior to and 30-60 min after AIH. Diaphragm LTF was assessed by measurement of integrated EMG burst amplitude and frequency during eupnoeic breathing before and after AIH. Following baseline measurements, AIH was delivered from an oxygen generator connected to a facemask under poikilocapnic conditions (15 one minute episodes of 9% inspired oxygen with one minute room air intervals). There were no detectable changes in MEP (-1.5 ± 12.1%, p = 0.96) or CMAP (+0.1 ± 7.8%, p = 0.97) amplitudes across the stimulus-response curve. At stimulation intensities approximating 50% of the difference between minimum and maximum baseline amplitudes, MEP and CMAP amplitudes were also unchanged (p > 0.05). Further, no AIH effect was observed on diaphragm EMG activity during eupnoea post-AIH (p > 0.05). We conclude that unlike hand muscles, poikilocapnic AIH does not enhance diaphragm MEPs or produce diaphragm LTF in healthy humans.
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Affiliation(s)
- Joseph F Welch
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
| | - Raphael R Perim
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Patrick J Argento
- Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, USA
| | - Tommy W Sutor
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Alicia K Vose
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Jayakrishnan Nair
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Emily J Fox
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA; Brooks Rehabilitation, Jacksonville, FL, USA
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23
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Puri S, Panza G, Mateika JH. A comprehensive review of respiratory, autonomic and cardiovascular responses to intermittent hypoxia in humans. Exp Neurol 2021; 341:113709. [PMID: 33781731 PMCID: PMC8527806 DOI: 10.1016/j.expneurol.2021.113709] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/17/2021] [Accepted: 03/24/2021] [Indexed: 01/08/2023]
Abstract
This review explores forms of respiratory and autonomic plasticity, and associated outcome measures, that are initiated by exposure to intermittent hypoxia. The review focuses primarily on studies that have been completed in humans and primarily explores the impact of mild intermittent hypoxia on outcome measures. Studies that have explored two forms of respiratory plasticity, progressive augmentation of the hypoxic ventilatory response and long-term facilitation of ventilation and upper airway muscle activity, are initially reviewed. The role these forms of plasticity might have in sleep disordered breathing are also explored. Thereafter, the role of intermittent hypoxia in the initiation of autonomic plasticity is reviewed and the role this form of plasticity has in cardiovascular and hemodynamic responses during and following intermittent hypoxia is addressed. The role of these responses in individuals with sleep disordered breathing and spinal cord injury are subsequently addressed. Ultimately an integrated picture of the respiratory, autonomic and cardiovascular responses to intermittent hypoxia is presented. The goal of the integrated picture is to address the types of responses that one might expect in humans exposed to one-time and repeated daily exposure to mild intermittent hypoxia. This form of intermittent hypoxia is highlighted because of its potential therapeutic impact in promoting functional improvement and recovery in several physiological systems.
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Affiliation(s)
- Shipra Puri
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America
| | - Gino Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States of America; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States of America; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States of America.
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24
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Novel Influences of Sex and APOE Genotype on Spinal Plasticity and Recovery of Function after Spinal Cord Injury. eNeuro 2021; 8:ENEURO.0464-20.2021. [PMID: 33536234 PMCID: PMC7986541 DOI: 10.1523/eneuro.0464-20.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/30/2020] [Accepted: 01/22/2021] [Indexed: 12/16/2022] Open
Abstract
Spinal cord injuries can abolish both motor and sensory function throughout the body. Spontaneous recovery after injury is limited and can vary substantially between individuals. Despite an abundance of therapeutic approaches that have shown promise in preclinical models, there is currently a lack of effective treatment strategies that have been translated to restore function after spinal cord injury (SCI) in the human population. We hypothesized that sex and genetic background of injured individuals could impact how they respond to treatment strategies, presenting a barrier to translating therapies that are not tailored to the individual. One gene of particular interest is APOE, which has been extensively studied in the brain because of its allele-specific influences on synaptic plasticity, metabolism, inflammation, and neurodegeneration. Despite its prominence as a therapeutic target in brain injury and disease, little is known about how it influences neural plasticity and repair processes in the spinal cord. Using humanized mice, we examined how the ε3 and ε4 alleles of APOE influence the efficacy of therapeutic intermittent hypoxia (IH) in inducing spinally-mediated plasticity after cervical SCI (cSCI). IH is sufficient to enhance plasticity and restore motor function after experimental SCI in genetically similar rodent populations, but its effect in human subjects is more variable (Golder and Mitchell, 2005; Hayes et al., 2014). Our results demonstrate that both sex and APOE genotype determine the extent of respiratory motor plasticity that is elicited by IH, highlighting the importance of considering these clinically relevant variables when translating therapeutic approaches for the SCI community.
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25
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Si L, Zhang J, Wang Y, Cao J, Chen BY, Guo HJ. Obstructive sleep apnea and respiratory center regulation abnormality. Sleep Breath 2020; 25:563-570. [PMID: 32870421 DOI: 10.1007/s11325-020-02175-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 08/14/2020] [Accepted: 08/19/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE Obstructive sleep apnea (OSA) is a complex disease in which phenotypic analysis and understanding pathological mechanisms facilitate personalized treatment and outcomes. However, the pathophysiology responsible for this robust observation is incompletely understood. The objective of the present work was to review how respiratory center regulation varies during sleep and wakeness in patients with OSA. DATA SOURCES We searched for relevant articles up to December 31, 2019 in PubMed database. METHODS This review examines the current literature on the characteristics of respiratory center regulation during wakefulness and sleep in OSA, detection method, and phenotypic treatment for respiratory center regulation. RESULTS Mechanisms for ventilatory control system instability leading to OSA include different sleep stages in chemoresponsiveness to hypoxia and hypercapnia and different chemosensitivity at different time. One can potentially stabilize the breathing center in sleep-related breathing disorders by identifying one or more of these pathophysiological mechanisms. CONCLUSIONS Advancing mechanism research in OSA will guide symptom research and provide alternate and novel opportunities for effective treatment for patients with OSA.
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Affiliation(s)
- Liang Si
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jing Zhang
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Yan Wang
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jie Cao
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China.
| | - Bao-Yuan Chen
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China.
| | - Heng-Juan Guo
- Respiratory Department, Tianjin Medical University General Hospital, Tianjin, 300052, China
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26
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Vermeulen TD, Benbaruj J, Brown CV, Shafer BM, Floras JS, Foster GE. Peripheral chemoreflex contribution to ventilatory long-term facilitation induced by acute intermittent hypercapnic hypoxia in males and females. J Physiol 2020; 598:4713-4730. [PMID: 32744340 DOI: 10.1113/jp280458] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 07/30/2020] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS Ventilatory long-term facilitation (vLTF) refers to respiratory neuroplasticity that develops following intermittent hypoxia in both healthy and clinical populations. A sustained hypercapnic background is argued to be required for full vLTF expression in humans. We determined whether acute intermittent hypercapnic hypoxia elicits vLTF during isocapnic-normoxic recovery in healthy males and females. We further assessed whether tonic peripheral chemoreflex drive is necessary and contributes to the expression of vLTF. Following 40 min of intermittent hypercapnic hypoxia, minute ventilation was increased throughout 50 min of isocapnic-normoxic recovery. Inhibition of peripheral chemoreflex drive with hyperoxia attenuated the magnitude of vLTF. Males and females achieve vLTF through different respiratory recruitment patterns. ABSTRACT Ventilatory long-term facilitation (vLTF) refers to respiratory neuroplasticity that manifests as increased minute ventilation ( V ̇ I ) following intermittent hypoxia. In humans, hypercapnia sustained throughout intermittent hypoxia and recovery is considered necessary for vLTF expression. We examined whether acute intermittent hypercapnic hypoxia (IHH) induces vLTF, and if peripheral chemoreflex drive contributes to vLTF throughout isocapnic-normoxic recovery. In 19 individuals (9 females, age: 22 ± 3 years; mean ± SD), measurements of tidal volume (VT ), breathing frequency (fB ), V ̇ I , and end-tidal gases ( P ET O 2 and P ETC O 2 ), were made at baseline, during IHH and 50 min of recovery. Totalling 40 min, IHH included 1 min intervals of 40 s hypercapnic hypoxia (target P ET O 2 = 50 mmHg and P ETC O 2 = +4 mmHg above baseline) and 20 s normoxia. During baseline and recovery, dynamic end-tidal forcing maintained resting P ET O 2 and P ETC O 2 and delivered 1 min of hyperoxia ( P ET O 2 = 355 ± 7 mmHg) every 5 min. The depression in V ̇ I during hyperoxia was considered an index of peripheral chemoreflex drive. Throughout recovery V ̇ I was increased 4.6 ± 3.7 l min-1 from baseline (P < 0.01). Hyperoxia depressed V ̇ I at baseline, and augmented depression was evident following IHH (Δ V ̇ I = -0.8 ± 0.9 vs. -1.7 ± 1.3 l min-1 , respectively, P < 0.01). The vLTF was similar between sexes (P = 0.15), but males had larger increases in VT than females (sex-by-time interaction, P = 0.03), and females tended to increase fB (P = 0.09). During isocapnic-normoxic recovery following IHH: (1) vLTF is expressed in healthy humans; (2) vLTF expression is attenuated but not abolished with peripheral chemoreflex inhibition by hyperoxia, suggesting a contribution from central nervous pathways in vLTF expression; and (3) males and females develop similar vLTF through different ventilatory recruitment strategies.
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Affiliation(s)
- Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada.,Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Canada
| | - Jenna Benbaruj
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Courtney V Brown
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - John S Floras
- University Health Network and Mount Sinai Hospital Division of Cardiology, Department of Medicine, University of Toronto, Toronto, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
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27
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Puri S, El-Chami M, Shaheen D, Ivers B, Panza GS, Badr MS, Lin HS, Mateika JH. Variations in loop gain and arousal threshold during NREM sleep are affected by time of day over a 24-hour period in participants with obstructive sleep apnea. J Appl Physiol (1985) 2020; 129:800-809. [PMID: 32790595 DOI: 10.1152/japplphysiol.00376.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether time of day affects loop gain (LG) and the arousal threshold (AT) during non-rapid eye movement (NREM) sleep. Eleven men with obstructive sleep apnea (apnea-hypopnea index > 5 events/h) completed a constant-routine protocol that comprised 3-h sleep sessions in the evening [10 PM (1) to 1 AM], morning (6 AM to 9 AM), afternoon (2 PM to 5 PM), and subsequent evening [10 PM (2) to 1 AM]. During each sleep session LG and the AT were measured during NREM sleep with a model-based approach. Our results showed the presence of a rhythmicity in both LG (P < 0.0001) and the AT (P < 0.001) over a 24-h period. In addition, LG and the AT were greater in the morning compared with both evening sessions [6 AM vs. 10 PM (1) vs. 10 PM (2): LG (1 cycle/min): 0.71 ± 0.23 vs. 0.60 ± 0.22 (P = 0.01) vs. 0.56 ± 0.10 (P < 0.001), AT (fraction of eupneic breathing): 1.45 ± 0.47 vs. 1.28 ± 0.36 (P = 0.02) vs. 1.20 ± 0.18 (P = 0.001)]. No difference in LG and the AT existed between the evening sessions (LG: P = 0.27; AT: P = 0.24). LG was correlated to measures of the hypocapnic ventilatory response (i.e., a measure of chemoreflex sensitivity) (r = 0.72 and P = 0.045) and the critical closing pressure (i.e., a measure of airway collapsibility) (r = 0.77 and P = 0.02) that we previously published. We conclude that time of day, independent of hallmarks of sleep apnea, affects LG and the AT during NREM sleep. These modifications may contribute to increases in breathing instability in the morning compared with other periods throughout the day/night cycle in individuals with obstructive sleep apnea. In addition, efficaciousness of treatments for obstructive sleep apnea that target LG and the AT may be modified by a rhythmicity in these variables.NEW & NOTEWORTHY Loop gain and the arousal threshold during non-rapid eye movement (NREM) sleep are greater in the morning compared with the afternoon and evening. Loop gain measures are correlated to chemoreflex sensitivity and the critical closing pressure measured during NREM sleep in the evening, morning, and afternoon. Breathing (in)stability and efficaciousness of treatments for obstructive sleep apnea may be modulated by a circadian rhythmicity in loop gain and the arousal threshold.
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Affiliation(s)
- Shipra Puri
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Mohamad El-Chami
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - David Shaheen
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Blake Ivers
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Gino S Panza
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - M Safwan Badr
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan.,Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan.,Department of Biomedical Engineering, Wayne State University, Detroit, Michigan
| | - Ho-Sheng Lin
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan.,Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine and Karmanos Cancer Institute, Detroit, Michigan
| | - Jason H Mateika
- John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan.,Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan
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28
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Naidu A, Peters DM, Tan AQ, Barth S, Crane A, Link A, Balakrishnan S, Hayes HB, Slocum C, Zafonte RD, Trumbower RD. Daily acute intermittent hypoxia to improve walking function in persons with subacute spinal cord injury: a randomized clinical trial study protocol. BMC Neurol 2020; 20:273. [PMID: 32641012 PMCID: PMC7341658 DOI: 10.1186/s12883-020-01851-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/01/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Restoring community walking remains a highly valued goal for persons recovering from traumatic incomplete spinal cord injury (SCI). Recently, studies report that brief episodes of low-oxygen breathing (acute intermittent hypoxia, AIH) may serve as an effective plasticity-inducing primer that enhances the effects of walking therapy in persons with chronic (> 1 year) SCI. More persistent walking recovery may occur following repetitive (weeks) AIH treatment involving persons with more acute SCI, but this possibility remains unknown. Here we present our clinical trial protocol, designed to examine the distinct influences of repetitive AIH, with and without walking practice, on walking recovery in persons with sub-acute SCI (< 12 months) SCI. Our overarching hypothesis is that daily exposure (10 sessions, 2 weeks) to AIH will enhance walking recovery in ambulatory and non-ambulatory persons with subacute (< 12 months) SCI, presumably by harnessing endogenous mechanisms of plasticity that occur soon after injury. METHODS To test our hypothesis, we are conducting a randomized, placebo-controlled clinical trial on 85 study participants who we stratify into two groups according to walking ability; those unable to walk (non-ambulatory group) and those able to walk (ambulatory group). The non-ambulatory group receives either daily AIH (15, 90s episodes at 10.0% O2 with 60s intervals at 20.9% O2) or daily SHAM (15, 90s episodes at 20.9% O2 with 60s intervals at 20.9% O2) intervention. The ambulatory group receives either 60-min walking practice (WALK), daily AIH + WALK, or daily SHAM+WALK intervention. Our primary outcome measures assess overground walking speed (10-Meter Walk Test), endurance (6-Minute Walk Test), and balance (Timed Up & Go Test). For safety, we also measure levels of pain, spasticity, systemic hypertension, and autonomic dysreflexia. We record outcome measures at baseline, days 5 and 10, and follow-ups at 1 week, 1 month, 6 months, and 12 months post-treatment. DISCUSSION The goal of this clinical trial is to reveal the extent to which daily AIH, alone or in combination with task-specific walking practice, safely promotes persistent recovery of walking in persons with traumatic, subacute SCI. Outcomes from this study may provide new insight into ways to enhance walking recovery in persons with SCI. TRIAL REGISTRATION ClinicalTrials.gov, NCT02632422 . Registered 16 December 2015.
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Affiliation(s)
- Avantika Naidu
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, 1575 Cambridge Street, Boston, MA, 02138, USA
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Denise M Peters
- Department of Rehabilitation & Movement Science, University of Vermont, Burlington, VT, USA
| | - Andrew Q Tan
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, 1575 Cambridge Street, Boston, MA, 02138, USA
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Stella Barth
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Andrea Crane
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Angela Link
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Swapna Balakrishnan
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Heather B Hayes
- Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, USA
| | - Chloe Slocum
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, 1575 Cambridge Street, Boston, MA, 02138, USA
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Ross D Zafonte
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, 1575 Cambridge Street, Boston, MA, 02138, USA
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA
| | - Randy D Trumbower
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, 1575 Cambridge Street, Boston, MA, 02138, USA.
- Spaulding Research Institute, Spaulding Rehabilitation Hospital, Charlestown, MA, USA.
- Program in Neuroscience, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA, USA.
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29
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Association between obstructive sleep apnoea syndrome and the risk of cardiovascular diseases: an updated systematic review and dose–response meta-analysis. Sleep Med 2020; 71:39-46. [DOI: 10.1016/j.sleep.2020.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/08/2020] [Accepted: 03/10/2020] [Indexed: 01/11/2023]
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30
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Shimoura CG, Andrade MA, Toney GM. Central AT1 receptor signaling by circulating angiotensin II is permissive to acute intermittent hypoxia-induced sympathetic neuroplasticity. J Appl Physiol (1985) 2020; 128:1329-1337. [PMID: 32240022 DOI: 10.1152/japplphysiol.00094.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Acute intermittent hypoxia (AIH) triggers sympathetic long-term facilitation (sLTF), a progressive increase in sympathetic nerve activity (SNA) linked to central AT1 receptor (AT1R) activation by circulating angiotensin II (ANG II). Here, we investigated AIH activation of the peripheral renin-angiotensin system (RAS) and the extent to which the magnitude of RAS activation predicts the magnitude of AIH-induced sLTF. In anesthetized male Sprague-Dawley rats, plasma renin activity (PRA) increased in a linear fashion in response to 5 (P = 0.0342) and 10 (P < 0.0001) cycles of AIH, with PRA remaining at the 10th cycle level 1 h later, a period over which SNA progressively increased. On average, SNA ramping began at the AIH cycle 4.6 ± 0.9 (n = 12) and was similar in magnitude 1 h later whether AIH consisted of 5 or 10 cycles (n = 6/group). Necessity of central AT1R in post-AIH sLTF was affirmed by intracerebroventricular (icv) losartan (40 nmol, 2 µL; n = 5), which strongly attenuated both splanchnic (P = 0.0469) and renal (P = 0.0018) sLTF compared with vehicle [artificial cerebrospinal fluid (aCSF), 2 µL; n = 5]. Bilateral nephrectomy largely prevented sLTF, affirming the necessity of peripheral RAS activation. Sufficiency of central ANG II signaling was assessed in nephrectomized rats. Whereas ICV ANG II (0.5 ng/0.5 µL, 30 min) in nephrectomized rats exposed to sham AIH (n = 4) failed to cause SNA ramping, it rescued sLTF in nephrectomized rats exposed to five cycles of AIH [splanchnic SNA (SSNA), P = 0.0227; renal SNA (RSNA), P = 0.0390; n = 5]. Findings indicate that AIH causes progressive peripheral RAS activation, which stimulates an apparent threshold level of central AT1R signaling that plays a permissive role in triggering sLTF.NEW & NOTEWORTHY Acute intermittent hypoxia (AIH) triggers sympathetic long-term facilitation (sLTF) that relies on peripheral renin-angiotensin system (RAS) activation. Here, increasing AIH cycles from 5 to 10 proportionally increased RAS activity, but not the magnitude of post-AIH sLTF. Brain angiotensin II (ANG II) receptor blockade and nephrectomy each largely prevented sLTF, whereas central ANG II rescued it following nephrectomy. Peripheral RAS activation by AIH induces time-dependent neuroplasticity at an apparent central ANG II signaling threshold, triggering a stereotyped sLTF response.
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Affiliation(s)
- Caroline G Shimoura
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Mary Ann Andrade
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Glenn M Toney
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas.,Center for Biomedical Neuroscience, University of Texas Health San Antonio, San Antonio, Texas
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Starling-Smith TM, La Monica MB, Stout JR, Fukuda DH. Minimal Effects of Moderate Normobaric Hypoxia on the Upper Body Work-Time Relationship in Recreationally Active Women. High Alt Med Biol 2020; 21:62-69. [PMID: 31928420 DOI: 10.1089/ham.2019.0061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background: Sex-based differences in metabolism and morphological characteristics may result in unique exercise responses during periods of limited oxygen availability. Purpose: To evaluate the effects of moderate normobaric hypoxia on the parameters of the work-time relationship during upper body exercise in women. Materials and Methods: Thirteen recreationally active women (age: 22.7 ± 2.6 years; height: 167 ± 8.6 cm; weight: 66.4 ± 9.7 kg; body fat: 27.6% ± 5% body fat) completed a maximal graded exercise test in both normobaric hypoxia (H; fraction of inspired oxygen (FiO2) = 0.14) and normoxia (N; FiO2 = 0.20) on an arm ergometer to determine peak oxygen uptake (VO2peak) and peak power output (PPO). Each participant completed four constant, work rate, arm-cranking time-to-exhaustion tests at 90%-120% PPO in both environmental conditions. Linear regression was used to estimate critical power (CP) and anaerobic capacity (W') through the work-time relationship during the constant work rate tests. Paired sample t-tests compared mean differences between VO2peak, PPO, CP, and W' between conditions (normoxia vs. hypoxia). Two-way (condition × intensity) repeated measures analysis of variance (ANOVA) was used to compare total work (TW) and time to exhaustion. Results: Hypoxia significantly reduced VO2peak (N: 1.73 ± 0.31 L·minute-1 vs. H: 1.62 ± 0.27 L·minute-1, p = 0.008), but had no effects on PPO (N: 78.08 ± 14.51 W vs. H: 75.38 ± 13.46 W, p = 0.09), CP (N: 57.44 ± 18.89 W vs. H: 56.01 ± 12.36 W, p = 0.55), and W' (N: 4.81 ± 1.01 kJ vs. H: 4.56 ± 0.91 kJ, p = 0.51). No significant condition × intensity interactions were noted for TW or time to exhaustion (p > 0.05). Conclusions: Moderate normobaric hypoxia significantly reduced VO2peak, but had minimal effects on CP and W' using the work-time model in women.
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Affiliation(s)
| | | | - Jeffrey R Stout
- Department of Kinesiology, University of Central Florida, Orlando, Florida
| | - David H Fukuda
- Department of Kinesiology, University of Central Florida, Orlando, Florida
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Mashaqi S, Gozal D. The impact of obstructive sleep apnea and PAP therapy on all-cause and cardiovascular mortality based on age and gender - a literature review. Respir Investig 2019; 58:7-20. [PMID: 31631059 DOI: 10.1016/j.resinv.2019.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/28/2019] [Accepted: 08/20/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) is a common sleep disorder which negatively impacts different body systems, especially the cardiovascular system. The correlation between sleep related breathing disorders and cardiovascular diseases has been well studied. However, the impact of OSA on cardiovascular related mortality and the role of positive airway pressure therapy in decreasing mortality is unclear. We reviewed studies investigating the impact of OSA on all-cause and cardiovascular related mortality in both genders, and in different age groups. METHODS A literature search (PubMed) using two phrases "obstructive sleep apnea and co-morbidities in males and females" and "obstructive sleep apnea and co-morbidities by age" yielded a total of 214 articles. Nineteen articles met the inclusion criteria. RESULTS The studies reviewed showed conflicting results. Some showed that OSA increases all cause and cardiovascular related mortality predominantly in the middle-aged group (40-65) followed by a plateau or a reduction in mortality. Other studies showed a positive linear correlation between OSA and mortality up to the age of 80. The same controversy was noted for gender; some studies did not observe an increase in mortality in females with OSA, while others observed a trend for an increase in mortality in females. CONCLUSION There is a debate in the literature regarding the impact of OSA on all-cause and cardiovascular mortality in both genders and in different age groups. However, the variation in results might be related to different study designs and significant epidemiological prevalence of OSA in males and females.
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Affiliation(s)
- Saif Mashaqi
- Department of Sleep Medicine, University of North Dakota School of Medicine and Health Sciences, Fargo, ND, USA.
| | - David Gozal
- Department of Child Health and the Child Health Research Institute, University of Missouri School of Medicine, Columbia, MO, USA
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Griffin HS, Al Humoud S, Benson JG, Cooper BG, Coomaraswamy K, Balanos GM. An acute exposure to intermittent negative airway pressure elicits respiratory long-term facilitation in awake humans. Respir Physiol Neurobiol 2019; 267:20-26. [PMID: 31176890 DOI: 10.1016/j.resp.2019.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/30/2019] [Accepted: 05/29/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND A sustained elevation in respiratory drive following removal of the inducing stimulus is known as respiratory long-term facilitation (rLTF). We investigated whether an acute exposure to intermittent negative airway pressure (INAP) elicits rLTF in humans. METHOD 13 healthy males (20.9 ± 2.8 years) undertook two trials (INAP and Control). In the INAP trial participants were exposed to one hour of 30-second episodes of breathing against negative pressure (-10 cmH2O) interspersed by 60-second intervals of breathing at atmospheric pressure. In the Control trial participants breathed at atmospheric pressure for one hour. Ventilation following INAP (recovery phase) was compared to that during baseline. RESULTS Ventilation increased from baseline to recovery in the INAP trial (14.9 ± 0.9 vs 19.1 ± 0.7 L/min, P = 0.002). This increase was significantly greater than the equivalent during the Control trial (P = 0.019). Data shown as mean ± SEM. CONCLUSION In this study INAP elicited rLTF in awake, healthy humans. Further research is required to investigate the responsible mechanisms.
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Affiliation(s)
- Harry S Griffin
- Lung Function & Sleep, Queen Elizabeth Hospital Birmingham, B15 2GW, United Kingdom
| | - Shoug Al Humoud
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, B152TT, United Kingdom
| | - Joshua G Benson
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, B152TT, United Kingdom
| | - Brendan G Cooper
- Lung Function & Sleep, Queen Elizabeth Hospital Birmingham, B15 2GW, United Kingdom
| | | | - George M Balanos
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, B152TT, United Kingdom.
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McIntosh D, Dougherty BJ. Development of ventilatory long-term facilitation is dependent on estrous cycle stage in adult female rats. Respir Physiol Neurobiol 2019; 264:1-7. [PMID: 30898577 DOI: 10.1016/j.resp.2019.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 11/16/2022]
Abstract
Ventilatory long-term facilitation (vLTF) is a form of respiratory plasticity characterized by a progressive and sustained increase in minute ventilation over time following acute, intermittent hypoxia (AIH). Though vLTF has been repeatedly demonstrated in adult males (rats and humans), few studies have assessed vLTF in adult females and no studies have explored differential expression of vLTF across the normal female estrous cycle. We recently reported that AIH-induced plasticity of phrenic motor output (phrenic long-term facilitation, pLTF), a phenotypically similar form of respiratory plasticity presenting as a sustained increase in phrenic nerve amplitude, develops in adult female rats only during the proestrus stage of the estrous cycle, notable for high levels of serum estrogen. Here, we tested the hypothesis that AIH-induced vLTF would also be estrous-stage dependent; developing in female rats during proestrus, but not estrus. Barometric plethysmography in adult (4-5 months), normally cycling female rats revealed a progressive increase in minute ventilation for 60 min following AIH (5 × 5 min episodes; 10% O2) during proestrus indicative of vLTF, while estrus rats showed no changes in minute ventilation over the same time period. The development of vLTF in proestrus rats was driven by changes in tidal volume production versus respiratory frequency consistent with prior studies. These data are the first to investigate differential vLTF expression across the estrous cycle in adult female rats and highlight the importance of female estrous cycle stage as a critical physiological variable to consider in studies of AIH-induced plasticity.
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Affiliation(s)
- Danielle McIntosh
- University of Minnesota Medical School, Department of Rehabilitation Medicine, Divisions of Physical Therapy and Rehabilitation Science, 420 Delaware Street S.E. (MMC 388), Minneapolis, MN 55455, United States
| | - Brendan J Dougherty
- University of Minnesota Medical School, Department of Rehabilitation Medicine, Divisions of Physical Therapy and Rehabilitation Science, 420 Delaware Street S.E. (MMC 388), Minneapolis, MN 55455, United States.
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Panza GS, Alex RM, Yokhana SS, Lee Pioszak DS, Badr MS, Mateika JH. Increased Oxidative Stress, Loop Gain And The Arousal Threshold Are Clinical Predictors Of Increased Apnea Severity Following Exposure To Intermittent Hypoxia. Nat Sci Sleep 2019; 11:265-279. [PMID: 31695534 PMCID: PMC6817348 DOI: 10.2147/nss.s228100] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/04/2019] [Indexed: 01/06/2023] Open
Abstract
PURPOSE We determined if oxidative stress prior to sleep onset is correlated to loop gain (LG) and the arousal threshold (AT) during non-rapid eye movement (NREM) sleep. We also explored if LG and AT are correlated with apnea severity and indices of upper airway collapsibility during NREM sleep. METHODS Thirteen male participants with obstructive sleep apnea (apnea-hypopnea index > 5 events/hr) were administered an antioxidant or placebo cocktail while exposed to mild intermittent hypoxia in the awake state. Thereafter, loop gain and measures of arousal, apnea severity and upper airway collapsibility were ascertained during NREM sleep. RESULTS Modification in oxidative stress (i.e., 8-hydroxy-2-deoxyguanosine) prior to sleep onset was correlated to LG (r = 0.8, P = 0.003), the number (r = 0.71, P = 0.01) and duration (r = 0.63, P = 0.04) of apneic events and the percentage of time breathing was stable (r = -0.66, P = 0.03) during sleep. Using a forward stepwise regression analysis, our results showed that LG, AT, the ventilatory response to arousal and nadir end-tidal carbon dioxide were determinants of the apnea-hypopnea index (P value range = 0.04-0.001). In addition, the AT was a predictor of measures of upper airway collapsibility, including the hypopnea/apnea + hypopnea ratio and the degree of flow reduction that accompanied hypopneic events (P < 0.001). CONCLUSION Modifications in oxidative stress following exposure to intermittent hypoxia during wakefulness are positively associated with loop gain and apnea severity during NREM sleep. Moreover, an increase in the arousal threshold is a predictor of increased upper airway collapsibility.
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Affiliation(s)
- Gino S Panza
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Raichel M Alex
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Sanar S Yokhana
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Dorothy S Lee Pioszak
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - M Safwan Badr
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.,Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jason H Mateika
- Research and Development, John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.,Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Keller‐Ross ML, Sarkinen AL, Chantigian DP, Cross TJ, Johnson BD, Olson TP. Interaction of hypoxia and vascular occlusion on cardiorespiratory responses during exercise. TRANSLATIONAL SPORTS MEDICINE 2018. [DOI: 10.1002/tsm2.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Manda L. Keller‐Ross
- Division of Physical Therapy, Medical School University of Minnesota Minneapolis Minnesota
| | | | - Daniel P. Chantigian
- Division of Physical Therapy, Medical School University of Minnesota Minneapolis Minnesota
| | - Troy J. Cross
- Internal Medicine Mayo Clinic College of Medicine Rochester Minnesota
- Menzies Health Institute Queensland, Gold Coast Griffith University QLD Australia
| | - Bruce D. Johnson
- Internal Medicine Mayo Clinic College of Medicine Rochester Minnesota
| | - Thomas P. Olson
- Internal Medicine Mayo Clinic College of Medicine Rochester Minnesota
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Deacon-Diaz NL, Sands SA, McEvoy RD, Catcheside PG. Daytime loop gain is elevated in obstructive sleep apnea but not reduced by CPAP treatment. J Appl Physiol (1985) 2018; 125:1490-1497. [PMID: 30161007 DOI: 10.1152/japplphysiol.00175.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Reduced ventilatory control stability (elevated loop gain) is a key nonanatomical, pathological trait contributing to obstructive sleep apnea (OSA), yet the mechanisms responsible remain unclear. We sought to identify the key factors contributing to elevated loop gain in OSA (controller vs. plant contributions) and to examine whether abnormalities in these factors persist after OSA treatment. In 15 males (8 OSA, 7 height, weight- and age -matched controls), we measured loop gain, controller gain, and plant gain using a pseudorandom binary CO2 stimulation method during wakefulness. Factors potentially influencing plant gain were also assessed (supine lung volume via helium dilution and spirometry). Measures were repeated 2 and 6 wk after initiating continuous positive airway pressure treatment. Loop gain (LG) was higher in OSA versus controls (LG at 1 cycle/min 0.28 ± 0.04 vs. 0.16 ± 0.04, P = 0.046, respectively), and the controller exhibited a greater peak response to CO2 and faster roll-off in OSA. OSA patients also exhibited reduced forced expiratory volume in the first second and forced vital capacity compared with controls (92.2 ± 1.7 vs. 102.9 ± 3.5% predicted, P = 0.021; 93.4 ± 3.1 vs. 106.6 ± 3.6% predicted, P = 0.015, respectively). There was no effect of treatment on any variable. These findings confirm loop gain is higher in untreated OSA patients than in matched controls; however, this was not affected by treatment. NEW & NOTEWORTHY Elevated loop gain contributes to obstructive sleep apnea (OSA) pathophysiology. However, whether loop gain is inherently elevated in OSA or induced by OSA itself, whether it is elevated due to increased chemoreflex sensitivity or obesity-dependent reduced lung volume, and whether it is treatment reversible, are all currently uncertain. This study found loop gain was elevated in OSA versus age-, sex-, height-, and weight-matched controls. However, this was not altered by 6-wk continuous positive airway pressure treatment.
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Affiliation(s)
- Naomi Louise Deacon-Diaz
- Discipline of Physiology, School of Medical Sciences, University of Adelaide , Adelaide, South Australia , Australia.,Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia
| | - Scott A Sands
- Division of Sleep Medicine, Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School , Boston, Massachusetts
| | - R Doug McEvoy
- Discipline of Physiology, School of Medical Sciences, University of Adelaide , Adelaide, South Australia , Australia.,Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia.,College of Medicine, Flinders University , Bedford Park, South Australia , Australia
| | - Peter G Catcheside
- Discipline of Physiology, School of Medical Sciences, University of Adelaide , Adelaide, South Australia , Australia.,Adelaide Institute for Sleep Health: A Flinders Centre of Research Excellence, Repatriation General Hospital, Daw Park, South Australia, Australia.,College of Medicine, Flinders University , Bedford Park, South Australia , Australia
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Kwon Y, Jacobs DR, Lutsey PL, Brumback L, Chirinos JA, Mariani S, Redline S, Duprez DA. "Sleep disordered breathing and ECG R-wave to radial artery pulse delay, The Multi-Ethnic Study of Atherosclerosis". Sleep Med 2018; 48:172-179. [PMID: 29960211 PMCID: PMC6051731 DOI: 10.1016/j.sleep.2018.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 03/14/2018] [Accepted: 05/08/2018] [Indexed: 11/30/2022]
Abstract
BACKGROUND Electrocardiography R-wave to radial artery pulse delay (RRD) represents pulse transit time inclusive of pre-ejection period (PEP) and arterial pulse propagation time. RRD is proposed to largely reflect arterial stiffness when PEP is accounted for (shorter RRD = higher arterial stiffness). Sleep disordered breathing (SDB) causes intermittent hypoxemia and sympathetic activation, which negatively influences vascular function. We aimed to examine the association of measures of SDB with RRD. METHODS Our sample consisted of participants in the Multi-Ethnic Study of Atherosclerosis without prevalent cardiovascular disease who underwent a daytime arterial elasticity exam, cardiac magnetic resonance imaging (MRI), and overnight polysomnography. SDB measures of interest included apnea hypopnea index (AHI) and oxygen desaturation index (ODI) (N = 1173). RRD was regressed on each measure of SDB separately, with adjustment for other cardiovascular risk factors as well as for correlates of the PEP, another component of RRD, by including cardiac MRI measures of contractility and preload. RESULTS In multivariate analysis, among measures of SDB, ODI, a marker of intermittent hypoxemia, was inversely associated with RRD (β = -60.2 msec per SD [15.5/hr], p = 0.04). No significant association was found with AHI. In gender stratified analyses, ODI and AHI were predictive of RRD in men only (β = -111.3 msec per SD [15.5/hr], p = 0.01 and β = -100.3 msec per SD [16.1/hr], p = 0.02 respectively). CONCLUSION Severity of SDB as measured by ODI was associated with RRD, a marker of arterial stiffness. Thus, association of RRD with measures of SDB appears to be gender-dependent.
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Affiliation(s)
- Younghoon Kwon
- Department of Medicine, University of Virginia, Charlottesville, VA, USA.
| | - David R. Jacobs
- Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA
| | - Pamela L. Lutsey
- Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA
| | - Lyndia Brumback
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | | | - Sara Mariani
- Departments of Medicine, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, MA, USA
| | - Susan Redline
- Departments of Medicine, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, MA, USA
| | - Daniel A. Duprez
- Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN, USA
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Stipica Safic I, Pecotic R, Pavlinac Dodig I, Dogas Z, Valic Z, Valic M. Phrenic long-term depression evoked by intermittent hypercapnia is modulated by serotonergic and adrenergic receptors in raphe nuclei. J Neurophysiol 2018; 120:321-329. [DOI: 10.1152/jn.00776.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intermittent hypercapnia evokes prolonged depression of phrenic nerve activity (phrenic long-term depression, pLTD). This study was undertaken to investigate the role of 5-HT and α2-adrenergic receptors in the initiation of pLTD. Adult male urethane-anesthetized, vagotomized, paralyzed, and mechanically ventilated Sprague-Dawley rats were exposed to a protocol of acute intermittent hypercapnia (AIHc; 5 episodes of 15% CO2in air, each episode lasting 3 min). The experimental group received microinjection of the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT), the broad-spectrum 5-HT antagonist methysergide, or the α2-adrenergic antagonist yohimbine, whereas the control group received microinjection of 0.9% saline into the caudal raphe region. Peak phrenic nerve activity (pPNA) and burst frequency ( f) were analyzed during baseline (T0), during 5 hypercapnic episodes (THc1–THc5), and at 15, 30, and 60 min after the end of the last hypercapnic episode. In the control group, pPNA decreased 60 min after the end of the last hypercapnic episode compared with baseline values, i.e., pLTD developed ( P = 0.023). In the 8-OH-DPAT group, pPNA significantly decreased at T15, T30, and T60 compared with baseline values, i.e., pLTD developed ( P = 0.01). In the methysergide and yohimbine groups, AIHc did not evoke significant changes of the pPNA at T15, T30, and T60 compared with baseline values. In conclusion, activation of 5-HT1Areceptors accentuated induction of pLTD, whereas blockade of α2-adrenergic receptors prevented development of pLTD following AIHc in anesthetized rats. These results suggest that chemical modulation of 5-HT and α2-adrenergic receptors in raphe nuclei affects hypercapnia-induced pLTD, offering important insights in understanding the mechanisms involved in development of respiratory plasticity.NEW & NOTEWORTHY Hypercapnia is a concomitant feature of many breathing disorders, including obstructive sleep apnea. In this study, acute intermittent hypercapnia evoked development of phrenic long-term depression (pLTD) 60 min after the last hypercapnic episode that was preserved if the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide was microinjected in the caudal raphe region before the hypercapnic stimulus. This study highlights that both 5-HT and adrenergic receptor activation is needed for induction of pLTD in urethane-anesthetized rats following intermittent hypercapnia exposure.
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Affiliation(s)
- Ivona Stipica Safic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Renata Pecotic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Ivana Pavlinac Dodig
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Zoran Dogas
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
| | - Zoran Valic
- Department of Physiology, University of Split School of Medicine, Split, Croatia
| | - Maja Valic
- Department of Neuroscience, University of Split School of Medicine, Split, Croatia
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Botek M, Krejčí J, McKune A. Sex Differences in Autonomic Cardiac Control and Oxygen Saturation Response to Short-Term Normobaric Hypoxia and Following Recovery: Effect of Aerobic Fitness. Front Endocrinol (Lausanne) 2018; 9:697. [PMID: 30532736 PMCID: PMC6265316 DOI: 10.3389/fendo.2018.00697] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/05/2018] [Indexed: 01/06/2023] Open
Abstract
Introduction: The main aims of this study were to investigate autonomic nervous system (ANS) and arterial oxygen saturation (SpO2) responses to simulated altitude in males and females, and to determine the association between maximal oxygen uptake (VO2max) and these responses. Materials and Methods: Heart rate variability (HRV) and SpO2 were monitored in a resting supine position during Preliminary (6 min normoxia), Hypoxia (10 min, fraction of inspired oxygen (FiO2) of 9.6%, simulated altitude ~6,200 m) and Recovery (6 min normoxia) phases in 28 males (age 23.7 ± 1.7 years, normoxic VO2max 59.0 ± 7.8 ml.kg-1.min-1, body mass index (BMI) 24.2 ± 2.1 kg.m-2) and 30 females (age 23.8 ± 1.8 years, VO2max 45.1 ± 8.7 ml.kg-1.min-1, BMI 21.8 ± 3.0 kg.m-2). Spectral analysis of HRV quantified the ANS activity by means of low frequency (LF, 0.05-0.15 Hz) and high frequency (HF, 0.15-0.50 Hz) power, transformed by natural logarithm (Ln). Time domain analysis incorporated the square root of the mean of the squares of the successive differences (rMSSD). Results: There were no significant differences in SpO2 level during hypoxia between the males (71.9 ± 7.5%) and females (70.8 ± 7.1%). Vagally-related HRV variables (Ln HF and Ln rMSSD) exhibited no significant differences between sexes across each phase. However, while the sexes demonstrated similar Ln LF/HF values during the Preliminary phase, the males (0.5 ± 1.3) had a relatively higher (p = 0.001) sympathetic activity compared to females (-0.6 ± 1.4) during the Hypoxia phase. Oxygen desaturation during resting hypoxia was significantly correlated with VO2max in males (r = -0.45, p = 0.017) but not in females (r = 0.01, p = 0.952) and difference between regression lines were significant (p = 0.024). Conclusions: Despite similar oxygen desaturation levels, males exhibited a relatively higher sympathetic responses to hypoxia exposure compared with females. In addition, the SpO2 response to resting hypoxia exposure was related to maximal aerobic capacity in males but not females.
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Affiliation(s)
- Michal Botek
- Department of Natural Sciences in Kinanthropology, Faculty of Physical Culture, Palacký University Olomouc, Olomouc, Czechia
| | - Jakub Krejčí
- Department of Natural Sciences in Kinanthropology, Faculty of Physical Culture, Palacký University Olomouc, Olomouc, Czechia
- *Correspondence: Jakub Krejčí
| | - Andrew McKune
- Discipline of Sport and Exercise Science, School of Rehabilitation and Exercise Sciences, Research Institute for Sport and Exercise Science, University of Canberra, Canberra, ACT, Australia
- Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
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Shao L, Heizhati M, Yao X, Wang Y, Abulikemu S, Zhang D, Zhou L, Hong J, Li N. Influences of obstructive sleep apnea on blood pressure variability might not be limited only nocturnally in middle-aged hypertensive males. Sleep Breath 2017; 22:377-384. [PMID: 29150775 DOI: 10.1007/s11325-017-1571-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/11/2017] [Accepted: 09/11/2017] [Indexed: 01/26/2023]
Abstract
PURPOSE In this cross-sectional study, we analyzed the potential association between sleep measures and blood pressure variability. METHODS Ninety-three middle-aged hypertensive males, who underwent polysomnography and 24-h ambulatory blood pressure monitoring, were enrolled. Blood pressure variability was assessed by blood pressure standard deviation. Obstructive sleep apnea (apnea hypopnea index ≥ 15) was diagnosed in 52 (55.91%) patients. Mean body mass index and age were 27.77 ± 3.11 kg/m2 and 44.05 ± 8.07 years, respectively. RESULTS Hypertensive males with obstructive sleep apnea showed significantly higher 24-h, diurnal, and nocturnal diastolic blood pressure variability, compared to those without obstructive sleep apnea. While total cohort was further divided into two groups using the median of oxygen desaturation index, another indicator for severity of OSA, significant differences were also observed in 24-h, diurnal, and nocturnal diastolic blood pressure variability between two groups with higher and lower oxygen desaturation index. While subjects were also divided into two groups via the mean of sleep stage 1, hypertensive males with sleep stage 1 ≥ 8.1% showed significantly higher diurnal diastolic blood pressure variability than those with sleep stage 1 < 8.1%. Apnea hypopnea index was independently associated with 24-h and nocturnal diastolic blood pressure variability; oxygen desaturation index of 3% with 24-h diastolic, diurnal, and nocturnal diastolic blood pressure; and sleep stage 1 was with 24-h and with diurnal diastolic blood pressure variability in all study subjects. CONCLUSION Effects of obstructive sleep apnea on blood pressure variability may not be limited nocturnally.
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Affiliation(s)
- Liang Shao
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Mulalibieke Heizhati
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Xiaoguang Yao
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Yingchun Wang
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Suofeiya Abulikemu
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Delian Zhang
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Ling Zhou
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Jing Hong
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China
| | - Nanfang Li
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region China, The Center of Diagnosis, Treatment and Research of Hypertension in Xinjiang China, No. 91 Tianchi Road, Tianshan District, Urumqi, Xinjiang, 830001, China.
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Mateika JH, Panza G, Alex R, El-Chami M. The impact of intermittent or sustained carbon dioxide on intermittent hypoxia initiated respiratory plasticity. What is the effect of these combined stimuli on apnea severity? Respir Physiol Neurobiol 2017; 256:58-66. [PMID: 29097171 DOI: 10.1016/j.resp.2017.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/13/2017] [Accepted: 10/21/2017] [Indexed: 11/28/2022]
Abstract
The following review explores the effect that intermittent or sustained hypercapnia coupled to intermittent hypoxia has on respiratory plasticity. The review explores published work which suggests that intermittent hypercapnia leads to long-term depression of respiration when administered in isolation and prevents the initiation of long-term facilitation when administered in combination with intermittent hypoxia. The review also explores the impact that sustained hypercapnia alone and in combination with intermittent hypoxia has on the magnitude of long-term facilitation. After exploring the outcomes linked to intermittent hypoxia/hypercapnia and intermittent hypoxia/sustained hypercapnia the translational relevance of the outcomes as it relates to breathing stability during sleep is addressed. The likelihood that naturally induced cycles of intermittent hypoxia, coupled to oscillations in carbon dioxide that range between hypocapnia and hypercapnia, do not initiate long-term facilitation is addressed. Moreover, the conditions under which intermittent hypoxia/sustained hypercapnia could serve to improve breathing stability and mitigate co-morbidities associated with sleep apnea are considered.
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Affiliation(s)
- Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI, 48201, United States.
| | - Gino Panza
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Raichel Alex
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
| | - Mohamad El-Chami
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI, 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, United States
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El-Chami M, Sudan S, Lin HS, Mateika JH. Exposure to intermittent hypoxia and sustained hypercapnia reduces therapeutic CPAP in participants with obstructive sleep apnea. J Appl Physiol (1985) 2017; 123:993-1002. [DOI: 10.1152/japplphysiol.00204.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/30/2017] [Accepted: 07/01/2017] [Indexed: 12/31/2022] Open
Abstract
Our purpose was to determine whether exposure to mild intermittent hypoxia leads to a reduction in the therapeutic continuous positive airway pressure required to eliminate breathing events. Ten male participants were treated with twelve 2-min episodes of hypoxia ([Formula: see text] ≈50 mmHg) separated by 2-min intervals of normoxia in the presence of [Formula: see text] that was sustained 3 mmHg above baseline. During recovery from the last episode, the positive airway pressure was reduced in a stepwise fashion until flow limitation was evident. The participants also completed a sham protocol under normocapnic conditions, which mimicked the time frame of the intermittent hypoxia protocol. After exposure to intermittent hypoxia, the therapeutic pressure was significantly reduced (i.e., 5 cmH2O) without evidence of flow limitation (103.4 ± 6.3% of baseline, P = 0.5) or increases in upper airway resistance (95.6 ± 15.0% of baseline, P = 0.6). In contrast, a similar decrease in pressure was accompanied by flow limitation (77.0 ± 1.8% of baseline, P = 0.001) and an increase in upper airway resistance (167.2 ± 17.5% of baseline, P = 0.01) after the sham protocol. Consistent with the initiation of long-term facilitation of upper airway muscle activity, exposure to intermittent hypoxia reduced the therapeutic pressure required to eliminate apneic events that could improve treatment compliance. This possibility, coupled with the potentially beneficial effects of intermittent hypoxia on comorbidities linked to sleep apnea, suggests that mild intermittent hypoxia may have a multipronged therapeutic effect on sleep apnea. NEW & NOTEWORTHY Our new finding is that exposure to mild intermittent hypoxia reduced the therapeutic pressure required to treat sleep apnea. These findings are consistent with previous results, which have shown that long-term facilitation of upper muscle activity can be initiated following exposure to intermittent hypoxia in humans.
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Affiliation(s)
- Mohamad El-Chami
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Sukhesh Sudan
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Ho-Sheng Lin
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine and Karmanos Cancer Institute, Detroit, Michigan
| | - Jason H. Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan; and
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Lozo T, Komnenov D, Badr MS, Mateika JH. Sex differences in sleep disordered breathing in adults. Respir Physiol Neurobiol 2016; 245:65-75. [PMID: 27836648 DOI: 10.1016/j.resp.2016.11.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 10/26/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023]
Abstract
The prevalence of sleep disordered breathing is greater in men compared to women. This disparity could be due to sex differences in the diagnosis and presentation of sleep apnea, and the pathophysiological mechanisms that instigate this disorder. Women tend to report more non-typical symptoms of sleep apnea compared to men, and the presentation of apneic events are more prevalent in rapid compared to non-rapid eye movement sleep. In addition, there is evidence of sex differences in upper airway structure and mechanics and in neural mechanisms that impact on the control of breathing. The purpose of this review is to summarize the literature that addresses sex differences in sleep-disordered breathing, and to discuss the influence that upper airway mechanics, chemoreflex properties, and sex hormones have in modulating breathing during sleep in men and women.
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Affiliation(s)
- Tijana Lozo
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - M Safwan Badr
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Biomedical Engineering, Wayne State University Detroit, MI 48201, United States
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States.
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Komnenov D, Solarewicz JZ, Afzal F, Nantwi KD, Kuhn DM, Mateika JH. Intermittent hypoxia promotes recovery of respiratory motor function in spinal cord-injured mice depleted of serotonin in the central nervous system. J Appl Physiol (1985) 2016; 121:545-57. [DOI: 10.1152/japplphysiol.00448.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/05/2016] [Indexed: 12/22/2022] Open
Abstract
We examined the effect of repeated daily exposure to intermittent hypoxia (IH) on the recovery of respiratory and limb motor function in mice genetically depleted of central nervous system serotonin. Electroencephalography, diaphragm activity, ventilation, core body temperature, and limb mobility were measured in spontaneously breathing wild-type (Tph2+/+) and tryptophan hydroxylase 2 knockout (Tph2−/−) mice. Following a C2 hemisection, the mice were exposed daily to IH (i.e., twelve 4-min episodes of 10% oxygen interspersed with 4-min normoxic periods followed by a 90-min end-recovery period) or normoxia (i.e., sham protocol, 21% oxygen) for 10 consecutive days. Diaphragm activity recovered to prehemisection levels in the Tph2+/+ and Tph2−/− mice following exposure to IH but not normoxia [Tph2+/+ 1.3 ± 0.2 (SE) vs. 0.3 ± 0.2; Tph2−/− 1.06 ± 0.1 vs. 0.3 ± 0.1, standardized to prehemisection values, P < 0.01]. Likewise, recovery of tidal volume and breathing frequency was evident, although breathing frequency values did not return to prehemisection levels within the time frame of the protocol. Partial recovery of limb motor function was also evident 2 wk after spinal cord hemisection. However, recovery was not dependent on IH or the presence of serotonin in the central nervous system. We conclude that IH promotes recovery of respiratory function but not basic motor tasks. Moreover, we conclude that spontaneous or treatment-induced recovery of respiratory and motor limb function is not dependent on serotonin in the central nervous system in a mouse model of spinal cord injury.
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Affiliation(s)
- Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Julia Z. Solarewicz
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Fareeza Afzal
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Kwaku D. Nantwi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan
| | - Donald M. Kuhn
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan; and
| | - Jason H. Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
- Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan
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Navarrete-Opazo A, Alcayaga J, Sepúlveda O, Rojas E, Astudillo C. Repetitive Intermittent Hypoxia and Locomotor Training Enhances Walking Function in Incomplete Spinal Cord Injury Subjects: A Randomized, Triple-Blind, Placebo-Controlled Clinical Trial. J Neurotrauma 2016; 34:1803-1812. [PMID: 27329506 DOI: 10.1089/neu.2016.4478] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Incomplete spinal cord injuries (iSCI) leave spared synaptic pathways below the level of injury. Intermittent hypoxia (IH) elicits plasticity in the spinal cord and strengthens spared synaptic pathways, expressed as respiratory and somatic functional recovery in experimental animals and humans with iSCI. This study is a randomized, triple-blind, two-arm parallel clinical trial performed in Santiago, Chile. We compared the effects of a 4-week protocol of IH combined with body weight-supported treadmill training (BWSTT), with continuous normoxia (Nx) and BWSTT on 10-meter walk test (10MWT), 6-minute walk test (6MWT), and timed up and go (TUG) test in American Spinal Injury Association C and D individuals with iSCI. Subjects received daily IH (cycling 9%/21% O2 every 1.5 min, 15 cycles/day) or continuous Nx (21% O2) combined with 45 min BWSTT for 5 consecutive days, followed by IH/Nx 3 × per week (3 × wIH/Nx) for 3 additional weeks. Subjects were assessed at day 5, weekly from weeks 2-4, and at a 2-week follow-up. Daily IH plus BWSTT enhanced walking speed, expressed as decreased 10MWT time at day 5 versus baseline (IH: -10.2 ± 3.0 vs. Nx: -1.7 ± 1.7 sec, p = 0.006), and walking endurance expressed as increased 6MWT distance at day 5 versus baseline (IH: 43.0 ± 10.7 vs. Nx: 6.1 ± 3.4 m, p = 0.012), but not TUG time. Further, 3 × wIH maintained the daily IH-induced walking speed, and enhanced the daily IH-induced walking endurance, which is maintained up to the 2-week follow-up. We conclude that daily IH enhances walking recovery in subjects with iSCI, confirming previous findings. Moreover, 3 × wIH prolonged or enhanced daily IH-induced walking speed and endurance improvements, respectively, up to 5 weeks post-daily IH. Repetitive IH may be a safe and effective therapeutic alternative for persons with iSCI.
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Affiliation(s)
| | - Julio Alcayaga
- 2 Biology Department, Universidad de Chile , Santiago, Chile
| | | | - Enrique Rojas
- 1 Teletón Rehabilitation Institute , Santiago, Chile
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Pamenter ME, Powell FL. Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis. Compr Physiol 2016; 6:1345-85. [PMID: 27347896 DOI: 10.1002/cphy.c150026] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. © 2016 American Physiological Society. Compr Physiol 6:1345-1385, 2016.
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Affiliation(s)
| | - Frank L Powell
- Physiology Division, Department of Medicine, University of California San Diego, La Jolla, California, USA
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48
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The Effects of Sex on Cardiopulmonary Responses to Acute Normobaric Hypoxia. High Alt Med Biol 2016; 17:108-15. [DOI: 10.1089/ham.2015.0114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Mateika JH, Komnenov D. Intermittent hypoxia initiated plasticity in humans: A multipronged therapeutic approach to treat sleep apnea and overlapping co-morbidities. Exp Neurol 2016; 287:113-129. [PMID: 27170208 DOI: 10.1016/j.expneurol.2016.05.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/18/2016] [Accepted: 05/03/2016] [Indexed: 10/21/2022]
Abstract
Over the past three decades exposure to intermittent hypoxia (IH) has generally been considered a stimulus associated with a number of detrimental outcomes. However, there is sufficient evidence to link IH to many beneficial outcomes but they have largely been ignored, particularly in the field of sleep medicine in the United States. Recent reviews have postulated that this apparent contradiction is related to the severity and duration of exposure to IH; mild forms of IH initiate beneficial outcomes while severe forms of IH are coupled to detrimental consequences. In the present review we explore the role that IH has in initiating respiratory plasticity and the potential this form of plasticity has to mitigate obstructive sleep apnea (OSA) in humans. In taking this approach, we address the possibility that IH could serve as an adjunct therapy coupled with continuous positive airway pressure (CPAP) to treat OSA. Our working hypothesis is that exposure to mild IH leads to respiratory plasticity that manifests in increased stability of the upper airway, which could ultimately reduce the CPAP required to treat OSA. In turn, this reduction could increase CPAP compliance and extend the length of treatment each night, which might improve the magnitude of outcome measures. Improved treatment compliance coupled with the direct effect that IH has on numerous overlapping conditions (i.e. asthma, chronic obstructive pulmonary disease, spinal cord injury) may well lead to substantial improvements that exceed outcomes following treatment with CPAP alone. Overall, this review will consider evidence from the published literature which suggests that IH could serve as an effective multipronged therapeutic approach to treat sleep apnea and its overlapping co-morbidities.
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Affiliation(s)
- Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States.
| | - Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
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Valic M, Pecotic R, Pavlinac Dodig I, Valic Z, Stipica I, Dogas Z. Intermittent hypercapnia-induced phrenic long-term depression is revealed after serotonin receptor blockade with methysergide in anaesthetized rats. Exp Physiol 2015; 101:319-31. [DOI: 10.1113/ep085161] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 11/20/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Maja Valic
- Department of Neuroscience; University of Split School of Medicine; Split Croatia
| | - Renata Pecotic
- Department of Neuroscience; University of Split School of Medicine; Split Croatia
| | - Ivana Pavlinac Dodig
- Department of Neuroscience; University of Split School of Medicine; Split Croatia
| | - Zoran Valic
- Department of Physiology; University of Split School of Medicine; Split Croatia
| | - Ivona Stipica
- Department of Neuroscience; University of Split School of Medicine; Split Croatia
| | - Zoran Dogas
- Department of Neuroscience; University of Split School of Medicine; Split Croatia
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