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DeConne TM, Fancher IS, Edwards DG, Trott DW, Martens CR. CD8 + T-cell metabolism is related to cerebrovascular reactivity in middle-aged adults. Am J Physiol Regul Integr Comp Physiol 2024; 326:R416-R426. [PMID: 38406845 DOI: 10.1152/ajpregu.00267.2023] [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: 11/30/2023] [Revised: 02/13/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
Cerebrovascular reactivity (CVR) decreases with advancing age, contributing to increased risk of cognitive impairment; however, the mechanisms underlying the age-related decrease in CVR are incompletely understood. Age-related changes to T cells, such as impaired mitochondrial respiration, increased inflammation, likely contribute to peripheral and cerebrovascular dysfunction in animals. However, whether T-cell mitochondrial respiration is related to cerebrovascular function in humans is not known. Therefore, we hypothesized that peripheral T-cell mitochondrial respiration would be positively associated with CVR and that T-cell glycolytic metabolism would be negatively associated with CVR. Twenty middle-aged adults (58 ± 5 yr) were recruited for this study. T cells were separated from peripheral blood mononuclear cells. Cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR, a marker of glycolytic activity) were measured using extracellular flux analysis. CVR was quantified using the breath-hold index (BHI), which reflects the change in blood velocity in the middle-cerebral artery (MCAv) during a 30-s breath-hold. In contrast to our hypothesis, we found that basal OCR in CD8+ T cells (β = -0.59, R2 = 0.27, P = 0.019) was negatively associated with BHI. However, in accordance with our hypothesis, we found that basal ECAR (β = -2.20, R2 = 0.29, P = 0.015) and maximum ECAR (β = -50, R2 = 0.24, P = 0.029) were negatively associated with BHI in CD8+ T cells. There were no associations observed in CD4+ T cells. These associations appeared to be primarily mediated by an association with the pressor response to the breath-hold test. Overall, our findings suggest that CD8+ T-cell respiration and glycolytic activity may influence CVR in humans.NEW & NOTEWORTHY Peripheral T-cell metabolism is related to in vivo cerebrovascular reactivity in humans. Higher glycolytic metabolism in CD8+ T cells was associated with lower cerebrovascular reactivity to a breath-hold in middle-aged adults, which is possibly reflective of a more proinflammatory state in midlife.
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Affiliation(s)
- Theodore M DeConne
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
| | - Ibra S Fancher
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
| | - David G Edwards
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
| | - Daniel W Trott
- Department of Kinesiology, University of Texas at Arlington, Arlington, Texas, United States
| | - Christopher R Martens
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, United States
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2
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Chapp AD, Shan Z, Chen QH. Acetic Acid: An Underestimated Metabolite in Ethanol-Induced Changes in Regulating Cardiovascular Function. Antioxidants (Basel) 2024; 13:139. [PMID: 38397737 PMCID: PMC10886048 DOI: 10.3390/antiox13020139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/13/2024] [Accepted: 01/18/2024] [Indexed: 02/25/2024] Open
Abstract
Acetic acid is a bioactive short-chain fatty acid produced in large quantities from ethanol metabolism. In this review, we describe how acetic acid/acetate generates oxidative stress, alters the function of pre-sympathetic neurons, and can potentially influence cardiovascular function in both humans and rodents after ethanol consumption. Our recent findings from in vivo and in vitro studies support the notion that administration of acetic acid/acetate generates oxidative stress and increases sympathetic outflow, leading to alterations in arterial blood pressure. Real-time investigation of how ethanol and acetic acid/acetate modulate neural control of cardiovascular function can be conducted by microinjecting compounds into autonomic control centers of the brain and measuring changes in peripheral sympathetic nerve activity and blood pressure in response to these compounds.
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Affiliation(s)
- Andrew D. Chapp
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhiying Shan
- Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI 49931, USA;
| | - Qing-Hui Chen
- Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI 49931, USA;
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3
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Bourdas DI, Geladas ND. Physiological responses during static apnoea efforts in elite and novice breath-hold divers before and after two weeks of dry apnoea training. Respir Physiol Neurobiol 2024; 319:104168. [PMID: 37797907 DOI: 10.1016/j.resp.2023.104168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/30/2023] [Accepted: 10/01/2023] [Indexed: 10/07/2023]
Abstract
This study examined the effect of breath-hold (BH) training on apnoeic performance in novice BH divers (NBH:n = 10) and compared them with data from elite BH divers (EBH:n = 11). Both groups performed 5-maximal BHs (PRE). The NBH group repeated this protocol after two weeks of BH training (POST). The NBH group during BH efforts significantly increased red blood cell concentration (4.56 ± 0.16Mio/μl) by 5.06%, hemoglobin oxygen saturation steady state duration (110.32 ± 29.84 s) by 15.48%, and breath-hold time (BHT:144.19 ± 47.35 s) by 33.77%, primarily due to a 59.70% increase in struggle phase (71.85 ± 30.89 s), in POST. EBH group exhibited longer BHT (283.95 ± 36.93 s) and struggle-phase (150.10 ± 34.69 s) than NBH (POST). Elite divers recorded a higher peak MAP (153.18 ± 12.28 mmHg) compared to novices (PRE:123.70 ± 15.65 mmHg, POST:128.30 ± 19.16 mmHg), suggesting that a higher peak MAP is associated with a better BHT. The concurrent abrupt increase of diaphragmatic activity and MAP, seen only in the EBH group, suggests a potential interaction. Additionally, apnoea training increases red blood cells concentration in repeated apnoea efforts and increases BH stamina.
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Affiliation(s)
- Dimitrios I Bourdas
- Section of Sport Medicine & Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, Ethnikis Antistasis 41, 17237 Daphni, Greece.
| | - Nickos D Geladas
- Section of Sport Medicine & Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, Ethnikis Antistasis 41, 17237 Daphni, Greece
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Santos JX, Silva PYF, Cruz MCLD, Silva BFVE, Azevedo IG, Pereira SA. Real-time changes in rib cage expansion and use of abdominal mechanical stimulation in newborns: a quasi-experimental study. REVISTA PAULISTA DE PEDIATRIA : ORGAO OFICIAL DA SOCIEDADE DE PEDIATRIA DE SAO PAULO 2023; 42:e2023032. [PMID: 38126599 PMCID: PMC10742371 DOI: 10.1590/1984-0462/2024/42/2023032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 09/10/2023] [Indexed: 12/23/2023]
Abstract
OBJECTIVE To assess the rib cage expansion and respiratory rate in newborns using an abdominal stabilization band. METHODS The study included 32 newborns of both genders, with gestational age between 35 and 41 weeks. The abdominal stabilization band was used for 15 minutes between the xiphoid process and the anterosuperior iliac crest, with an abdominal contention 0.5cm smaller than the abdominal circumference. The rib cage expansion was evaluated by a breathing transducer (Pneumotrace II™) three minutes before using the band, during the use (15 minutes), and ten minutes after removing the band. The Shapiro-Wilk test verified data normality, and the Wilcoxon test compared the variables considering rib cage expansion and respiratory rate. Significance was set to p<0.05. RESULTS There was an increase in respiratory rate when comparing before and ten minutes after removing (p=0.008) the abdominal stabilization band, as well as when comparing during its use and ten minutes after its removal (p=0.001). There was also an increase in rib cage expansion when comparing before and during the use of the abdominal stabilization band (p=0.005). CONCLUSIONS The use of the abdominal stabilization band promoted an increase in the rib cage expansion and respiratory rate in the assessed newborns and may be a viable option to improve the respiratory kinematics of this population.
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Wan HY, Bunsawat K, Amann M. Autonomic cardiovascular control during exercise. Am J Physiol Heart Circ Physiol 2023; 325:H675-H686. [PMID: 37505474 PMCID: PMC10659323 DOI: 10.1152/ajpheart.00303.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/11/2023] [Accepted: 07/23/2023] [Indexed: 07/29/2023]
Abstract
The cardiovascular response to exercise is largely determined by neurocirculatory control mechanisms that help to raise blood pressure and modulate vascular resistance which, in concert with regional vasodilatory mechanisms, promote blood flow to active muscle and organs. These neurocirculatory control mechanisms include a feedforward mechanism, known as central command, and three feedback mechanisms, namely, 1) the baroreflex, 2) the exercise pressor reflex, and 3) the arterial chemoreflex. The hemodynamic consequences of these control mechanisms result from their influence on the autonomic nervous system and subsequent alterations in cardiac output and vascular resistance. Although stimulation of the baroreflex inhibits sympathetic outflow and facilitates parasympathetic activity, central command, the exercise pressor reflex, and the arterial chemoreflex facilitate sympathetic activation and inhibit parasympathetic drive. Despite considerable understanding of the cardiovascular consequences of each of these mechanisms in isolation, the circulatory impact of their interaction, which occurs when various control systems are simultaneously activated (e.g., during exercise at altitude), has only recently been recognized. Although aging and cardiovascular disease (e.g., heart failure, hypertension) have both been recognized to alter the hemodynamic consequences of these regulatory systems, this review is limited to provide a brief overview on the action and interaction of neurocirculatory control mechanisms in health.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
| | - Kanokwan Bunsawat
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
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Shaw DM, Bloomfield PM, Benfell A, Hughes I, Gant N. Recovery from acute hypoxia: A systematic review of cognitive and physiological responses during the 'hypoxia hangover'. PLoS One 2023; 18:e0289716. [PMID: 37585402 PMCID: PMC10431643 DOI: 10.1371/journal.pone.0289716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/21/2023] [Indexed: 08/18/2023] Open
Abstract
Recovery of cognitive and physiological responses following a hypoxic exposure may not be considered in various operational and research settings. Understanding recovery profiles and influential factors can guide post-hypoxia restrictions to reduce the risk of further cognitive and physiological deterioration, and the potential for incidents and accidents. We systematically evaluated the available evidence on recovery of cognitive and basic physiological responses following an acute hypoxic exposure to improve understanding of the performance and safety implications, and to inform post-hypoxia restrictions. This systematic review summarises 30 studies that document the recovery of either a cognitive or physiological index from an acute hypoxic exposure. Titles and abstracts from PubMed (MEDLINE) and Scopus were searched from inception to July 2022, of which 22 full text articles were considered eligible. An additional 8 articles from other sources were identified and also considered eligible. The overall quality of evidence was moderate (average Rosendal score, 58%) and there was a large range of hypoxic exposures. Heart rate, peripheral blood haemoglobin-oxygen saturation and heart rate variability typically normalised within seconds-to-minutes following return to normoxia or hyperoxia. Whereas, cognitive performance, blood pressure, cerebral tissue oxygenation, ventilation and electroencephalogram indices could persist for minutes-to-hours following a hypoxic exposure, and one study suggested regional cerebral tissue oxygenation requires up to 24 hours to recover. Full recovery of most cognitive and physiological indices, however, appear much sooner and typically within ~2-4 hours. Based on these findings, there is evidence to support a 'hypoxia hangover' and a need to implement restrictions following acute hypoxic exposures. The severity and duration of these restrictions is unclear but should consider the population, subsequent requirement for safety-critical tasks and hypoxic exposure.
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Affiliation(s)
- David M. Shaw
- Aviation Medicine Unit, Royal New Zealand Air Force Base Auckland, Whenuapai, Auckland, New Zealand
| | - Peter M. Bloomfield
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
| | - Anthony Benfell
- Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Isadore Hughes
- Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Nicholas Gant
- Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
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Delliaux S, Ichinose M, Watanabe K, Fujii N, Nishiyasu T. Muscle metaboreflex activation during hypercapnia modifies nonlinear heart rhythm dynamics, increasing the complexity of the sinus node autonomic regulation in humans. Pflugers Arch 2023; 475:527-539. [PMID: 36645512 DOI: 10.1007/s00424-022-02780-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/01/2022] [Accepted: 12/04/2022] [Indexed: 01/17/2023]
Abstract
Muscle metaboreflex activation during hypercapnia leads to enhanced pressive effects that are poorly understood while autonomic responses including baroreflex function are not documented. Thus, we assessed heart rate variability (HRV) that is partly due to autonomic influences on sinus node with linear tools (spectral analysis of instantaneous heart period), baroreflex set point and sensitivity with the heart period-arterial pressure transfer function and sequences methods, and system coupling through the complexity of RR interval dynamics with nonlinear tools (Poincaré plots and approximate entropy (ApEn)). We studied ten healthy young men at rest and then during muscle metaboreflex activation (MMA, postexercise muscle ischemia) and hypercapnia (HCA, PetCO2 = + 10 mmHg from baseline) separately and combined (MMA + HCA). The strongest pressive responses were observed during MMA + HCA, while baroreflex sensitivity was similarly lowered in the three experimental conditions. HRV was significantly different in MMA + HCA compared to MMA and HCA separately, with the lowest total power spectrum (p < 0.05), including very low frequency (p < 0.05), low frequency (p < 0.05), and high frequency (tendency) power spectra decreases, and the lowest Poincaré plot short-term variability index (SD1): SD1 = 36.2 ms (MMA + HCA) vs. SD1 = 43.1 ms (MMA, p < 0.05) and SD1 = 46.1 ms (HCA, p < 0.05). Moreover, RR interval dynamic complexity was significantly increased only in the MMA + HCA condition (ApEn increased from 1.04 ± 0.04, 1.07 ± 0.02, and 1.05 ± 0.03 to 1.10 ± 0.03, 1.13 ± 0.04, and 1.17 ± 0.03 in MMA, HCA, and MMA + HCA conditions, respectively; p < 0.01). These results suggest that in healthy young men, muscle metaboreflex activation during hypercapnia leads to interactions that reduce parasympathetic influence on the sinus node activity but complexify its dynamics.
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Affiliation(s)
- Stephane Delliaux
- Aix Marseille Univ, INSERM, INRAE, C2VN, Marseille, France.
- Assistance Publique - Hôpitaux de Marseille, APHM, Hôpital Nord, Pôle Cardiovasculaire et Thoracique, Laboratoire de Physiologie Respiratoire - Explorations à l'Exercice, Marseille, France.
- Laboratory of Physiology - Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.
- Japan Society for the Promotion of Science, Tokyo, Japan.
| | - Masashi Ichinose
- Laboratory of Physiology - Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
- School of Business and Administration, Meiji University, Tokyo, Japan
| | - Kazuhito Watanabe
- Laboratory of Physiology - Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Naoto Fujii
- Laboratory of Physiology - Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Takeshi Nishiyasu
- Laboratory of Physiology - Circulation, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
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8
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Baby SM, Zaidi F, Hunsberger GE, Sokal D, Gupta I, Conde SV, Chew D, Rall K, Coatney RW. Acute effects of insulin and insulin-induced hypoglycaemia on carotid body chemoreceptor activity and cardiorespiratory responses in dogs. Exp Physiol 2023; 108:280-295. [PMID: 36459572 PMCID: PMC10103873 DOI: 10.1113/ep090584] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 11/07/2022] [Indexed: 12/03/2022]
Abstract
NEW FINDINGS What is the central question of this study? What are the effects of insulin and insulin-induced hypoglycaemia on carotid body chemoreceptor activity in vivo and how do carotid body chemoreceptor stimulation-mediated cardiorespiratory responses in beagle dogs compare during euglycaemia and insulin-induced hypoglycaemia? What is the main finding and its importance? Intracarotid insulin administration leads to sustained increase in carotid body chemoreceptor activity and respiratory response with significant cardiovascular effects. Insulin-induced hypoglycaemia exacerbated NaCN-mediated carotid body chemoreceptor activity and respiratory response with enhanced cardiovascular reflex response. These findings suggest that insulin-induced hypoglycaemia augments the carotid body chemoreceptors to initiate the adaptive counter-regulatory responses to restore the normoglycaemic condition. ABSTRACT The carotid body chemoreceptors (CBC) play an important role in the adaptive counter-regulatory response to hypoglycaemia by evoking the CBC-mediated sympathetic neuronal system to restore normoglycaemia. Ex vivo studies have shown varied responses of insulin-induced hypoglycaemia on CBC function, and several in vivo studies have indirectly established the role of CBCs in restoring normoglycaemia in both animals and humans. However, a direct effect of insulin and/or insulin-induced hypoglycaemia on CBC activity is not established in animal models. Therefore, the aim of this study was to evaluate in vivo effects of insulin and insulin-induced hypoglycaemia on CBC activity and cardiorespiration in a preclinical large animal model. The carotid sinus nerve (CSN) activity and cardiorespiratory responses to sodium cyanide (NaCN; 25 µg/kg) were compared before (euglycaemic) and after (hypoglycaemic) intracarotid administration of insulin (12.5-100 µU/dogs) in beagle dogs. Insulin administration increased CSN activity and minute ventilation (V ̇ $\dot V$ E ) with significant (P < 0.0001) effects on heart rate and blood pressure. Insulin-mediated effects on CSN and cardiorespiration were sustained and the change inV ̇ $\dot V$ E was driven by tidal volume only. Insulin significantly (P < 0.0001) lowered blood glucose level. NaCN-mediated CSN activity andV ̇ $\dot V$ E were significantly (P < 0.0001) augmented during insulin-induced hypoglycaemia. The augmentedV ̇ $\dot V$ E was primarily driven by respiratory frequency and partially by tidal volume. The cardiovascular reflex response mediated through CBC stimulation was significantly (P < 0.0001) exacerbated during insulin-induced hypoglycaemia. Collectively, these results demonstrate direct effects of insulin and insulin-induced hypoglycaemia on CBC chemosensitivity to potentiate CBC-mediated neuroregulatory pathways to initiate adaptive neuroendocrine and cardiorespiratory counter-regulatory responses to restore normoglycaemia.
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Affiliation(s)
- Santhosh M. Baby
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | - Faisal Zaidi
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | | | - David Sokal
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Isha Gupta
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Silvia V. Conde
- NOVA Medical SchoolFaculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
| | - Daniel Chew
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Kristen Rall
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | - Robert W. Coatney
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
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Shafer BM, Nardone M, Incognito AV, Vermeulen TD, Teixeira AL, Millar PJ, Sheel AW, West C, Ayas N, Foster GE. Acute hypoxia elicits lasting reductions in the sympathetic action potential transduction of arterial blood pressure in males. J Physiol 2023; 601:669-687. [PMID: 36542455 DOI: 10.1113/jp283979] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Post-hypoxia sympathoexcitation does not elicit corresponding changes in vascular tone, suggesting diminished sympathetic signalling. Blunted sympathetic transduction following acute hypoxia, however, has not been confirmed and the effects of hypoxia on the sympathetic transduction of mean arterial pressure (MAP) as a function of action potential (AP) activity is unknown. We hypothesized that MAP changes would be blunted during acute hypoxia but restored in recovery and asynchronous APs would elicit smaller MAP changes than synchronous APs. Seven healthy males (age: 24 (3) years; BMI: 25 (3) kg/m2 ) underwent 20 min isocapnic hypoxia (PET O2 : 47 (2) mmHg) and 30 min recovery. Multi-unit microneurography (muscle sympathetic nerve activity; MSNA) and continuous wavelet transform with matched mother wavelet was used to detect sympathetic APs during baseline, hypoxia, early (first 7 min) and late (last 7 min) recovery. AP groups were classified as synchronous APs, asynchronous APs (occurring outside an MSNA burst) and no AP activity. Sympathetic transduction of MAP was quantified using signal-averaging, with ΔMAP tracked following AP group cardiac cycles. Following synchronous APs, ΔMAP was reduced in hypoxia (+1.8 (0.9) mmHg) and early recovery (+1.5 (0.7) mmHg) compared with baseline (+3.1 (2.2) mmHg). AP group-by-condition interactions show that at rest asynchronous APs attenuate MAP reductions compared with no AP activity (-0.4 (1.1) vs. -2.2 (1.2) mmHg, respectively), with no difference between AP groups in hypoxia, early or late recovery. Sympathetic transduction of MAP is blunted in hypoxia and early recovery. At rest, asynchronous sympathetic APs contribute to neural regulation of MAP by attenuating nadir pressure responses. KEY POINTS: Acute isocapnic hypoxia elicits lasting sympathoexcitation that does not correspond to parallel changes in vascular tone, suggesting blunted sympathetic transduction. Signal-averaging techniques track the magnitude and temporal cardiovascular responses following integrated muscle sympathetic nerve activity (MSNA) burst and non-burst cardiac cycles. However, this does not fully characterize the effects of sympathetic action potential (AP) activity on blood pressure control. We show that hypoxia blunts the sympathetic transduction of mean arterial pressure (MAP) following synchronous APs that form integrated MSNA bursts and that sympathetic transduction of MAP remains attenuated into early recovery. At rest, asynchronous APs attenuate the reduction in MAP compared with cardiac cycles following no AP activity, thus asynchronous sympathetic APs appear to contribute to the neural regulation of blood pressure. The results advance our understanding of sympathetic transduction of arterial pressure during and following exposure to acute isocapnic hypoxia in humans.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Chris West
- Faculty of Medicine, University of British Columbia, Kelowna, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, Canada.,Centre for Chronic Disease Prevention and Management, University of British Columbia, Kelowna, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Najib Ayas
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, 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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10
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Bourdillon N, Aebi MR, Kayser B, Bron D, Millet GP. Both Hypoxia and Hypobaria Impair Baroreflex Sensitivity but through Different Mechanisms. Int J Sports Med 2022; 44:177-183. [PMID: 36455595 PMCID: PMC9977572 DOI: 10.1055/a-1960-3407] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Baroreflex sensitivity (BRS) is a measure of cardiovagal baroreflex and is lower in normobaric and hypobaric hypoxia compared to normobaric normoxia. The aim of this study was to assess the effects of hypobaria on BRS in normoxia and hypoxia. Continuous blood pressure and ventilation were recorded in eighteen seated participants in normobaric normoxia (NNx), hypobaric normoxia (HNx), normobaric hypoxia (NHx) and hypobaric hypoxia (HHx). Barometric pressure was matched between NNx vs. NHx (723±4 mmHg) and HNx vs. HHx (406±4 vs. 403±5 mmHg). Inspired oxygen pressure (PiO2) was matched between NNx vs. HNx (141.2±0.8 vs. 141.5±1.5 mmHg) and NHx vs. HHx (75.7±0.4 vs. 74.3±1.0 mmHg). BRS was assessed using the sequence method. BRS significantly decreased in HNx, NHx and HHx compared to NNx. Heart rate, mean systolic and diastolic blood pressures did not differ between conditions. There was the specific effect of hypobaria on BRS in normoxia (BRS was lower in HNx than in NNx). The hypoxic and hypobaric effects do not add to each other resulting in comparable BRS decreases in HNx, NHx and HHx. BRS decrease under low barometric pressure requires future studies independently controlling O2 and CO2 to identify central and peripheral chemoreceptors' roles.
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Affiliation(s)
- Nicolas Bourdillon
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland,Correspondence Dr. Nicolas
Bourdillon Institute of Sport
ScienceISSULUniversity of
Lausanne1015
LausanneSwitzerland+ 33603370729
| | - Mathias Rolland Aebi
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland,Wissenschaft & Technologie, armasuisse, Thun,
Switzerland
| | - Bengt Kayser
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland
| | - Denis Bron
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland
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11
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Wan HY, Weavil JC, Thurston TS, Georgescu VP, Morrissey CK, Amann M. On the hemodynamic consequence of the chemoreflex and muscle mechanoreflex interaction in women and men: two tales, one story. J Physiol 2022; 600:3671-3688. [PMID: 35710103 PMCID: PMC9378608 DOI: 10.1113/jp283051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/14/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cardiovascular response resulting from the activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), was previously shown to be different between women and men; this study focused on the hemodynamic consequence of the interaction of these two sympathoexcitatory reflexes. MMR and CR were activated by passive leg movement and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Individual and interactive reflex effects on central and peripheral hemodynamics were quantified in healthy young women and men. In men, the MMR:O2 -CR and MMR:CO2 -CR interactions restricted peripheral hemodynamics, likely by potentiating sympathetic vasoconstriction. In women, the MMR:O2 -CR interaction facilitated central and peripheral hemodynamics, likely by potentiating sympathetic vasodilation; however, the MMR:CO2 -CR interaction was simply additive for the central and peripheral hemodynamics. The interaction between the MMR and the CR exerts a profound influence on the autonomic control of cardiovascular function in humans, with the hemodynamic consequences differing between women and men. ABSTRACT The cardiovascular response resulting from the individual activation of the muscle mechanoreflex (MMR), or the chemoreflex (CR), is different between men and women. Whether the hemodynamic consequence resulting from the interaction of these sympathoexcitatory reflexes is also sex-dependent remains unknown. MMR and CR were activated by passive leg movement (LM) and exposure to hypoxia (O2 -CR), or hypercapnia (CO2 -CR), respectively. Twelve young men and 12 young women completed two experimental protocols: 1) resting in normoxia (PET O2 : ∼83mmHg, PET CO2 : ∼34mmHg), normocapnic hypoxia (PET O2 : ∼48mmHg, PET CO2 : ∼34mmHg), and hyperoxic hypercapnia (PET O2 : ∼524mmHg, PET CO2 : ∼44mmHg); 2) LM under the same gas conditions. During the MMR:O2 -CR coactivation, in men, the observed blood pressure (MAP) and cardiac output (CO) were not different (additive effect), while the observed leg blood flow (LBF) and vascular conductance (LVC) were significantly lower (hypo-additive), compared with the sum of the responses elicited by each reflex alone. In women, the observed MAP was not different (additive) while the observed CO, LBF, and LVC were significantly greater (hyper-additive), compared with the summated responses. During the MMR:CO2 -CR coactivation, in men, the observed MAP, CO, and LBF were not different (additive), while the observed LVC was significantly lower (hypo-additive), compared with the summated responses. In women, the observed MAP was significantly higher (hyper-additive), while the observed CO, LBF, and LVC were not different (additive), compared with the summated responses. The interaction of the MMR and CR has a pronounced influence on the autonomic cardiovascular control, with the hemodynamic consequences differing between men and women. Abstract figure legend The chemoreflex and the muscle mechanoreflex are sympathoexcitatory mechanisms which, via neural feedback to the cardiovascular centre in the medulla, mediate neurocirculatory responses during physical activity. The interaction of the peripheral chemoreflex and muscle mechanoreflex potentiates vasoconstriction in men, but potentiates vasodilatation in women (left panel). The interaction of the central chemoreflex and muscle mechanoreflex also potentiates vasoconstriction in men, whereas the reflex interaction is simply additive for the vasomotor tone in women (right panel). This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
| | | | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT.,Geriatric Research, Education, and Clinical Center, VAMC, Salt Lake City, UT.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
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12
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Shafer BM, Incognito AV, Vermeulen TD, Nardone M, Teixeira AL, Klassen SA, Millar PJ, Foster GE. Action potential amplitude and baroreflex resetting of action potential clusters mediate hypoxia-induced sympathetic long-term facilitation. J Physiol 2022; 600:3127-3147. [PMID: 35661360 DOI: 10.1113/jp282933] [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: 02/01/2022] [Accepted: 05/03/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Acute isocapnic hypoxia resets the arterial baroreflex and permits long-lasting sympathoexcitation called sympathetic long-term facilitation. Our understanding of sympathetic long-term facilitation following hypoxia in humans is based on multiunit muscle sympathetic nerve activity and does not fully characterize the underlying baroreflex control of sympathetic neuronal subpopulations or their discharge/recruitment strategies. We show that sympathetic long-term facilitation is mediated by baroreflex resetting of sympathetic action potential clusters to higher arterial pressure operating points, a reduction in the percentage of action potentials firing asynchronously, and a shift toward larger amplitude action potential activity. The results advance our fundamental understanding of how the sympathetic nervous system mediates sympathetic long-term facilitation following exposure to acute isocapnic hypoxia in humans. ABSTRACT Baroreflex resetting permits sympathetic long-term facilitation (sLTF) following hypoxia; however, baroreflex control of action potential (AP) clusters and AP recruitment patterns facilitating sLTF is unknown. We hypothesized that baroreflex resetting of arterial pressure operating points (OPs) of AP clusters and recruitment of large-amplitude APs would mediate sLTF following hypoxia. Eight men (age: 24 (3) yrs; BMI: 24 (3) kg/m2 ) underwent 20-min isocapnic hypoxia (PET O2 : 47 (2) mmHg) and 30-min recovery. Multi-unit microneurography (muscle sympathetic nerve activity; MSNA) and a continuous wavelet transform with matched mother wavelet was used to detect sympathetic APs during baseline, hypoxia, early (first 5-min), and late recovery (last 5-min). AP amplitude (normalized to largest baseline AP amplitude), percent APs occurring outside a MSNA burst (% asynchronous APs), and proportion of APs firing in small (1-3), medium (4-6), and large (7-10) normalized cluster sizes was calculated. Normalized clusters were used to assess baroreflex OPs and sensitivity. Hypoxia increased total MSNA activity, which remained elevated during recovery (P<0.0001). Baroreflex OPs were shifted rightward for all clusters in recovery, with no effect on slope. Compared to baseline, AP amplitude was elevated by 3 (2) % and 4 (2) % while asynchronous APs were reduced by 9 (5) % and 7 (6) % in early and late recovery, respectively. In early recovery, the proportion of APs firing in large clusters was increased compared to baseline. Hypoxia-induced sLTF is mediated by baroreflex resetting of AP clusters to higher OPs, reduced asynchronous AP firing, and increased contribution from large-amplitude APs. Abstract figure legend Eight healthy men underwent 20-min isocapnic hypoxia and 30-min recovery. The study tested the hypothesis that baroreflex resetting of arterial pressure operating points (OPs) of action potential (AP) clusters and recruitment of large-amplitude APs would mediate sympathetic long-term facilitation (sLTF) following acute hypoxic exposure. Hypoxia increased multi-unit muscle sympathetic nerve activity (MSNA; measured via microneurography), which remained elevated throughout recovery. Sympathetic APs were detected in the filtered MSNA neurogram using a continuous wavelet transform with matched mother wavelet. An effect of condition revealed that compared to baseline, AP amplitude was elevated while asynchronous APs were reduced in early and late recovery, respectively. Our findings show that AP amplitude distributions are shifting towards larger AP amplitudes in all subjects following hypoxia. Our findings indicate that hypoxia-induced sLTF is mediated by baroreflex resetting of AP clusters to higher OPs, reduced asynchronous AP firing, and increased contribution from large-amplitude APs. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, Canada
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Canada
| | | | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, 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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13
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Mayr AK, Wieser V, Funk GC, Asadi S, Sperk I, Urban MH, Valipour A. Impaired Spontaneous Baroreceptor Reflex Sensitivity in Patients With COPD Compared to Healthy Controls: The Role of Lung Hyperinflation. Front Med (Lausanne) 2022; 8:791410. [PMID: 35047532 PMCID: PMC8761648 DOI: 10.3389/fmed.2021.791410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
Background and Objectives: Patients with chronic obstructive pulmonary disease (COPD) are at increased risk for cardiovascular disease. This study aimed to investigate the relationship between pulmonary hyperinflation and baroreceptor reflex sensitivity (BRS), a surrogate for cardiovascular risk. Methods: 33 patients with COPD, free from clinical cardiovascular disease, and 12 healthy controls were studied. Participants underwent pulmonary function and non-invasive hemodynamic measurements. BRS was evaluated using the sequence method during resting conditions and mental arithmetic stress testing. Results: Patients with COPD had evidence of airflow obstruction [forced expiratory volume in 1 s predicted (FEV1%) 26.5 (23.3-29.1) vs. 91.5 (82.8-100.8); P < 0.001; geometric means (GM) with 95% confidence interval (CI)] and lung hyperinflation [residual volume/total lung capacity (RV/TLC) 67.7 (64.3-71.3) vs. 41.0 (38.8-44.3); P < 0.001; GM with 95% CI] compared to controls. Spontaneous mean BRS (BRSmean) was significantly lower in COPD, both during rest [5.6 (4.2-6.9) vs. 12.0 (9.1-17.6); P = 0.003; GM with 95% CI] and stress testing [4.4 (3.7-5.3) vs. 9.6 (7.7-12.2); P < 0.001; GM with 95% CI]. Stroke volume (SV) was significantly lower in the patient group [-21.0 ml (-29.4 to -12.6); P < 0.001; difference of the means with 95% CI]. RV/TLC was found to be a predictor of BRS and SV (P < 0.05 for both), independent of resting heart rate. Conclusion: We herewith provide evidence of impaired BRS in patients with COPD. Hyperinflation may influence BRS through alteration of mechanosensitive vagal nerve activity.
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Affiliation(s)
- Anna Katharina Mayr
- Karl Landsteiner Institute for Lung Research and Pulmonary Oncology, Vienna, Austria.,Department of Internal and Respiratory Medicine, Klinik Floridsdorf, Vienna, Austria
| | - Victoria Wieser
- Department of Emergency Medicine, Klinik Hietzing, Vienna, Austria
| | - Georg-Christian Funk
- Karl Landsteiner Institute for Lung Research and Pulmonary Oncology, Vienna, Austria.,Department of Internal and Respiratory Medicine, Klinik Ottakring, Vienna, Austria
| | - Sherwin Asadi
- Department of Pediatrics, Klinik Donaustadt, Vienna, Austria
| | - Irene Sperk
- Karl Landsteiner Institute for Lung Research and Pulmonary Oncology, Vienna, Austria.,Department of Internal and Respiratory Medicine, Klinik Floridsdorf, Vienna, Austria
| | - Matthias Helmut Urban
- Karl Landsteiner Institute for Lung Research and Pulmonary Oncology, Vienna, Austria.,Department of Internal and Respiratory Medicine, Klinik Floridsdorf, Vienna, Austria
| | - Arschang Valipour
- Karl Landsteiner Institute for Lung Research and Pulmonary Oncology, Vienna, Austria.,Department of Internal and Respiratory Medicine, Klinik Floridsdorf, Vienna, Austria
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14
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Shafer BM, Incognito AV, Vermeulen TD, Nardone M, Teixeira AL, Benbaruj J, Millar PJ, Foster GE. Muscle Metaboreflex Control of Sympathetic Activity Is Preserved after Acute Intermittent Hypercapnic Hypoxia. Med Sci Sports Exerc 2021; 53:2233-2244. [PMID: 34081056 DOI: 10.1249/mss.0000000000002716] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE In normotensive patients with obstructive sleep apnea (OSA), the muscle sympathetic nerve activity (MSNA) response to exercise is increased while metaboreflex control of MSNA is decreased. We tested the hypotheses that acute intermittent hypercapnic hypoxia (IHH) in males free from OSA and associated comorbidities would augment the MSNA response to exercise but attenuate the change in MSNA during metaboreflex activation. METHODS Thirteen healthy males (age = 24 ± 4 yr) were exposed to 40 min of IHH. Before and after IHH, the pressor response to exercise was studied during 2 min of isometric handgrip exercise (at 30% maximal voluntary contraction), whereas the metaboreflex was studied during 4 min of postexercise circulatory occlusion (PECO). Mean arterial pressure (MAP), heart rate (HR), and fibular MSNA were recorded continuously. MSNA was quantified as burst frequency (BF) and total activity (TA). Mixed effects linear models were used to compare the exercise pressor and metaboreflex before and after IHH. RESULTS As expected, IHH led to significant increases in MSNA BF, TA, and MAP at baseline and throughout exercise and PECO. However, during handgrip exercise, the change from baseline in MAP, HR, MSNA BF, and TA was similar before and after IHH (All P > 0.31). During PECO, the change from baseline in MSNA BF and TA was similar after IHH, whereas the change from baseline in MAP (Δ14 mm Hg, 95% CI = 7-19, vs Δ16 mm Hg, 95% CI = 10-21; P < 0.01) was modestly increased. CONCLUSION After acute IHH, MSNA response to handgrip exercise and metaboreflex activation were preserved in healthy young males despite overall increases in resting MSNA and MAP. Chronic IHH and comorbidities often associated with OSA may be required to modulate the exercise pressor reflex and metaboreflex.
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Affiliation(s)
- Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Anthony V Incognito
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Massimo Nardone
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - André L Teixeira
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Jenna Benbaruj
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
| | - Philip J Millar
- Department of Human Health and Nutritional Sciences, University of Guelph, Ontario, CANADA
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, CANADA
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15
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Spector S, Debi R. Worth the risk? Effects of prolonged hypoxia and hypercapnia on ventilatory responses in patients with bilateral resection of the carotid bodies. J Physiol 2021; 599:3637-3638. [PMID: 34101181 DOI: 10.1113/jp281549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Steven Spector
- Department of Biology, York University, Toronto, ON, Canada
| | - Ryan Debi
- Department of Biology, York University, Toronto, ON, Canada
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16
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Marmarelis V, Shin D, Zhang R. Closed-Loop Dynamic Modeling of the Heart-Rate Reflex to Concurrent Spontaneous Changes of Arterial Blood Pressure and CO2 Tension: Quantification of the Effects of Mild Cognitive Impairment. IEEE Trans Biomed Eng 2021; 68:3347-3355. [PMID: 33819147 DOI: 10.1109/tbme.2021.3070900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To extend closed-loop modeling of the heart-rate reflex (HRR) by including the dynamic effects of concurrent changes in blood CO2 tension. This extended dynamic model can be used to generate physio-markers of "baroreflex gain" (BRG) and "chemoreflex gain" (CRG) that allow quantitative assessment of the possible impact of pathologies upon HRR. Mild Cognitive Impairment (MCI) is used as an example. METHODS The proposed data-based closed-loop modeling methodology estimates the forward and reverse dynamic components of the model via Laguerre kernel expansions of two open-loop models using spontaneous time-series data collected in 45 MCI patients and 15 controls. The BRG and CRG physio-markers are subsequently computed for each subject via simulation of the obtained closed-loop model for unit-step change of arterial pressure or blood CO2 tension, respectively. RESULTS Both open-loop and closed-loop HRR modeling revealed that MCI patients exhibit significantly smaller CRG relative to controls (p<0.001), but not significantly different BRG. Furthermore, the closed-loop model captured the dynamic effect of sympathetic activity as resonant peak around 0.1 Hz (Mayer wave) in the chemoreflex and baroreflex transfer functions (not captured via open-loop modeling). This may prove valuable in advancing our understanding of how sympathetic activity impacts HRR in various pathologies. CONCLUSION The extended HRR model, incorporating the dynamic effects of concurrent changes of blood CO2 tension, revealed significantly reduced chemoreflex gain (but not baroreflex gain) in MCI patients. Furthermore, the closed-loop model captured the sympathetic influence around 0.1 Hz. SIGNIFICANCE Multivariate closed-loop dynamic modeling is valuable for understanding physiological autoregulation.
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17
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Gatterer H, Menz V, Burtscher M. Acute Moderate Hypoxia Reduces One-Legged Cycling Performance Despite Compensatory Increase in Peak Cardiac Output: A Pilot Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18073732. [PMID: 33918381 PMCID: PMC8038296 DOI: 10.3390/ijerph18073732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 01/23/2023]
Abstract
In severe hypoxia, single-leg peak oxygen uptake (VO2peak) is reduced mainly due to the inability to increase cardiac output (CO). Whether moderate altitude allows CO to increase during single-leg cycling, thereby restoring VO2peak, has not been extensively investigated. Five healthy subjects performed an incremental, maximal, two-legged cycle ergometer test, and on separate days a maximal incremental one-leg cycling test in normoxia and in moderate hypoxia (fraction of inspired oxygen (FiO2) = 15%). Oxygen uptake, heart rate, blood pressure responses, power output, and CO (PhysioFlow) were measured during all tests. Moderate hypoxia lowered single-leg peak power output (154 ± 31 vs. 128 ± 26 watts, p = 0.03) and oxygen uptake (VO2) (36.8 ± 6.6 vs. 33.9 ± 6.9 mL/min/kg, p = 0.04), despite higher peak CO (16.83 ± 3.10 vs. 18.96 ± 3.59 L/min, p = 0.04) and systemic oxygen (O2) delivery (3.37 ± 0.84 vs. 3.47 ± 0.89 L/min, p = 0.04) in hypoxia compared to normoxia. Arterial–venous O2 difference (a–vDO2) was lower in hypoxia (137 ± 21 vs. 112 ± 19 mL/l, p = 0.03). The increases in peak CO from normoxia to hypoxia were negatively correlated with changes in mean arterial pressure (MABP) (p < 0.05). These preliminary data indicate that the rise in CO was not sufficient to prevent single-leg performance loss at moderate altitude and that enhanced baroreceptor activity might limit CO increases in acute hypoxia, likely by reducing sympathetic activation. Since the systemic O2 delivery was enhanced and the calculated a–vDO2 reduced in moderate hypoxia, a potential diffusion limitation cannot be excluded.
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Affiliation(s)
- Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, 39100 Bolzano, Italy
- Correspondence:
| | - Verena Menz
- Department of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria; (V.M.); (M.B.)
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria; (V.M.); (M.B.)
- Austrian Society for High Altitude and Mountain Medicine, 6020 Innsbruck, Austria
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18
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Headid RJ, Pekas EJ, Wooden TK, Son WM, Layec G, Shin J, Park SY. Impacts of prolonged sitting with mild hypercapnia on vascular and autonomic function in healthy recreationally active adults. Am J Physiol Heart Circ Physiol 2020; 319:H468-H480. [PMID: 32648821 DOI: 10.1152/ajpheart.00354.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Prolonged sitting, which is known to impair peripheral vascular function, often occurs in spaces (e.g., offices) with mild hypercapnic atmospheres. However, the effects of prolonged sitting in hypercapnic conditions on vascular function are unknown. Therefore, the purpose of this study was to investigate the effects of prolonged sitting in mild hypercapnic conditions on vascular and autonomic function in humans. Twelve healthy young adults participated in two experimental visits that consisted of sitting for 2.5 h in a control condition [normal atmospheric conditions sitting (PSIT)] or a mild hypercapnic condition (HCAP; CO2 = 1,500 ppm). During each visit, heart rate variability (HRV), blood pressure (BP), pulse wave velocity (PWV), augmentation index (AIx), brachial and popliteal artery flow-mediated dilation (FMD), and near-infrared spectroscopy (NIRS) were assessed before and after prolonged sitting. Sitting significantly decreased AIx in both groups (P < 0.05). Brachial and popliteal FMD were reduced with sitting (P < 0.05), and the reduction in popliteal FMD was amplified by HCAP (P < 0.05). Baseline microvascular oxygenation was decreased following sitting in both groups (P < 0.05). However, microvascular reoxygenation upon cuff release was slower only in HCAP (P < 0.05). HRV, HR, BP, and PWV did not significantly change with sitting in either group (P > 0.05). We conclude that prolonged sitting attenuated both brachial and popliteal endothelial function and was associated with perturbed microcirculation. Additionally, mild hypercapnic conditions further impaired peripheral endothelial and microvascular function. Together, these findings suggest that prolonged sitting is accompanied by a host of deleterious effects on the vasculature, which are exacerbated by mild hypercapnia.NEW & NOTEWORTHY The results of this study reveal that prolonged sitting attenuates endothelial function and microvascular function. Additionally, prolonged sitting with mild hypercapnia, which is similar to everyday environments, further exacerbates peripheral endothelial function and microvascular function.
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Affiliation(s)
- Ronald J Headid
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska
| | - Elizabeth J Pekas
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska
| | - TeSean K Wooden
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska
| | - Won-Mok Son
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska
| | - Gwenael Layec
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts.,Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts
| | - John Shin
- Wiess School of Natural Sciences, Rice University, Houston, Texas
| | - Song-Young Park
- School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska
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19
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Hamaoka T, Murai H, Takata S, Hirai T, Sugimoto H, Mukai Y, Okabe Y, Tokuhisa H, Takashima SI, Usui S, Sakata K, Kawashiri MA, Sugiyama Y, Nakatsumi Y, Takamura M. Different prognosis between severe and very severe obstructive sleep apnea patients; Five year outcomes. J Cardiol 2020; 76:573-579. [PMID: 32620307 DOI: 10.1016/j.jjcc.2020.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 04/26/2020] [Accepted: 05/25/2020] [Indexed: 11/27/2022]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) is characterized by augmented sympathetic nerve activity. In our previous study, patients with OSA and an apnea-hyperpnea index (AHI)>55events/h showed increased single-unit muscle sympathetic nerve activity compared to patients with OSA and AHI of 30-55events/h. However, the prognostic impact in these patients remains unclear. METHODS Ninety-one OSA patients were included. All patients who had indication for continuous positive airway pressure (CPAP) were treated with CPAP. Patients were divided into three groups: mild/moderate OSA (S), AHI<30events/h (n=44); severe OSA (SS), AHI 30-55events/h (n=29); and very severe OSA (VSS), AHI>55events/h (n=18). The primary endpoint was a composite outcome composed of death, cardiovascular events, stroke, and heart failure with hospitalization. RESULTS In the 5-year follow-up, the primary event rate in the SS group [3 events (7%)] was the same as that in the S group [3 events (10%)]. However, the VSS group showed a significantly higher primary event rate among the three groups [6 events (33%), p<0.05]. In Cox regression analysis, the VSS group had the highest hazard ratio compared to other risk factors. CONCLUSIONS CPAP was effective for preventing cardiovascular disease in patients with severe OSA, however patients with very severe OSA still had a high event rate, indicating that CPAP treatment might be insufficient to reduce the OSA-related risk burden in patients with very severe OSA. Additional systemic medical treatment for CPAP might be needed in patients with very severe OSA.
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Affiliation(s)
- Takuto Hamaoka
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hisayoshi Murai
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan; Kanazawa Municipal Hospital, Kanazawa, Japan.
| | | | - Tadayuki Hirai
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hiroyuki Sugimoto
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Yusuke Mukai
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Yoshitaka Okabe
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Hideki Tokuhisa
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Shin-Ichiro Takashima
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Soichiro Usui
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Kenji Sakata
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Masa-Aki Kawashiri
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Yu Sugiyama
- Kanazawa Municipal Hospital, Kanazawa, Japan
| | | | - Masayuki Takamura
- Department of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
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20
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Wan HY, Weavil JC, Thurston TS, Georgescu VP, Hureau TJ, Bledsoe AD, Buys MJ, Jessop JE, Richardson RS, Amann M. The exercise pressor reflex and chemoreflex interaction: cardiovascular implications for the exercising human. J Physiol 2020; 598:2311-2321. [PMID: 32170732 DOI: 10.1113/jp279456] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/10/2020] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Although the exercise pressor reflex (EPR) and the chemoreflex (CR) are recognized for their sympathoexcitatory effect, the cardiovascular implication of their interaction remains elusive. We quantified the individual and interactive cardiovascular consequences of these reflexes during exercise and revealed various modes of interaction. The EPR and hypoxia-induced CR interaction is hyper-additive for blood pressure and heart rate (responses during co-activation of the two reflexes are greater than the summation of the responses evoked by each reflex) and hypo-additive for peripheral haemodynamics (responses during co-activation of the reflexes are smaller than the summated responses). The EPR and hypercapnia-induced CR interaction results in a simple addition of the individual responses to each reflex (i.e. additive interaction). Collectively, EPR:CR co-activation results in significant cardiovascular interactions with restriction in peripheral haemodynamics, resulting from the EPR:CR interaction in hypoxia, likely having the most crucial impact on the functional capacity of an exercising human. ABSTRACT We investigated the interactive effect of the exercise pressor reflex (EPR) and the chemoreflex (CR) on the cardiovascular response to exercise. Eleven healthy participants (5 females) completed a total of six bouts of single-leg knee-extension exercise (60% peak work rate, 4 min each) either with or without lumbar intrathecal fentanyl to attenuate group III/IV afferent feedback from lower limbs to modify the EPR, while breathing either ambient air, normocapnic hypoxia (Sa O2 ∼79%, Pa O2 ∼43 mmHg, Pa CO2 ∼33 mmHg, pH ∼7.39), or normoxic hypercapnia (Sa O2 ∼98%, Pa O2 ∼105 mmHg, Pa CO2 ∼50 mmHg, pH ∼7.26) to modify the CR. During co-activation of the EPR and the hypoxia-induced CR (O2 -CR), mean arterial pressure and heart rate were significantly greater, whereas leg blood flow and leg vascular conductance were significantly lower than the summation of the responses evoked by each reflex alone. During co-activation of the EPR and the hypercapnia-induced CR (CO2 -CR), the haemodynamic responses were not different from the summated responses to each reflex response alone (P ≥ 0.1). Therefore, while the interaction resulting from the EPR:O2 -CR co-activation is hyper-additive for blood pressure and heart rate, and hypo-additive for peripheral haemodynamics, the interaction resulting from the EPR:CO2 -CR co-activation is simply additive for all cardiovascular parameters. Thus, EPR:CR co-activation results in significant interactions between cardiovascular reflexes, with the impact differing when the CR activation is achieved by hypoxia or hypercapnia. Since the EPR:CR co-activation with hypoxia potentiates the pressor response and restricts blood flow to contracting muscles, this interaction entails the most functional impact on an exercising human.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Michael J Buys
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
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21
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Niebauer JH, Niebauer J, Wille M, Burtscher M. Systemic Blood Pressure Variation During a 12-Hour Exposure to Normobaric Hypoxia (4500 m). High Alt Med Biol 2020; 21:194-199. [PMID: 32186921 DOI: 10.1089/ham.2019.0130] [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: 11/13/2022] Open
Abstract
This study was aimed at evaluating a potential association between blood pressure variation and acute mountain sickness (AMS) during acute exposure to normobaric hypoxia. A total of 77 healthy subjects (43 males, 34 females) were exposed to a simulated altitude of 4500 m for 12 hours. Peripheral oxygen saturation, heart rate, systemic blood pressure, and Lake Louise AMS scores were recorded before and during (30 minutes, 3, 6, 9, and 12 hours) hypoxic exposure. Blood pressure dips were observed at 3-hour mark. However, systolic blood pressure fell more pronounced from baseline during the initial 30 minutes in normobaric hypoxia (-17.5 vs. -11.0 mmHg, p = 0.01) in subjects suffering from AMS (AMS+; n = 56) than in those remaining unaffected from AMS (AMS-; n = 21); values did not differ between groups over the subsequent time course. Our data may suggest a transient autonomic dysfunction resulting in a more pronounced blood pressure drop during initial hypoxic exposure in AMS+ compared with AMS- subjects.
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Affiliation(s)
| | - Josef Niebauer
- University Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Maria Wille
- Department of Sports Science, University of Innsbruck, Innsbruck, Austria
| | - Martin Burtscher
- Department of Sports Science, University of Innsbruck, Innsbruck, Austria.,Austrian Society for Alpine- and High-Altitude Medicine, Innsbruck, Austria
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22
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Testing individual baroreflex responses to hypoxia-induced peripheral chemoreflex stimulation. Clin Auton Res 2020; 30:531-540. [PMID: 31974825 PMCID: PMC7704522 DOI: 10.1007/s10286-019-00660-6] [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: 09/13/2019] [Accepted: 12/21/2019] [Indexed: 12/24/2022]
Abstract
Introduction Baroreflexes and peripheral chemoreflexes control efferent autonomic activity making these reflexes treatment targets for arterial hypertension. The literature on their interaction is controversial, with suggestions that their individual and collective influence on blood pressure and heart rate regulation is variable. Therefore, we applied a study design that allows the elucidation of individual baroreflex–chemoreflex interactions. Methods We studied nine healthy young men who breathed either normal air (normoxia) or an air–nitrogen–carbon dioxide mixture with decreased oxygen content (hypoxia) for 90 min, with randomization to condition, followed by a 30-min recovery period and then exposure to the other condition for 90 min. Multiple intravenous phenylephrine bolus doses were applied per condition to determine phenylephrine pressor sensitivity as an estimate of baroreflex blood pressure buffering and cardiovagal baroreflex sensitivity (BRS). Results Hypoxia reduced arterial oxygen saturation from 98.1 ± 0.4 to 81.0 ± 0.4% (p < 0.001), raised heart rate from 62.9 ± 2.1 to 76.0 ± 3.6 bpm (p < 0.001), but did not change systolic blood pressure (p = 0.182). Of the nine subjects, six had significantly lower BRS in hypoxia (p < 0.05), two showed a significantly decreased pressor response, and three showed a significantly increased pressor response to phenylephrine in hypoxia, likely through reduced baroreflex buffering (p < 0.05). On average, hypoxia decreased BRS by 6.4 ± 0.9 ms/mmHg (19.9 ± 2.0 vs. 14.12 ± 1.6 ms/mmHg; p < 0.001) but did not change the phenylephrine pressor response (p = 0.878). Conclusion We applied an approach to assess individual baroreflex–chemoreflex interactions in human subjects. A subgroup exhibited significant impairments in baroreflex blood pressure buffering and BRS with peripheral chemoreflex activation. The methodology may have utility in elucidating individual pathophysiology and in targeting treatments modulating baroreflex or chemoreflex function.
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23
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Bourdillon N, Yazdani S, Vesin JM, Subudhi AW, Lovering AT, Roach RC, Kayser B. AltitudeOmics: Spontaneous Baroreflex Sensitivity During Acclimatization to 5,260 m: A Comparison of Methods. Front Physiol 2020; 10:1505. [PMID: 31920710 PMCID: PMC6914841 DOI: 10.3389/fphys.2019.01505] [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: 09/04/2019] [Accepted: 11/28/2019] [Indexed: 11/13/2022] Open
Abstract
Introduction Baroreflex sensitivity (BRS) is essential to ensure rapid adjustment to variations in blood pressure (BP). Spontaneous baroreflex function can be assessed using continuous recordings of blood pressure. The goal of this study was to compare four methods for BRS quantification [the sequence, Bernardi's (BER), frequency and transfer function methods] to identify the most consistent method across an extreme range of conditions: rest and exercise, in normoxia, hypoxia, hypocapnia, and hypercapnia. Methods Using intra-radial artery BP in young healthy participants, BRS was calculated and compared using the four methods in normoxia, acute and chronic hypoxia (terrestrial altitude of 5,260 m) in hypocapnia (hyperventilation), hypercapnia (rebreathing) and during ramp exercise to exhaustion. Results The sequence and BER methods for BRS estimation showed good agreement during the resting and exercise protocols, whilst the ultra- and very-low frequency bands of the frequency and transfer function methods were more discrepant. Removing respiratory frequency from the blood pressure traces affected primarily the sequence and BER methods and occasionally the frequency and transfer function methods. Discussion/Conclusion The sequence and BER methods contained more respiratory related information than the frequency and transfer function methods, indicating that the former two methods predominantly rely on respiratory effects of BRS. BER method is recommended because it is the easiest to compute and even though it tends to overestimate BRS compared to the sequence method, it is consistent with the other methods, whilst its interquartile range is the smallest.
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Affiliation(s)
- Nicolas Bourdillon
- Institue of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Sasan Yazdani
- Applied Signal Processing Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Andrew W Subudhi
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.,Human Physiology and Nutrition, University of Colorado Colorado Springs, Colorado Springs, CO, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Robert C Roach
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Bengt Kayser
- Institue of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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24
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Affiliation(s)
- Horacio Kaufmann
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
| | - Lucy Norcliffe-Kaufmann
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
| | - Jose-Alberto Palma
- From the Department of Neurology, Dysautonomia Center, New York University School of Medicine, New York
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25
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Lin HY, Su PL, Lin CY, Hung CH. Models of anatomically based oropharyngeal rehabilitation with a multilevel approach for patients with obstructive sleep apnea: a meta-synthesis and meta-analysis. Sleep Breath 2019; 24:1279-1291. [PMID: 31836993 DOI: 10.1007/s11325-019-01971-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/17/2019] [Accepted: 11/02/2019] [Indexed: 12/12/2022]
Abstract
OBJECTIVES Obstructive sleep apnea (OSA) is a sleep-related breathing disorder associated with dysfunction of oropharyngeal muscles to maintain upper airway patency during sleep. Oropharyngeal rehabilitation (OPR) was developed to restore, reconstruct, and reeducate oropharyngeal muscle function, but current protocols and effectiveness of OPR have been inconsistent. The purpose of this study was to review (1) indications of OPR, (2) protocols of OPR, and (3) effectiveness of OPR. METHODS We searched MEDLINE, EMBASE, and the Cochrane Library and then conducted both meta-synthesis and meta-analysis according to the statement of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). RESULTS A total of eight studies with 203 patients were included. By means of meta-synthesis, the patients with middle age, BMI < 40 kg/m2, mild-to-moderate OSA, and non-severe upper airway anatomical abnormality were found to benefit from OPR. The protocol of OPR was summarized to be an anatomically based, multilevel approach, including the retropalatal, retroglossal, hypopharyngeal, TMJ, and facial levels. By using meta-analysis, overall outcomes were presented as apnea hypopnea index (AHI) with significant improvement from 25.2 ± 7.8/h to 16.1 ± 6.6/h (mean difference [MD] - 9.8 [95% CI - 11.0 to - 8.6], p < 0.0001); the lowest oxygen saturation (LSAT) improved from 80.2 ± 4.7 to 83.8 ± 2.9% (MD 3.0% [95% CI 2.0 to 4.0], p < 0.0001); Epworth sleepiness scale (ESS) improved from 11.8 ± 1.9 to 6.3 ± 1.6 (MD - 5.9 [95% CI - 7.5 to - 4.2], p < 0.001), neck circumference (NC) from 35.2 ± 1.1 to 34.7 ± 0.9 cm (MD - 0.6 [95% CI - 0.9 to - 0.2], p = 0.002), BMI from 24.8 ± 3.7 to 24.8 ± 4.1 kg/m2 (MD - 0.0; 95% CI - 0.5 to 0.5, p = 0.95). All outcomes except BMI demonstrated significant improvement from OPR. CONCLUSIONS Meta-analysis of previous OPR reports shows an improvement in AHI of 39%, compared with the usual surgical definition of success at 50%. Only mild and moderate cases of OSA were referred for OPR in the prior studies. In order to improve outcomes with OPR, a comprehensive approach to rehabilitation should be emphasized.
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Affiliation(s)
- Hsin-Yu Lin
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, No. 1 Ta-Hsueh Road, East District, Tainan City, 701, Taiwan
| | - Po-Lan Su
- Department of Internal Medicine, Division of Pulmonary, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138, Sheng-Li Road, North District, Tainan City, 704, Taiwan
| | - Cheng-Yu Lin
- Department of Otolaryngology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138, Sheng-Li Road, North District, Tainan City, 704, Taiwan.,Department of Environmental and Occupational Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138, Sheng-Li Road, North District, Tainan City, 704, Taiwan.,Sleep Medicine Center, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138, Sheng-Li Road, North District, Tainan City, 704, Taiwan
| | - Ching-Hsia Hung
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, No. 1 Ta-Hsueh Road, East District, Tainan City, 701, Taiwan. .,Department of Physical Therapy, College of Medicine, National Cheng Kung University, No. 1 Ta-Hsueh Road, East District, Tainan City, 701, Taiwan.
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26
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Heusser K, Thöne A, Lipp A, Menne J, Beige J, Reuter H, Hoffmann F, Halbach M, Eckert S, Wallbach M, Koziolek M, Haarmann H, Joyner MJ, Paton JFR, Diedrich A, Haller H, Jordan J, Tank J. Efficacy of Electrical Baroreflex Activation Is Independent of Peripheral Chemoreceptor Modulation. Hypertension 2019; 75:257-264. [PMID: 31786986 DOI: 10.1161/hypertensionaha.119.13925] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Arterial baroreflex activation through electrical carotid sinus stimulation has been developed for the treatment of resistant hypertension. Previous studies suggested that the peripheral chemoreflex is tonically active in hypertensive patients and may inhibit baroreflex responses. We hypothesized that peripheral chemoreflex activation attenuates baroreflex efficacy evoked by electrical carotid sinus stimulation. We screened 35 patients with an implanted electrical carotid sinus stimulator. Of those, 11 patients with consistent acute depressor response were selected (7 men/4 women, age: 67±8 years, body mass index: 31.6±5.2 kg/m2, 6±2 antihypertensive drug classes). We assessed responses to electrical baroreflex stimulation during normoxia, isocapnic hypoxia (SpO2: 79.0±1.5%), and hyperoxia (40% end-tidal O2 fraction) by measuring heart rate, blood pressure, ventilation, oxygen saturation, end-tidal CO2 and O2 fractions, and muscle sympathetic nerve activity. During normoxia, baroreflex activation reduced systolic blood pressure from 164±27 to 151±25 mm Hg (mean±SD, P<0.001), heart rate from 64±13 to 61±13 bpm (P=0.002), and muscle sympathetic nerve activity from 42±12 to 36±12 bursts/min (P=0.004). Hypoxia increased systolic blood pressure 8±12 mm Hg (P=0.057), heart rate 10±6 bpm (P<0.001), muscle sympathetic nerve activity 7±7 bursts/min (P=0.031), and ventilation 10±7 L/min (P=0.002). However, responses to electrical carotid sinus stimulation did not differ between hypoxic and hyperoxic conditions: systolic blood pressure: -15±7 versus -14±8 mm Hg (P=0.938), heart rate: -2±3 versus -2±2 bpm (P=0.701), and muscle sympathetic nerve activity: -6±4 versus -4±3 bursts/min (P=0.531). We conclude that moderate peripheral chemoreflex activation does not attenuate acute responses to electrical baroreflex activation therapy in patients with resistant hypertension. These patients provided insight into human baroreflex-chemoreflex interactions that could not be gained otherwise.
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Affiliation(s)
- Karsten Heusser
- From the Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (K.H., F.H., J.J., J.T.)
| | | | - Axel Lipp
- Department of Neurology, Park Clinic Weissensee, Berlin, Germany (A.L.)
| | - Jan Menne
- Department of Nephrology and Hypertensiology, Hannover Medical School, Germany (J.M., H. Haller)
| | - Joachim Beige
- Department of Nephrology and KfH Renal Unit, Hospital St. Georg, Leipzig, Germany (J.B.).,Faculty of Medicine, Martin Luther University Halle/Wittenberg, Germany (J.B.)
| | - Hannes Reuter
- Department of Cardiology, Pneumology, and Angiology, Heart Center of the University of Cologne, Germany (H.R., F.H., M.H.).,Department of Internal Medicine, Ev. Klinikum Köln Weyertal, Cologne, Germany (H.R.)
| | - Fabian Hoffmann
- From the Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (K.H., F.H., J.J., J.T.).,Department of Cardiology, Pneumology, and Angiology, Heart Center of the University of Cologne, Germany (H.R., F.H., M.H.)
| | - Marcel Halbach
- Department of Cardiology, Pneumology, and Angiology, Heart Center of the University of Cologne, Germany (H.R., F.H., M.H.)
| | - Siegfried Eckert
- Department of Cardiology, Heart and Diabetes Centre North Rhine-Westphalia, University Hospital, Ruhr University Bochum, Bad Oeynhausen, Germany (S.E.)
| | - Manuel Wallbach
- Department of Nephrology & Rheumatology (M.W., M.K.), University Medical Center Göttingen, Germany
| | - Michael Koziolek
- Department of Nephrology & Rheumatology (M.W., M.K.), University Medical Center Göttingen, Germany
| | - Helge Haarmann
- Clinic for Cardiology and Pneumology (H.Haarmann), University Medical Center Göttingen, Germany
| | - Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, Rochester, MN (M.J.J.)
| | - Julian F R Paton
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, United Kingdom (J.F.R.P.).,Department of Physiology, University of Auckland, Grafton, New Zealand (J.F.R.P.)
| | - André Diedrich
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University Medical Center, Nashville, TN (A.D.)
| | - Hermann Haller
- Department of Nephrology and Hypertensiology, Hannover Medical School, Germany (J.M., H. Haller)
| | - Jens Jordan
- From the Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (K.H., F.H., J.J., J.T.)
| | - Jens Tank
- From the Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (K.H., F.H., J.J., J.T.)
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27
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Huang CC, Lin HC, Lai YR, Tsai NW, Lin WC, Wang HC, Kung CT, Cheng BC, Su YJ, Su CM, Hsiao SY, Lu CH. Long-term effects of surgical treatment on baroreflex function in patients with obstructive sleep apnea: an 18-month follow-up. Sleep Med 2019; 60:152-158. [DOI: 10.1016/j.sleep.2019.03.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 01/17/2019] [Accepted: 03/12/2019] [Indexed: 10/27/2022]
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28
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Keir DA, Duffin J, Millar PJ, Floras JS. Simultaneous assessment of central and peripheral chemoreflex regulation of muscle sympathetic nerve activity and ventilation in healthy young men. J Physiol 2019; 597:3281-3296. [DOI: 10.1113/jp277691] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/13/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Daniel A. Keir
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
| | - James Duffin
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
| | - Philip J. Millar
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
- Human Health and Nutritional ScienceUniversity of Guelph Guelph Ontario Canada
| | - John S. Floras
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
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29
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Assessment of Baroreflex Sensitivity Using Time-Frequency Analysis during Postural Change and Hypercapnia. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:4875231. [PMID: 30863454 PMCID: PMC6377966 DOI: 10.1155/2019/4875231] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/16/2018] [Accepted: 01/06/2019] [Indexed: 01/09/2023]
Abstract
Baroreflex is a mechanism of short-term neural control responsible for maintaining stable levels of arterial blood pressure (ABP) in an ABP-heart rate negative feedback loop. Its function is assessed by baroreflex sensitivity (BRS)—a parameter which quantifies the relationship between changes in ABP and corresponding changes in heart rate (HR). The effect of postural change as well as the effect of changes in blood O2 and CO2 have been the focus of multiple previous studies on BRS. However, little is known about the influence of the combination of these two factors on dynamic baroreflex response. Furthermore, classical methods used for BRS assessment are based on the assumption of stationarity that may lead to unreliable results in the case of mostly nonstationary cardiovascular signals. Therefore, we aimed to investigate BRS during repeated transitions between squatting and standing in normal end-tidal CO2 (EtCO2) conditions (normocapnia) and conditions of progressively increasing EtCO2 with a decreasing level of O2 (hypercapnia with hypoxia) using joint time and frequency domain (TF) approach to BRS estimation that overcomes the limitation of classical methods. Noninvasive continuous measurements of ABP and EtCO2 were conducted in a group of 40 healthy young volunteers. The time course of BRS was estimated from TF representations of pulse interval variability and systolic pressure variability, their coherence, and phase spectra. The relationship between time-variant BRS and indices of ABP and HR was analyzed during postural change in normocapnia and hypercapnia with hypoxia. In normocapnia, observed trends in all measures were in accordance with previous studies, supporting the validity of presented TF method. Similar but slightly attenuated response to postural change was observed in hypercapnia with hypoxia. Our results show the merits of the nonstationary methods as a tool to study the cardiovascular system during short-term hemodynamic changes.
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30
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Bourdillon N, Yazdani S, Subudhi AW, Lovering AT, Roach RC, Vesin JM, Kayser B. AltitudeOmics: Baroreflex Sensitivity During Acclimatization to 5,260 m. Front Physiol 2018; 9:767. [PMID: 29977210 PMCID: PMC6021743 DOI: 10.3389/fphys.2018.00767] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 05/31/2018] [Indexed: 11/13/2022] Open
Abstract
Introduction: Baroreflex sensitivity (BRS) is essential to ensure rapid adjustment to variations in blood pressure (BP). Little is known concerning the adaptive responses of BRS during acclimatization to high altitude at rest and during exercise. Methods: Twenty-one healthy sea-level residents were tested near sea level (SL, 130 m), the 1st (ALT1) and 16th day (ALT16) at 5,260 m using radial artery catheterization. BRS was calculated using the sequence method (direct interpretation of causal link between BP and heartrate). At rest, subjects breathed a hyperoxic mixture (250 mmHg O2, end tidal) to isolate the preponderance of CO2 chemoreceptors. End-tidal CO2 varied from 20 to 50 mmHg to assess peripheral chemoreflex. Rebreathing provoked incremental increase in CO2, increasing BP to assess baroreflex. During incremental cycling exercise to exhaustion, subjects breathed room air. Results: Resting BRS decreased in ALT1 which was exacerbated in ALT16. This decrease in ALT1 was reversible upon additional inspired CO2, but not in ALT16. BRS decrease during exercise was greater and occurred at lower workloads in ALT1 compared to SL. At ALT16, this decrease returned toward SL values. Discussion/Conclusion: This study is the first to report attenuated BRS in acute hypoxia, exacerbated in chronic hypoxia. In ALT1, hypocapnia triggered BRS reduction whilst in ALT16 resetting of chemoreceptor triggered BRS reduction. The exercise BRS resetting was impaired in ALT1 but normalized in ALT16. These BRS decreases indicate decreased control of BP and may explain deteriorations of cardiovascular status during exposure to high altitude.
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Affiliation(s)
- Nicolas Bourdillon
- Institute of Sports Sciences of the University of Lausanne, Lausanne, Switzerland
| | - Sasan Yazdani
- Applied Signal Processing Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Andrew W Subudhi
- Department of Biology, University of Colorado, Colorado Springs, CO, United States.,Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Robert C Roach
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Bengt Kayser
- Institute of Sports Sciences of the University of Lausanne, Lausanne, Switzerland
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31
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Armoni Domany K, Hossain MM, Nava-Guerra L, Khoo MC, McConnell K, Carroll JL, Xu Y, DiFrancesco M, Amin RS. Cardioventilatory Control in Preterm-born Children and the Risk of Obstructive Sleep Apnea. Am J Respir Crit Care Med 2018; 197:1596-1603. [PMID: 29323933 PMCID: PMC6006399 DOI: 10.1164/rccm.201708-1700oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/09/2018] [Indexed: 12/16/2022] Open
Abstract
RATIONALE The contribution of ventilatory control to the pathogenesis of obstructive sleep apnea (OSA) in preterm-born children is unknown. OBJECTIVES To characterize phenotypes of ventilatory control that are associated with the presence of OSA in preterm-born children during early childhood. METHODS Preterm- and term-born children without comorbid conditions were enrolled. They were categorized into an OSA group and a non-OSA group on the basis of polysomnography. MEASUREMENTS AND MAIN RESULTS Loop gain, controller gain, and plant gain, reflecting ventilatory instability, chemoreceptor sensitivity, and blood gas response to a change in ventilation, respectively, were estimated from spontaneous sighs identified during polysomnography. Cardiorespiratory coupling, a measure of brainstem maturation, was estimated by measuring the interval between inspiration and the preceding electrocardiogram R-wave. Cluster analysis was performed to develop phenotypes based on controller gain, plant gain, cardiorespiratory coupling, and gestational age. The study included 92 children, 63 of whom were born preterm (41% OSA) and 29 of whom were born at term (48% OSA). Three phenotypes of ventilatory control were derived with risks for OSA being 8%, 47%, and 77% in clusters 1, 2, and 3, respectively. There was a stepwise decrease in controller gain and an increase in plant gain from clusters 1 to 3. Children in cluster 1 had significantly higher cardiorespiratory coupling and gestational age than clusters 2 and 3. No difference in loop gain was found between clusters. CONCLUSIONS The risk for OSA could be stratified according to controller gain, plant gain, cardiorespiratory coupling, and gestational age. These findings could guide personalized care for children at risk for OSA.
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Affiliation(s)
- Keren Armoni Domany
- Division of Pulmonary Medicine
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Leonardo Nava-Guerra
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California; and
| | - Michael C. Khoo
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California; and
| | | | - John L. Carroll
- Division of Pediatric Pulmonary and Sleep Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Yuanfang Xu
- Division of Biostatistics and Epidemiology, and
| | - Mark DiFrancesco
- Pediatric Neuroimaging Research Consortium, Department of Radiology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio
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Abstract
Breath-hold diving is practiced by recreational divers, seafood divers, military divers, and competitive athletes. It involves highly integrated physiology and extreme responses. This article reviews human breath-hold diving physiology beginning with an historical overview followed by a summary of foundational research and a survey of some contemporary issues. Immersion and cardiovascular adjustments promote a blood shift into the heart and chest vasculature. Autonomic responses include diving bradycardia, peripheral vasoconstriction, and splenic contraction, which help conserve oxygen. Competitive divers use a technique of lung hyperinflation that raises initial volume and airway pressure to facilitate longer apnea times and greater depths. Gas compression at depth leads to sequential alveolar collapse. Airway pressure decreases with depth and becomes negative relative to ambient due to limited chest compliance at low lung volumes, raising the risk of pulmonary injury called "squeeze," characterized by postdive coughing, wheezing, and hemoptysis. Hypoxia and hypercapnia influence the terminal breakpoint beyond which voluntary apnea cannot be sustained. Ascent blackout due to hypoxia is a danger during long breath-holds, and has become common amongst high-level competitors who can suppress their urge to breathe. Decompression sickness due to nitrogen accumulation causing bubble formation can occur after multiple repetitive dives, or after single deep dives during depth record attempts. Humans experience responses similar to those seen in diving mammals, but to a lesser degree. The deepest sled-assisted breath-hold dive was to 214 m. Factors that might determine ultimate human depth capabilities are discussed. © 2018 American Physiological Society. Compr Physiol 8:585-630, 2018.
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Acute and chronic changes in baroreflex sensitivity in hypobaric vs. normobaric hypoxia. Eur J Appl Physiol 2017; 117:2401-2407. [PMID: 28956166 DOI: 10.1007/s00421-017-3726-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/21/2017] [Indexed: 12/21/2022]
Abstract
Normobaric hypoxia (NH) is used as a surrogate for hypobaric hypoxia (HH). Recent studies reported physiological differences between NH and HH. Baroreflex sensitivity (BRS) decreases at altitude or following intense training. However, until now no study compared the acute and chronic changes of BRS in NH vs. HH. First, BRS was assessed in 13 healthy male subjects prior and after 20 h of exposure at 3450 m (study 1), and second in 15 well-trained athletes prior and after 18 days of "live-high train-low" (LHTL) at 2250 m (study 2) in NH vs. HH. BRS decreased (p < 0.05) to the same extent in NH and HH after 20 h of hypoxia and after LHTL. These results confirm that altitude decreases BRS but the decrease is similar between HH and NH. The persistence of this decrease after the cessation of a chronic exposure is new and does not differ between HH and NH. The previously reported physiological differences between NH and HH do not appear strong enough to induce different BRS responses.
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Eskandari D, Zou D, Grote L, Schneider H, Penzel T, Hedner J. Independent associations between arterial bicarbonate, apnea severity and hypertension in obstructive sleep apnea. Respir Res 2017; 18:130. [PMID: 28659192 PMCID: PMC5490198 DOI: 10.1186/s12931-017-0607-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 06/08/2017] [Indexed: 01/01/2023] Open
Abstract
Background Obstructive sleep apnea is characterized by intermittent hypoxia and hypercapnia. CO2 production, transport and elimination are influenced by the carbonic anhydrase enzyme. We hypothesized that elevated standard bicarbonate, a proxy for increased carbonic anhydrase activity, is associated with apnea severity and higher blood pressure in patients with obstructive sleep apnea. Methods A retrospective analysis of a sleep apnea cohort (n = 830) studied by ambulatory polygraphy. Office systolic/diastolic blood pressure, lung function, and arterial blood gases were assessed during daytime. Results Arterial standard bicarbonate was increased with apnea severity (mild/moderate/severe 24.1 ± 1.8, 24.4 ± 1.7 and 24.9 ± 2.9 mmol/l, respectively, Kruskal-Wallis test p < 0.001). Standard bicarbonate was independently associated with apnea hypopnea index after adjustment for sex, age, body mass index, smoking, alcohol, hypertension, pO2 and pCO2 (standard bicarbonate quartile 1 vs. quartile 4, β = 10.6, p < 0.001). Log-transformed standard bicarbonate was associated with a diagnosis of hypertension or diastolic blood pressure but not systolic blood pressure adjusting for cofounders (p = 0.007, 0.048 and 0.45, respectively). Conclusions There was an independent association between sleep apnea severity and arterial standard bicarbonate. The link between high standard bicarbonate and daytime hypertension suggests that carbonic anhydrase activity may constitute a novel mechanism for blood pressure regulation in sleep apnea. Electronic supplementary material The online version of this article (doi:10.1186/s12931-017-0607-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Davoud Eskandari
- Center for Sleep and Vigilance Disorders, Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 8B, Box 421, SE-40530, Gothenburg, Sweden
| | - Ding Zou
- Center for Sleep and Vigilance Disorders, Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 8B, Box 421, SE-40530, Gothenburg, Sweden.
| | - Ludger Grote
- Center for Sleep and Vigilance Disorders, Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 8B, Box 421, SE-40530, Gothenburg, Sweden
| | - Hartmut Schneider
- Johns Hopkins Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Thomas Penzel
- Interdisciplinary Center of Sleep Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany.,International Clinical Research Center, St. Anne's University Hospital Brno, Brno, Czech Republic
| | - Jan Hedner
- Center for Sleep and Vigilance Disorders, Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 8B, Box 421, SE-40530, Gothenburg, Sweden
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Bartels W, Buck D, Glos M, Fietze I, Penzel T. Definition and Importance of Autonomic Arousal in Patients with Sleep Disordered Breathing. Sleep Med Clin 2016; 11:435-444. [PMID: 28118868 DOI: 10.1016/j.jsmc.2016.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Autonomic arousal at the end of sleep apnea events are not well-explored. We prospectively studied 20 patients with obstructive sleep apnea (OSA) and 24 healthy volunteers for 2 nights with cardiorespiratory polysomnography and continuous noninvasive blood pressure (Portapres). Recordings were scored visually for cortical and autonomic arousal. In the OSA group, 2151 cortical arousals and in the controls 1089 cortical arousals were scored. Respiratory arousal caused most frequently an increase of highest mean arterial blood pressure in patients and controls. A useful definition for autonomic arousal for OSA and controls based on blood pressure and heart rate analysis was developed.
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Affiliation(s)
- Wibke Bartels
- Interdisciplinary Center of Sleep Medicine, Department of Cardiology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany
| | - Dana Buck
- Interdisciplinary Center of Sleep Medicine, Department of Cardiology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany; Department of Oto-Rhino-Laryngology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany
| | - Martin Glos
- Interdisciplinary Center of Sleep Medicine, Department of Cardiology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany
| | - Ingo Fietze
- Interdisciplinary Center of Sleep Medicine, Department of Cardiology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany
| | - Thomas Penzel
- Interdisciplinary Center of Sleep Medicine, Department of Cardiology, Charité Universitätsmedizin Berlin, Charité Campus Mitte, Charitéplatz 1, Berlin 10117, Germany.
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Tremblay JC, Boulet LM, Tymko MM, Foster GE. Intermittent hypoxia and arterial blood pressure control in humans: role of the peripheral vasculature and carotid baroreflex. Am J Physiol Heart Circ Physiol 2016; 311:H699-706. [PMID: 27402667 DOI: 10.1152/ajpheart.00388.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/06/2016] [Indexed: 11/22/2022]
Abstract
Intermittent hypoxia (IH) occurs in association with obstructive sleep apnea and likely contributes to the pathogenesis of hypertension. The purpose of this study was to examine the putative early adaptations at the level of the peripheral vasculature and carotid baroreflex (CBR) that may promote the development of hypertension. Ten healthy male participants (26 ± 1 yr, BMI = 24 ± 1 kg/m(2)) were exposed to 6 h of IH (1-min cycles of normoxia and hypoxia) and SHAM in a single-blinded, counterbalanced crossover study design. Ambulatory blood pressure was measured during each condition and the following night. Vascular strain of the carotid and femoral artery, a measure of localized arterial stiffness, and hemodynamic shear patterns in the brachial and femoral arteries were measured during each condition. Brachial artery reactive hyperemia flow-mediated vasodilation was assessed before and after each condition as a measure of endothelial function. CBR function and its control over leg vascular conductance (LVC) were measured after each condition with a variable-pressure neck chamber. Intermittent hypoxia 1) increased nighttime pulse pressure by 3.2 ± 1.3 mmHg, 2) altered femoral but not brachial artery hemodynamics, 3) did not affect brachial artery endothelial function, 4) reduced vascular strain in the carotid and possibly femoral artery, and 5) shifted CBR mean arterial pressure (MAP) to higher MAP while blunting LVC responses to CBR loading. These results suggest limb-specific vascular impairments, reduced vascular strain, and CBR resetting combined with blunted LVC responses are factors in the early pathogenesis of IH-induced development of hypertension.
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Affiliation(s)
- Joshua C Tremblay
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Michael M Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
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Mozer MT, Holbein WW, Joyner MJ, Curry TB, Limberg JK. Reductions in carotid chemoreceptor activity with low-dose dopamine improves baroreflex control of heart rate during hypoxia in humans. Physiol Rep 2016; 4:e12859. [PMID: 27418545 PMCID: PMC4945841 DOI: 10.14814/phy2.12859] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/13/2016] [Accepted: 06/18/2016] [Indexed: 11/24/2022] Open
Abstract
The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of heart rate with exposure to hypoxia. We hypothesized spontaneous cardiac baroreflex sensitivity (scBRS) would be reduced with hypoxia and this effect would be blunted when carotid chemoreceptor activity was reduced with low-dose dopamine. Fifteen healthy adults (11 M/4 F) completed two visits randomized to intravenous dopamine or placebo (saline). On each visit, subjects were exposed to 5-min normoxia (~99% SpO2), followed by 5-min hypoxia (~84% SpO2). Blood pressure (intra-arterial catheter) and heart rate (ECG) were measured continuously and scBRS was assessed by spectrum and sequence methodologies. scBRS was reduced with hypoxia (P < 0.01). Using the spectrum analysis approach, the fall in scBRS with hypoxia was attenuated with infusion of low-dose dopamine (P < 0.01). The decrease in baroreflex sensitivity to rising pressures (scBRS "up-up") was also attenuated with low-dose dopamine (P < 0.05). However, dopamine did not attenuate the decrease in baroreflex sensitivity to falling pressures (scBRS "down-down"; P > 0.05). Present findings are consistent with a reduction in scBRS with systemic hypoxia. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when activity of the chemoreceptors is reduced with low-dose dopamine. However, the improvement in scBRS with dopamine appears to be specific to rising blood pressures. These results may have important implications for impairments in baroreflex function common in disease states of acute and/or chronic hypoxemia, as well as the experimental use of dopamine to assess such changes.
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Affiliation(s)
- Michael T Mozer
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| | | | | | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
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Hamaoka T, Murai H, Kaneko S, Usui S, Okabe Y, Tokuhisa H, Kato T, Furusho H, Sugiyama Y, Nakatsumi Y, Takata S, Takamura M. Single-Unit Muscle Sympathetic Nerve Activity Reflects Sleep Apnea Severity, Especially in Severe Obstructive Sleep Apnea Patients. Front Physiol 2016; 7:66. [PMID: 26973534 PMCID: PMC4773439 DOI: 10.3389/fphys.2016.00066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/12/2016] [Indexed: 01/19/2023] Open
Abstract
Obstructive sleep apnea syndrome (OSAS) is associated with augmented sympathetic nerve activity, as assessed by multi-unit muscle sympathetic nerve activity (MSNA). However, it is still unclear whether single-unit MSNA is a better reflection of sleep apnea severity according to the apnea-hypopnea index (AHI). One hundred and two OSAS patients underwent full polysomnography and single- and multi-unit MSNA measurements. Univariate and multivariate regression analysis were performed to determine which parameters correlated with OSAS severity, which was defined by the AHI. Single- and multi-unit MSNA were significantly and positively correlated with AHI severity. The AHI was also significantly correlated with multi-unit MSNA burst frequency (r = 0.437, p < 0.0001) and single-unit MSNA spike frequency (r = 0.632, p < 0.0001). Multivariable analysis revealed that SF was correlated most significantly with AHI (T = 7.27, p < 0.0001). The distributions of multiple single-unit spikes per one cardiac interval did not differ between patients with an AHI of <30 and those with and AHI of 30–55 events/h; however, the pattern of each multiple spike firing were significantly higher in patients with an AHI of >55. These results suggest that sympathetic nerve activity is associated with sleep apnea severity. In addition, single-unit MSNA is a more accurate reflection of sleep apnea severity with alternation of the firing pattern, especially in patients with very severe OSAS.
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Affiliation(s)
- Takuto Hamaoka
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Hisayoshi Murai
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Shuichi Kaneko
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Soichiro Usui
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Yoshitaka Okabe
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Hideki Tokuhisa
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Takeshi Kato
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | - Hiroshi Furusho
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
| | | | | | | | - Masayuki Takamura
- Department of Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University Kanazawa, Japan
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Rao AD, Bonyhay I, Dankwa J, Baimas-George M, Kneen L, Ballatori S, Freeman R, Adler GK. Baroreflex Sensitivity Impairment During Hypoglycemia: Implications for Cardiovascular Control. Diabetes 2016; 65:209-15. [PMID: 26438610 PMCID: PMC4686952 DOI: 10.2337/db15-0871] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/28/2015] [Indexed: 11/13/2022]
Abstract
Studies have shown associations between exposure to hypoglycemia and increased mortality, raising the possibility that hypoglycemia has adverse cardiovascular effects. In this study, we determined the acute effects of hypoglycemia on cardiovascular autonomic control. Seventeen healthy volunteers were exposed to experimental hypoglycemia (2.8 mmol/L) for 120 min. Cardiac vagal baroreflex function was assessed using the modified Oxford method before the initiation of the hypoglycemic-hyperinsulinemic clamp protocol and during the last 30 min of hypoglycemia. During hypoglycemia, compared with baseline euglycemic conditions, 1) baroreflex sensitivity decreases significantly (19.2 ± 7.5 vs. 32.9 ± 16.6 ms/mmHg, P < 0.005), 2) the systolic blood pressure threshold for baroreflex activation increases significantly (the baroreflex function shifts to the right; 120 ± 14 vs. 112 ± 12 mmHg, P < 0.005), and 3) the maximum R-R interval response (1,088 ± 132 vs. 1,496 ± 194 ms, P < 0.001) and maximal range of the R-R interval response (414 ± 128 vs. 817 ± 183 ms, P < 0.001) decrease significantly. These findings indicate reduced vagal control and impaired cardiovascular homeostasis during hypoglycemia.
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Affiliation(s)
- Ajay D Rao
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, Temple University School of Medicine, Philadelphia, PA
| | - Istvan Bonyhay
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Joel Dankwa
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Maria Baimas-George
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Lindsay Kneen
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Sarah Ballatori
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Roy Freeman
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Gail K Adler
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
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Chronic intermittent hypoxia induces changes in expression of synaptic proteins in the nucleus of the solitary tract. Brain Res 2015; 1622:300-7. [DOI: 10.1016/j.brainres.2015.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 06/27/2015] [Accepted: 07/02/2015] [Indexed: 01/26/2023]
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Limberg JK, Dube S, Kuijpers M, Farni KE, Basu A, Rizza RA, Curry TB, Basu R, Joyner MJ. Effect of hypoxia on heart rate variability and baroreflex sensitivity during hypoglycemia in type 1 diabetes mellitus. Clin Auton Res 2015; 25:243-50. [PMID: 26141615 PMCID: PMC4569520 DOI: 10.1007/s10286-015-0301-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/12/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE Patients with type 1 diabetes mellitus exhibit impairments in autonomic and cardiovascular control which are worsened with acute hypoglycemia--thus increasing the risk of adverse cardiovascular events. Hypoxia, as seen with the common comorbidity of sleep apnea, may lead to further autonomic dysfunction and an increased risk of ventricular arrhythmias. Therefore, we hypothesized that heart rate variability (HRV) and baroreflex sensitivity (BRS) would be reduced during hypoglycemia in adults with type 1 diabetes, with a further decline when combined with hypoxia. METHODS Subjects with type 1 diabetes (n = 13; HbA1c = 7.5 ± 0.3 %, duration of diabetes = 17 ± 5 yrs) completed two 180 min hyperinsulinemic (2 mU/kg TBW/min), hypoglycemic (~3.3 µmol/mL) clamps separated by a minimum of 1 week and randomized to normoxia (SpO2 ~98 %) or hypoxia (SpO2 ~85 %). Heart rate (electrocardiogram) and blood pressure (finger photoplethysmography) were analyzed at baseline and during the hypoglycemic clamp for measures of HRV and spontaneous cardiac BRS (sCBRS). RESULTS Hypoglycemia resulted in significant reductions in HRV and sCBRS when compared with baseline levels (main effect of hypoglycemia: p < 0.05). HRV and sCBRS were further impaired during hypoxia (main effect of hypoxia: p < 0.05). CONCLUSIONS Acute hypoxia worsens hypoglycemia-mediated impairments in autonomic and cardiovascular control in patients with type 1 diabetes and may increase the risk of cardiovascular mortality. These results highlight the potential cumulative dangers of hypoglycemia and hypoxia in this vulnerable population.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Anesthesiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55901, USA.
| | - Simmi Dube
- Department of Endocrinology, Mayo Clinic, Rochester, MN, USA
| | - Myrthe Kuijpers
- Department of Anesthesiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55901, USA
| | - Kathryn E Farni
- Department of Anesthesiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55901, USA
| | - Ananda Basu
- Department of Endocrinology, Mayo Clinic, Rochester, MN, USA
| | - Robert A Rizza
- Department of Endocrinology, Mayo Clinic, Rochester, MN, USA
| | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55901, USA
| | - Rita Basu
- Department of Endocrinology, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, 200 1st St SW, Rochester, MN, 55901, USA
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Bruce RM, White MJ. The ventilatory response to muscle afferent activation during concurrent hypercapnia in humans: central and peripheral mechanisms. Exp Physiol 2015; 100:896-904. [DOI: 10.1113/ep085024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 05/14/2015] [Indexed: 01/25/2023]
Affiliation(s)
- Richard M. Bruce
- School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; UK
| | - Michael J. White
- School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; UK
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Huang CC, Lin WC, Chen HL, Friedman M, Lin MC, Lin HC, Lu CH. Improvement of baroreflex sensitivity in patients with obstructive sleep apnea following surgical treatment. Clin Neurophysiol 2015; 127:544-550. [PMID: 26116297 DOI: 10.1016/j.clinph.2015.05.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/05/2015] [Accepted: 05/16/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Depressed baroreflex sensitivity (BRS) have been reported in patients with obstructive sleep apnea (OSA). This study aimed to determine if surgery can improve the clinical outcomes by investigating changes in BRS and in other cardiovascular autonomic parameters. METHODS Eighty-one OSA patients were enrolled. They were classified as mild OSA if their apnea-hypopnea index (AHI) was 5-15, moderate OSA if their AHI was 15-30, and sever OSA if their AHI was >30. Twenty-three subjects with AHI<5 were recruited as controls. For patients who received surgery, polysomnography (PSG) and autonomic tests were evaluated upon enrollment and six-months after surgery. RESULTS The patient number for mild, moderate, and severe OSA was 22, 22, and 37, respectively. BRS on enrollment showed significant difference among the four groups, with the highest BRS in the control group, follow by the mild, moderate, and severe OSA groups. There were significant correlations between BRS and all PSG parameters. The depressed BRS significantly improved after surgery. CONCLUSIONS Surgical modifications of the upper airways can improve the depressed BRS in OSA patients. SIGNIFICANCE The study offers the promise that surgical treatment for OSA not only improves the index of PSG, but also reduces the possibility of cardiovascular risk.
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Affiliation(s)
- Chih-Cheng Huang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Wei-Che Lin
- Department of Radiology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Hsiu-Ling Chen
- Department of Radiology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Michael Friedman
- Department of Otolaryngology and Bronchoesophagology, Rush University Medical Center, Chicago, IL, USA; Department of Otolaryngology, Advocate Illinois Masonic Medical Center, Chicago, IL, USA
| | - Meng-Chih Lin
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Sleep Center, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Hsin-Ching Lin
- Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Sleep Center, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
| | - Cheng-Hsien Lu
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Biological Science, National Sun Yat-Sen University, Kaohsiung, Taiwan; Department of Neurology, Xiamen Chang Gung Memorial Hospital, Xiamen, Fujian, China.
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Ataee P, Hahn JO, Dumont GA, Noubari HA, Boyce WT. A model-based approach to stability analysis of autonomic-cardiac regulation. Comput Biol Med 2015; 61:119-26. [PMID: 25898226 DOI: 10.1016/j.compbiomed.2015.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/23/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022]
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Limberg JK, Taylor JL, Mozer MT, Dube S, Basu A, Basu R, Rizza RA, Curry TB, Joyner MJ, Wehrwein EA. Effect of bilateral carotid body resection on cardiac baroreflex control of blood pressure during hypoglycemia. Hypertension 2015; 65:1365-71. [PMID: 25870188 DOI: 10.1161/hypertensionaha.115.05325] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 03/23/2015] [Indexed: 01/19/2023]
Abstract
Hypoglycemia results in a reduction in cardiac baroreflex sensitivity and a shift in the baroreflex working range to higher heart rates. This effect is mediated, in part, by the carotid chemoreceptors. Therefore, we hypothesized hypoglycemia-mediated changes in baroreflex control of heart rate would be blunted in carotid body-resected patients when compared with healthy controls. Five patients with bilateral carotid body resection for glomus tumors and 10 healthy controls completed a 180-minute hyperinsulinemic, hypoglycemic (≈3.3 mmol/L) clamp. Changes in heart rate, blood pressure, and spontaneous cardiac baroreflex sensitivity were assessed. Baseline baroreflex sensitivity was not different between groups (P>0.05). Hypoglycemia resulted in a reduction in baroreflex sensitivity in both the groups (main effect of time, P<0.01) and responses were lower in resected patients when compared with controls (main effect of group, P<0.05). Hypoglycemia resulted in large reductions in systolic (-17±7 mm Hg) and mean (-14±5 mm Hg) blood pressure in resected patients that were not observed in controls (interaction of group and time, P<0.05). Despite lower blood pressures, increases in heart rate with hypoglycemia were blunted in resected patients (interaction of group and time, P<0.01). Major novel findings from this study demonstrate that intact carotid chemoreceptors are essential for increasing heart rate and maintaining arterial blood pressure during hypoglycemia in humans. These data support a contribution of the carotid chemoreceptors to blood pressure control and highlight the potential widespread effects of carotid body resection in humans.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Jennifer L Taylor
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Michael T Mozer
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Simmi Dube
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Ananda Basu
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Rita Basu
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Robert A Rizza
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Timothy B Curry
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
| | - Michael J Joyner
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN.
| | - Erica A Wehrwein
- Department of Physiology, Michigan State University, East Lansing (E.A.W.); Departments of Anesthesiology (J.K.L., J.L.T., M.T.M., T.B.C., M.J.J.), and Endocrinology (S.D., A.B., R.B., R.A.R.), Mayo Clinic, Rochester, MN
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Liu N, Lory C, Assenzo V, Cocard V, Chazot T, Le Guen M, Sessler D, Journois D, Fischler M. Feasibility of closed-loop co-administration of propofol and remifentanil guided by the bispectral index in obese patients: a prospective cohort comparison †. Br J Anaesth 2015; 114:605-14. [DOI: 10.1093/bja/aeu401] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Lyons OD, Ryan CM. Sleep Apnea and Stroke. Can J Cardiol 2015; 31:918-27. [PMID: 26112302 DOI: 10.1016/j.cjca.2015.03.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/27/2015] [Accepted: 03/01/2015] [Indexed: 12/19/2022] Open
Abstract
Stroke is the second leading cause of death worldwide and often has devastating consequences for affected individuals in terms of chronic disability. Traditional risk factors such as age, male sex, ethnicity, hypertension, and atrial fibrillation explain 60%-80% of the risk of stroke. Obstructive sleep apnea (OSA) is highly prevalent in individuals who have had a stroke and its emerging role as a potential modifiable risk factor for stroke has been recognized in the most recent American Heart Association stroke guidelines, which recommend consideration of screening for and treatment of OSA in this regard. In this article we provide an overview of the current evidence-based knowledge related to stroke and sleep apnea. The main focus of this article is key pathophysiological mechanisms by which OSA might increase the risk for stroke. The effect of OSA on stroke outcomes and the efficacy of treatment of OSA on these outcomes is also discussed.
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Affiliation(s)
- Owen D Lyons
- Centre for Sleep Health and Research, University of Toronto/Toronto General Hospital and Toronto Rehabilitation Institute, Toronto, Ontario, Canada
| | - Clodagh M Ryan
- Centre for Sleep Health and Research, University of Toronto/Toronto General Hospital and Toronto Rehabilitation Institute, Toronto, Ontario, Canada.
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Diogo LN, Monteiro EC. The efficacy of antihypertensive drugs in chronic intermittent hypoxia conditions. Front Physiol 2014; 5:361. [PMID: 25295010 PMCID: PMC4170135 DOI: 10.3389/fphys.2014.00361] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 09/03/2014] [Indexed: 12/22/2022] Open
Abstract
Sleep apnea/hypopnea disorders include centrally originated diseases and obstructive sleep apnea (OSA). This last condition is renowned as a frequent secondary cause of hypertension (HT). The mechanisms involved in the pathogenesis of HT can be summarized in relation to two main pathways: sympathetic nervous system stimulation mediated mainly by activation of carotid body (CB) chemoreflexes and/or asphyxia, and, by no means the least important, the systemic effects of chronic intermittent hypoxia (CIH). The use of animal models has revealed that CIH is the critical stimulus underlying sympathetic activity and hypertension, and that this effect requires the presence of functional arterial chemoreceptors, which are hyperactive in CIH. These models of CIH mimic the HT observed in humans and allow the study of CIH independently without the mechanical obstruction component. The effect of continuous positive airway pressure (CPAP), the gold standard treatment for OSA patients, to reduce blood pressure seems to be modest and concomitant antihypertensive therapy is still required. We focus this review on the efficacy of pharmacological interventions to revert HT associated with CIH conditions in both animal models and humans. First, we explore the experimental animal models, developed to mimic HT related to CIH, which have been used to investigate the effect of antihypertensive drugs (AHDs). Second, we review what is known about drug efficacy to reverse HT induced by CIH in animals. Moreover, findings in humans with OSA are cited to demonstrate the lack of strong evidence for the establishment of a first-line antihypertensive regimen for these patients. Indeed, specific therapeutic guidelines for the pharmacological treatment of HT in these patients are still lacking. Finally, we discuss the future perspectives concerning the non-pharmacological and pharmacological management of this particular type of HT.
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Affiliation(s)
- Lucilia N Diogo
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Emília C Monteiro
- Centro de Estudos de Doenças Crónicas, CEDOC, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
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Divers revisited: The ventilatory response to carbon dioxide in experienced scuba divers. Respir Med 2014; 108:758-65. [DOI: 10.1016/j.rmed.2014.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 11/18/2022]
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Abstract
In this review we focus on the role of orexin in cardio-respiratory functions and its potential link to hypertension. (1) Orexin, cardiovascular function, and hypertension. In normal rats, central administration of orexin can induce significant increases in arterial blood pressure (ABP) and sympathetic nerve activity (SNA), which can be blocked by orexin receptor antagonists. In spontaneously hypertensive rats (SHRs), antagonizing orexin receptors can significantly lower blood pressure under anesthetized or conscious conditions. (2) Orexin, respiratory function, and central chemoreception. The prepro-orexin knockout mouse has a significantly attenuated ventilatory CO2 chemoreflex, and in normal rats, central application of orexin stimulates breathing while blocking orexin receptors decreases the ventilatory CO2 chemoreflex. Interestingly, SHRs have a significantly increased ventilatory CO2 chemoreflex relative to normotensive WKY rats and blocking both orexin receptors can normalize this exaggerated response. (3) Orexin, central chemoreception, and hypertension. SHRs have higher ABP and SNA along with an enhanced ventilatory CO2 chemoreflex. Treating SHRs by blocking both orexin receptors with oral administration of an antagonist, almorexant (Almxt), can normalize the CO2 chemoreflex and significantly lower ABP and SNA. We interpret these results to suggest that the orexin system participates in the pathogenesis and maintenance of high blood pressure in SHRs, and the central chemoreflex may be a causal link to the increased SNA and ABP in SHRs. Modulation of the orexin system could be a potential target in treating some forms of hypertension.
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Affiliation(s)
- Aihua Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Eugene Nattie
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
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