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Guluzade NA, Huggard JD, Duffin J, Keir DA. A test of the interaction between central and peripheral respiratory chemoreflexes in humans. J Physiol 2023; 601:4591-4609. [PMID: 37566804 DOI: 10.1113/jp284772] [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: 03/30/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic CO2 tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Twenty participants (10F) completed three repetitions of modified rebreathing tests with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) clamped at 150, 70, 60 and 45 mmHg. End-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ),P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , ventilation (V ̇ $\dot{V}$ E ) and calculated oxygen saturation (SC O2 ) were measured breath-by-breath by gas-analyser and pneumotach. TheV ̇ $\dot{V}$ E -P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship of repeat-trials were linear-interpolated, combined, averaged into 1 mmHg bins, and fitted with a double-linear function (V ̇ $\dot{V}$ E S, L min-1 mmHg-1 ). PChS was computed at intervals of 1 mmHg ofP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding SC O2 ; and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). These processing steps were repeated at eachP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ to produce the PChS vs. isocapnicP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship. These were fitted with linear and polynomial functions, and Akaike information criterion identified the best-fit model. One-way repeated measures analysis of variance assessed between-condition differences.V ̇ $\dot{V}$ E S increased (P < 0.0001) with isoxicP ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ from 3.7 ± 1.5 L min-1 mmHg-1 at 150 mmHg to 4.4 ± 1.8, 5.0 ± 1.6 and 6.0 ± 2.2 Lmin-1 mmHg-1 at 70, 60 and 45 mmHg, respectively. Mean SC O2 fell progressively (99.3 ± 0%, 93.7 ± 0.1%, 90.4 ± 0.1% and 80.5 ± 0.1%; P < 0.0001). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear model in 75%. Despite increasing central chemoreflex activation, PChS increased linearly withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ indicative of an additive central-peripheral chemoreflex response. KEY POINTS: How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Participants performed three repetitions of modified rebreathing with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fixed at 150, 70, 60 and 45 mmHg. PChS was computed at intervals of 1 mmHg of end-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding calculated oxygen saturation (SC O2 ); and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear (rather than polynomial) model in 15 of 20. Most participants did not exhibit a hypo- or hyper-additive effect of central chemoreceptors on the peripheral chemoreflex indicating that the interaction was additive.
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Affiliation(s)
- Nasimi A Guluzade
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Joshua D Huggard
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
| | - Daniel A Keir
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, ON, Canada
- Lawson Health Research Institute, London, ON, Canada
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Duan D, Perin J, Osman A, Sgambati F, Kim LJ, Pham LV, Polotsky VY, Jun JC. Effects of sex, age, and body mass index on serum bicarbonate. FRONTIERS IN SLEEP 2023; 2:1195823. [PMID: 37736141 PMCID: PMC10512520 DOI: 10.3389/frsle.2023.1195823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
Rationale Obesity hypoventilation syndrome (OHS) is often underdiagnosed, with significant morbidity and mortality. Bicarbonate, as a surrogate of arterial carbon dioxide, has been proposed as a screening tool for OHS. Understanding the predictors of serum bicarbonate could provide insights into risk factors for OHS. We hypothesized that the bicarbonate levels would increase with an increase in body mass index (BMI), since the prevalence of OHS increases with obesity. Methods We used the TriNetX Research Network, an electronic health record database with de-identified clinical data from participating healthcare organizations across the United States, to identify 93,320 adults without pulmonary or advanced renal diseases who had serum bicarbonate and BMI measurements within 6 months of each other between 2017 and 2022. We used linear regression analysis to examine the associations between bicarbonate and BMI, age, and their interactions for the entire cohort and stratified by sex. We also applied a non-linear machine learning algorithm (XGBoost) to examine the relative importance of age, BMI, sex, race/ethnicity, and obstructive sleep apnea (OSA) status on bicarbonate. Results This cohort population was 56% women and 72% white and 80% non-Hispanic individuals, with an average (SD) age of 49.4 (17.9) years and a BMI of 29.1 (6.1) kg/m2. The mean bicarbonate was 24.8 (2.8) mmol/L, with higher levels in men (mean 25.2 mmol/L) than in women (mean 24.4 mmol/L). We found a small negative association between bicarbonate and BMI, with an expected change of -0.03 mmol/L in bicarbonate for each 1 kg/m2 increase in BMI (p < 0.001), in the entire cohort and both sexes. We found sex differences in the bicarbonate trajectory with age, with women exhibiting lower bicarbonate values than men until age 50, after which the bicarbonate levels were modestly higher. The non-linear machine learning algorithm similarly revealed that age and sex played larger roles in determining bicarbonate levels than the BMI or OSA status. Conclusion Contrary to our hypothesis, BMI is not associated with elevated bicarbonate levels, and age modifies the impact of sex on bicarbonate.
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Affiliation(s)
- Daisy Duan
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jamie Perin
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Adam Osman
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Francis Sgambati
- Center for Interdisciplinary Sleep Research and Education, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Lenise J. Kim
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Luu V. Pham
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Vsevolod Y. Polotsky
- Departments of Anesthesiology and Critical Care Medicine and Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Jonathan C. Jun
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Sacramento JF, Caires I, Guarino MP, Ribeiro MJ, Santiago JCP, Timóteo AT, Selas M, Mota-Carmo M, Conde SV. Increased Abdominal Perimeter Differently Affects Respiratory Function in Men and Women. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1427:135-141. [PMID: 37322344 DOI: 10.1007/978-3-031-32371-3_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Obesity is a worldwide epidemic being the main cause of cardiovascular, metabolic disturbances and chronic pulmonary diseases. The increase in body weight may affect the respiratory system due to fat deposition and systemic inflammation. Herein, we evaluated the sex differences in the impact of obesity and high abdominal circumference on basal ventilation. Thirty-five subjects, 23 women and 12 men with a median age of 61 and 67, respectively, were studied and classified as overweight and obese according to body mass index (BMI) and were also divided by the abdominal circumference. Basal ventilation, namely, respiratory frequency, tidal volume, and minute ventilation, was evaluated. In normal and overweight women, basal ventilation did not change, but obese women exhibited a decrease in tidal volume. In men, overweight and obese subjects did not exhibit altered basal ventilation. In contrast, when subjects were subdivided based on the abdominal perimeter, a higher circumference did not change the respiratory frequency but induced a decrease in tidal volume and minute ventilation in women, while in men these two parameters increased. In conclusion, higher abdominal circumference rather than BMI is associated with alterations in basal ventilation in women and men.
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Affiliation(s)
- Joana F Sacramento
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Iolanda Caires
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Maria P Guarino
- ciTechCare, Escola Superior de Saúde de Leiria, Instituto Politécnico de Leiria, Leiria, Portugal
| | - Maria J Ribeiro
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
| | - João C P Santiago
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Ana T Timóteo
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
- Serviço de Cardiologia, Hospital Santa Marta, Centro Hospital Lisboa Central, EPE, Lisbon, Portugal
| | - Mafalda Selas
- Serviço de Cardiologia, Hospital Santa Marta, Centro Hospital Lisboa Central, EPE, Lisbon, Portugal
| | - Miguel Mota-Carmo
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal
- Serviço de Cardiologia, Hospital Santa Marta, Centro Hospital Lisboa Central, EPE, Lisbon, Portugal
| | - Silvia V Conde
- iNOVA4Health, NOVA Medical School|Faculdade de Ciências Médicas, NMS|FCM, Universidade Nova de Lisboa, Lisbon, Portugal.
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de la Rosa T, Calvo VS, Gonçalves VC, Ferreira CB, Cabral LM, Souza FDC, Scerni DA, Scorza FA, Moreira TS, Takakura AC. Respiratory deficits in a female rat model of Parkinson's Disease. Exp Physiol 2022; 107:1349-1359. [PMID: 36030407 DOI: 10.1113/ep090378] [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: 02/14/2022] [Accepted: 08/23/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does 6-OHDA-induced Parkinson's Disease model affect the respiratory response in female rats? What effect does ovariectomy have on that response? What is the main finding and its importance? Our results suggest a protective effect of ovarian hormones in maintaining normal neuroanatomical integrity of the medullary respiratory nucleus in females. It was observed that ovariectomy alone reduced NK1r density in preBotc and BotC, and there was an incremental effect of 6-OHDA and ovariectomy on RTN neurons. ABSTRACT Emerging evidence indicates that Parkinson's disease (PD) courses with autonomic and respiratory deficiencies in addition to the classical motor symptoms. The prevalence of PD is lower in women, and it has been hypothesized that neuroprotection by ovarian hormones can explain this difference. While male PD animal models present changes in the central respiratory control areas, as well as ventilatory parameters under normoxia and hypercapnia, little is known about sex differences regarding respiratory deficits in this disease background. This study aimed to explore the neuroanatomical and functional respiratory changes in intact and ovariectomized female rats subjected to chemically induced PD via a bilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA). The respiratory parameters were evaluated by whole-body plethysmography, and the neuroanatomy was monitored using immunohistochemistry. It was found that dopaminergic neurons in the substantia nigra and neurokinin-1 receptor (NK1r) density in the rostral ventrolateral respiratory group, Botzinger and pre-Botzinger complex were reduced in the chemically induced PD animals. Additionally, reduced numbers of Phox2b neurons were only observed in the retrotrapezoid nucleus of PD-ovariectomized rats. Concerning respiratory parameters, in ovariectomized rats, the resting and hypercapnia-induced tidal volume (VT ) is reduced, and ventilation (VE ) changes independently of 6-OHDA administration. Notably, there is a reduction in the number of RTN phox2b neurons and hypercapnia-induced respiratory changes in PD-ovariectomized animals due to a 6-OHDA and OVX interaction. These results suggest a protective effect induced by ovarian hormones in neuroanatomical changes observed in a female experimental PD model. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Tomás de la Rosa
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil.,Neuropsychopharmacology and Psychobiology Research Group, Department of Psychology, University of Cádiz, Cádiz, Spain.,Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
| | - Viviam S Calvo
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Valeria C Gonçalves
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Caroline B Ferreira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Lais M Cabral
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Felipe da C Souza
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Débora A Scerni
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Fúlvio A Scorza
- Neurology Department, Escola Paulista de Medicina Universidade Federal de São Paulo, São Paulo, Brazil
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, São Paulo, Brazil
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Hussien NI, El-Kerdasy HI, Sorour SM, Shoman AA. Chronic oestrogen deficiency induced by ovariectomy may cause lung fibrosis through activation of the renin-angiotensin system in rats. Arch Physiol Biochem 2022; 128:290-299. [PMID: 31608713 DOI: 10.1080/13813455.2019.1676262] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
CONTEXT Oestrogen deficiency is linked with pulmonary fibrosis. Additionally, it may lead to over-activation of the renin-angiotensin system (RAS), which worsens lung fibrosis. OBJECTIVE The present study aims to investigate the role of RAS on lung fibrosis associated with oestrogen deficiency in ovariectomised rats. MATERIALS AND METHODS Serum 17β-oestradiol (E2), arterial blood gases, plasma angiotensin II levels, lung tissue hydroxyproline content, and transforming growth factor beta 1 (TGF-β1) concentration, the mRNA expression of angiotensin type 1 receptor (AT1R), and angiotensin-converting enzyme (ACE1) were evaluated. Moreover, lung tissues were examined by histopathology and immunohistochemistry. RESULTS Hydroxyproline content, TGF-β1 concentration, plasma angiotensin II, the relative mRNA expression of ACE1, and AT1R is found to increase in ovariectomised rats. The mentioned changes can be largely rescued by administration of RAS blockers. CONCLUSION Oestrogen deficiency activates RAS, which consequently increases the expression of pro-fibrotic factors and stimulates the fibrotic cascade causing lung fibrosis.
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Affiliation(s)
- Noha I Hussien
- Department of Physiology, Faculty of Medicine, Benha University, Benha, Egypt
| | - Hanan I El-Kerdasy
- Department of Anatomy, Faculty of Medicine, Benha University, Benha, Egypt
| | - Safwa M Sorour
- Department of Clinical Pharmacology, Faculty of Medicine, Benha University, Benha, Egypt
| | - Abeer A Shoman
- Department of Physiology, Faculty of Medicine, Benha University, Benha, Egypt
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Zhang W, Gao X. A Cone Beam CT Study of Upper Airway Morphology in Perimenopausal and Postmenopausal Women. Int J Womens Health 2021; 13:1129-1137. [PMID: 34853538 PMCID: PMC8627894 DOI: 10.2147/ijwh.s335728] [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: 08/24/2021] [Accepted: 11/11/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose Menopause is accompanied by a decline in estrogen and progesterone. Several studies have demonstrated that upper airway patency decreases in women after menopause, while morphology changes are still a lack of evidence. This study aimed to explore upper airway morphology changes in perimenopausal and postmenopausal women. Methods This retrospective cross-sectional study included 367 consecutive Chinese female patients over 25 years old who had routinely taken large-field cone beam computed tomography in the imaging library of Peking University School and Hospital of Stomatology from October 2016 to September 2020. A total of 283 males were screened as sex controls according to the same age group. Upper airway morphology, hyoid position and facial pattern were measured. The association between perimenopausal and postmenopausal years and upper airway morphology in both sexes was analyzed. Results Perimenopausal women (aged 45-54 years) showed a significant decrease in the volume (3172.91mm3, 95% CI = 653.86-5691.96) and minimum cross-sectional area (37.08 mm2, 95% CI = 5.36-68.80), and a significant increase in the length (-1.96mm, 95% CI = -3.62 to -0.29) of upper airway compared to adjacent reproductive years (aged 35-44), while this difference was neither seen in other adjacent two reproductive age groups of females nor in the same age groups of males. In postmenopausal women (55 years and older), hyoid position was significantly lower (-2.74mm, 95% CI = -4.42 to -1.07) than either age group, while no similar changes were seen in men. Conclusion Women had smaller airway volume, reduced upper airway cross-sectional area and longer airway length in perimenopausal years, and a significantly lower hyoid position in postmenopausal years. These changes may be related to menopause itself and independent of the changes associated with aging.
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Affiliation(s)
- Wanxin Zhang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, People's Republic of China
| | - Xuemei Gao
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, People's Republic of China
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Kinkead R, Gagnon M, Joseph V, Sériès F, Ambrozio-Marques D. Stress and Loss of Ovarian Function: Novel Insights into the Origins of Sex-Based Differences in the Manifestations of Respiratory Control Disorders During Sleep. Clin Chest Med 2021; 42:391-405. [PMID: 34353446 DOI: 10.1016/j.ccm.2021.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The respiratory system of women and men develops and functions in distinct neuroendocrine milieus. Despite differences in anatomy and neural control, homeostasis of arterial blood gases is ensured in healthy individuals regardless of sex. This convergence in function differs from the sex-based differences observed in many respiratory diseases. Sleep-disordered breathing (SDB) results mainly from episodes of upper airway closure. This complex and multifactorial respiratory disorder shows significant sexual dimorphism in its clinical manifestations and comorbidities. Guided by recent progress from basic research, this review discusses the hypothesis that stress is necessary to reveal the sexual dimorphism of SDB.
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Affiliation(s)
- Richard Kinkead
- Department of Pediatrics, Université Laval, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, 2725 Chemin Ste-Foy, Québec, Québec G1V 4G5, Canada.
| | - Marianne Gagnon
- Department of Pediatrics, Université Laval, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, 2725 Chemin Ste-Foy, Québec, Québec G1V 4G5, Canada
| | - Vincent Joseph
- Department of Pediatrics, Université Laval, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, 2725 Chemin Ste-Foy, Québec, Québec G1V 4G5, Canada
| | - Frédéric Sériès
- Department of Medicine, Université Laval, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Québec, Québec, Canada
| | - Danuzia Ambrozio-Marques
- Department of Pediatrics, Université Laval, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, 2725 Chemin Ste-Foy, Québec, Québec G1V 4G5, Canada
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Tenorio-Lopes L, Kinkead R. Sex-Specific Effects of Stress on Respiratory Control: Plasticity, Adaptation, and Dysfunction. Compr Physiol 2021; 11:2097-2134. [PMID: 34107062 DOI: 10.1002/cphy.c200022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
As our understanding of respiratory control evolves, we appreciate how the basic neurobiological principles of plasticity discovered in other systems shape the development and function of the respiratory control system. While breathing is a robust homeostatic function, there is growing evidence that stress disrupts respiratory control in ways that predispose to disease. Neonatal stress (in the form of maternal separation) affects "classical" respiratory control structures such as the peripheral O2 sensors (carotid bodies) and the medulla (e.g., nucleus of the solitary tract). Furthermore, early life stress disrupts the paraventricular nucleus of the hypothalamus (PVH), a structure that has emerged as a primary determinant of the intensity of the ventilatory response to hypoxia. Although underestimated, the PVH's influence on respiratory function is a logical extension of the hypothalamic control of metabolic demand and supply. In this article, we review the functional and anatomical links between the stress neuroendocrine axis and the medullary network regulating breathing. We then present the persistent and sex-specific effects of neonatal stress on respiratory control in adult rats. The similarities between the respiratory phenotype of stressed rats and clinical manifestations of respiratory control disorders such as sleep-disordered breathing and panic attacks are remarkable. These observations are in line with the scientific consensus that the origins of adult disease are often found among developmental and biological disruptions occurring during early life. These observations bring a different perspective on the structural hierarchy of respiratory homeostasis and point to new directions in our understanding of the etiology of respiratory control disorders. © 2021 American Physiological Society. Compr Physiol 11:1-38, 2021.
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Affiliation(s)
- Luana Tenorio-Lopes
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Richard Kinkead
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
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Coupal KE, Heeney ND, Hockin BCD, Ronsley R, Armstrong K, Sanatani S, Claydon VE. Pubertal Hormonal Changes and the Autonomic Nervous System: Potential Role in Pediatric Orthostatic Intolerance. Front Neurosci 2019; 13:1197. [PMID: 31798399 PMCID: PMC6861527 DOI: 10.3389/fnins.2019.01197] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
Puberty is initiated by hormonal changes in the adolescent body that trigger physical and behavioral changes to reach adult maturation. As these changes occur, some adolescents experience concerning pubertal symptoms that are associated with dysfunction of the autonomic nervous system (ANS). Vasovagal syncope (VVS) and Postural Orthostatic Tachycardia Syndrome (POTS) are common disorders of the ANS associated with puberty that are related to orthostatic intolerance and share similar symptoms. Compared to young males, young females have decreased orthostatic tolerance and a higher incidence of VVS and POTS. As puberty is linked to changes in specific sex and non-sex hormones, and hormonal therapy sometimes improves orthostatic symptoms in female VVS patients, it is possible that pubertal hormones play a role in the increased susceptibility of young females to autonomic dysfunction. The purpose of this paper is to review the key hormonal changes associated with female puberty, their effects on the ANS, and their potential role in predisposing some adolescent females to cardiovascular autonomic dysfunctions such as VVS and POTS. Increases in pubertal hormones such as estrogen, thyroid hormones, growth hormone, insulin, and insulin-like growth factor-1 promote vasodilatation and decrease blood volume. This may be exacerbated by higher levels of progesterone, which suppresses catecholamine secretion and sympathetic outflow. Abnormal heart rate increases in POTS patients may be exacerbated by pubertal increases in leptin, insulin, and thyroid hormones acting to increase sympathetic nervous system activity and/or catecholamine levels. Given the coincidental timing of female pubertal hormone surges and adolescent onset of VVS and POTS in young women, coupled with the known roles of these hormones in modulating cardiovascular homeostasis, it is likely that female pubertal hormones play a role in predisposing females to VVS and POTS during puberty. Further research is necessary to confirm the effects of female pubertal hormones on autonomic function, and their role in pubertal autonomic disorders such as VVS and POTS, in order to inform the treatment and management of these debilitating disorders.
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Affiliation(s)
- Kassandra E Coupal
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Natalie D Heeney
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Brooke C D Hockin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Rebecca Ronsley
- Department of Pediatrics, BC Children's Hospital, Vancouver, BC, Canada
| | - Kathryn Armstrong
- Children's Heart Centre, BC Children's Hospital, Vancouver, BC, Canada
| | | | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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Sex differences in breathing. Comp Biochem Physiol A Mol Integr Physiol 2019; 238:110543. [PMID: 31445081 DOI: 10.1016/j.cbpa.2019.110543] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 01/15/2023]
Abstract
Breathing is a vital behavior that ensures both the adequate supply of oxygen and the elimination of CO2, and it is influenced by many factors. Despite that most of the studies in respiratory physiology rely heavily on male subjects, there is much evidence to suggest that sex is an important factor in the respiratory control system, including the susceptibility for some diseases. These different respiratory responses in males and females may be related to the actions of sex hormones, especially in adulthood. These hormones affect neuromodulatory systems that influence the central medullary rhythm/pontine pattern generator and integrator, sensory inputs to the integrator and motor output to the respiratory muscles. In this article, we will first review the sex dependence on the prevalence of some respiratory-related diseases. Then, we will discuss the role of sex and gonadal hormones in respiratory control under resting conditions and during respiratory challenges, such as hypoxia and hypercapnia, and whether hormonal fluctuations during the estrous/menstrual cycle affect breathing control. We will then discuss the role of the locus coeruleus, a sexually dimorphic CO2/pH-chemosensitive nucleus, on breathing regulation in males and females. Next, we will highlight the studies that exist regarding sex differences in respiratory control during development. Finally, the few existing studies regarding the influence of sex on breathing control in non-mammalian vertebrates will be discussed.
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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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12
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Pessa ME, Janes F, Gigli GL, Valente M. Sleep Disorders in Menopause: Review of the Literature and Occurrence through Menopausal Stages. Health (London) 2019. [DOI: 10.4236/health.2019.115041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Loiseau C, Cayetanot F, Joubert F, Perrin-Terrin AS, Cardot P, Fiamma MN, Frugiere A, Straus C, Bodineau L. Current Perspectives for the use of Gonane Progesteronergic Drugs in the Treatment of Central Hypoventilation Syndromes. Curr Neuropharmacol 2018; 16:1433-1454. [PMID: 28721821 PMCID: PMC6295933 DOI: 10.2174/1570159x15666170719104605] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/30/2017] [Accepted: 07/12/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Central alveolar hypoventilation syndromes (CHS) encompass neurorespiratory diseases resulting from congenital or acquired neurological disorders. Hypercapnia, acidosis, and hypoxemia resulting from CHS negatively affect physiological functions and can be lifethreatening. To date, the absence of pharmacological treatment implies that the patients must receive assisted ventilation throughout their lives. OBJECTIVE To highlight the relevance of determining conditions in which using gonane synthetic progestins could be of potential clinical interest for the treatment of CHS. METHODS The mechanisms by which gonanes modulate the respiratory drive were put into the context of those established for natural progesterone and other synthetic progestins. RESULTS The clinical benefits of synthetic progestins to treat respiratory diseases are mixed with either positive outcomes or no improvement. A benefit for CHS patients has only recently been proposed. We incidentally observed restoration of CO2 chemosensitivity, the functional deficit of this disease, in two adult CHS women by desogestrel, a gonane progestin, used for contraception. This effect was not observed by another group, studying a single patient. These contradictory findings are probably due to the complex nature of the action of desogestrel on breathing and led us to carry out mechanistic studies in rodents. Our results show that desogestrel influences the respiratory command by modulating the GABAA and NMDA signaling in the respiratory network, medullary serotoninergic systems, and supramedullary areas. CONCLUSION Gonanes show promise for improving ventilation of CHS patients, although the conditions of their use need to be better understood.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Laurence Bodineau
- Address correspondence to this author at the Sorbonne Universités, UPMC Univ. Paris 06, INSERM, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, F-75013, Paris, France; Tel: 33 1 40 77 97 15; Fax: 33 1 40 77 97 89; E-mail:
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Marques DA, de Carvalho D, da Silva GSF, Szawka RE, Anselmo-Franci JA, Bícego KC, Gargaglioni LH. Ventilatory, metabolic, and thermal responses to hypercapnia in female rats: effects of estrous cycle, ovariectomy, and hormonal replacement. J Appl Physiol (1985) 2015; 119:61-8. [DOI: 10.1152/japplphysiol.00254.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 04/23/2015] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to examine how estrous cycle, ovariectomy, and hormonal replacement affect the respiratory [ventilation (V̇e), tidal volume, and respiratory frequency], metabolic (V̇o2), and thermoregulatory (body temperature) responses to hypercapnia (7% CO2) in female Wistar rats. The parameters were measured in rats during different phases of the estrous cycle, and also in ovariectomized (OVX) rats supplemented with 17β-estradiol (OVX+E2), with a combination of E2 and progesterone (OVX+E2P), or with corn oil (OVX+O, vehicle). All experiments were conducted on day 8 after ovariectomy. The intact animals did not present alterations during normocapnia or under hypercapnia in V̇e, tidal volume, respiratory frequency, V̇o2, and V̇e/V̇o2 in the different phases of the estrous cycle. However, body temperature was higher in female rats on estrus. Hormonal replacement did not change the ventilatory, thermoregulatory, or metabolic parameters during hypercapnia, compared with the OVX animals. Nevertheless, OVX+E2, OVX+E2P, and OVX+O presented lower hypercapnic ventilatory responses compared with intact females on the day of estrus. Also, rats in estrus showed higher V̇e and V̇e/V̇o2 during hypercapnia than OVX animals. The data suggest that other gonadal factors, besides E2 and P, are possibly involved in these responses.
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Affiliation(s)
- Danuzia A. Marques
- Department of Animal Morphology and Physiology, São Paulo State University, UNESP FCAV at Jaboticabal, São Paulo, Brazil
| | | | - Glauber S. F. da Silva
- Department of Animal Morphology and Physiology, São Paulo State University, UNESP FCAV at Jaboticabal, São Paulo, Brazil
| | - Raphael E. Szawka
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Minas Gerais, Brazil; and
| | - Janete A. Anselmo-Franci
- Department of Morphology, Stomatology and Physiology, Dental School of Ribeirao Preto, University of São Paulo, São Paulo, Brazil
| | - Kênia C. Bícego
- Department of Animal Morphology and Physiology, São Paulo State University, UNESP FCAV at Jaboticabal, São Paulo, Brazil
| | - Luciane H. Gargaglioni
- Department of Animal Morphology and Physiology, São Paulo State University, UNESP FCAV at Jaboticabal, São Paulo, Brazil
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Mansukhani MP, Wang S, Somers VK. Chemoreflex physiology and implications for sleep apnoea: insights from studies in humans. Exp Physiol 2014; 100:130-5. [PMID: 25398715 DOI: 10.1113/expphysiol.2014.082826] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/07/2014] [Indexed: 12/31/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review summarizes chemoreflex physiology in health and disease, with specific focus on chemoreflex-mediated pathophysiology in obstructive and central sleep apnoea. What advances does it highlight? Chemoreflex mechanisms are thought to contribute significantly to the pathophysiology and adverse outcomes seen in sleep apnoea. Clinical implications of altered chemoreflex function in sleep apnoea from recent studies in humans, including cardiac arrhythmias, coronary artery disease, systolic/diastolic heart failure and sudden cardiac death are highlighted. Activation of the chemoreflex in response to hypoxaemia results in an increase in sympathetic neural outflow. This process is predominantly mediated by the peripheral chemoreceptors in the carotid bodies and is potentiated by the absence of the sympatho-inhibitory influence of ventilation during apnoea, as is seen in patients with sleep apnoea. In these patients, repetitive nocturnal hypoxaemia and apnoea elicit sympathetic activation, which may persist into wakefulness and is thought to contribute to the development of systemic hypertension and cardiac and vascular dysfunction. Chemoreflex activation could possibly lead to adverse cardiovascular outcomes, such as nocturnal myocardial infarction, systolic and/or diastolic heart failure, cardiac arrhythmias and sudden death in patients with sleep apnoea. This review summarizes chemoreflex physiology in health and disease, with specific focus on chemoreflex-mediated pathophysiology in obstructive and central sleep apnoea. Measurement of the chemoreflex response may serve as a potential avenue for individualized screening for cardiovascular disease. Whether modulation of this response in sleep apnoea may aid in the prevention and treatment of adverse cardiovascular consequences will require further study.
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Abstract
There is a growing public awareness that hormones can have a significant impact on most biological systems, including the control of breathing. This review will focus on the actions of two broad classes of hormones on the neuronal control of breathing: sex hormones and stress hormones. The majority of these hormones are steroids; a striking feature is that both groups are derived from cholesterol. Stress hormones also include many peptides which are produced primarily within the paraventricular nucleus of the hypothalamus (PVN) and secreted into the brain or into the circulatory system. In this article we will first review and discuss the role of sex hormones in respiratory control throughout life, emphasizing how natural fluctuations in hormones are reflected in ventilatory metrics and how disruption of their endogenous cycle can predispose to respiratory disease. These effects may be mediated directly by sex hormone receptors or indirectly by neurotransmitter systems. Next, we will discuss the origins of hypothalamic stress hormones and their relationship with the respiratory control system. This relationship is 2-fold: (i) via direct anatomical connections to brainstem respiratory control centers, and (ii) via steroid hormones released from the adrenal gland in response to signals from the pituitary gland. Finally, the impact of stress on the development of neural circuits involved in breathing is evaluated in animal models, and the consequences of early stress on respiratory health and disease is discussed.
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Affiliation(s)
- Mary Behan
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA.
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Abstract
This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions. There is a dynamic interplay between disturbances in acid-base balance, that is, exercise, that affect ventilation as well as imposed or pathological disturbances of ventilation that affect acid-base balance. Interactions between ventilation and acid-base balance are highlighted for moderate- to high-intensity exercise, altitude, induced acidosis and alkalosis, pregnancy, obesity, and some pathological conditions. In many situations, complete acid-base data are lacking, indicating a need for further research aimed at elucidating mechanistic bases for relationships between alterations in acid-base state and the ventilatory responses.
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Affiliation(s)
- Michael I Lindinger
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
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Gallego J. Genetic diseases: congenital central hypoventilation, Rett, and Prader-Willi syndromes. Compr Physiol 2013; 2:2255-79. [PMID: 23723037 DOI: 10.1002/cphy.c100037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The present review summarizes current knowledge on three rare genetic disorders of respiratory control, congenital central hypoventilation syndrome (CCHS), Rett syndrome (RTT), and Prader-Willi syndrome (PWS). CCHS is characterized by lack of ventilatory chemosensitivity caused by PHOX2B gene abnormalities consisting mainly of alanine expansions. RTT is associated with episodes of tachypneic and irregular breathing intermixed with breathholds and apneas and is caused by mutations in the X-linked MECP2 gene encoding methyl-CpG-binding protein. PWS manifests as sleep-disordered breathing with apneas and episodes of hypoventilation and is caused by the loss of a group of paternally inherited genes on chromosome 15. CCHS is the most specific disorder of respiratory control, whereas the breathing disorders in RTT and PWS are components of a more general developmental disorder. The main clinical features of these three disorders are reviewed with special emphasis on the associated brain abnormalities. In all three syndromes, disease-causing genetic defects have been identified, allowing the development of genetically engineered mouse models. New directions for future therapies based on these models or, in some cases, on clinical experience are delineated. Studies of CCHS, RTT, and PWS extend our knowledge of the molecular and cellular aspects of respiratory rhythm generation and suggest possible pharmacological approaches to respiratory control disorders. This knowledge is relevant for the clinical management of many respiratory disorders that are far more prevalent than the rare diseases discussed here.
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Affiliation(s)
- Jorge Gallego
- Inserm U676 and University of Paris Diderot, Paris, France.
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Domnik NJ, Turcotte SE, Yuen NY, Iscoe S, Fisher JT. CO(2) rebreathing: an undergraduate laboratory to study the chemical control of breathing. ADVANCES IN PHYSIOLOGY EDUCATION 2013; 37:361-369. [PMID: 24292914 DOI: 10.1152/advan.00075.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Read CO2 rebreathing method (Read DJ. A clinical method for assessing the ventilatory response to carbon dioxide. Australas Ann Med 16: 20-32, 1967) provides a simple and reproducible approach for studying the chemical control of breathing. It has been widely used since the modifications made by Duffin and coworkers. Our use of a rebreathing laboratory to challenge undergraduate science students to investigate the control of breathing provided 8 yr of student-generated data for comparison with the literature. Students (age: 19-22 yr, Research Ethics Board approval) rebreathed from a bag containing 5% CO2 and 95% O2 (to suppress the peripheral chemoreflex to hypoxia). Rebreathing was performed, and ventilation measured, after hyperventilation to deplete tissue CO2 stores and enable the detection of the central chemoreflex threshold. We analyzed 43 data sets, of which 10 were rejected for technical reasons. The mean threshold and ventilatory sensitivity to CO2 were 43.3 ± 3.8 mmHg and 4.60 ± 3.04 l·min(-1)·mmHg(-1) (means ± SD), respectively. Threshold values were normally distributed, whereas sensitivity was skewed to the left. Both mean values agreed well with those in the literature. We conclude that the modified rebreathing protocol is a robust method for undergraduate investigation of the chemical control of breathing.
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Affiliation(s)
- N J Domnik
- Department of Biomedical and Molecular Sciences, Physiology Program, Queen's University, Kingston, Ontario, Canada; and
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Ramanantsoa N, Gallego J. Congenital central hypoventilation syndrome. Respir Physiol Neurobiol 2013; 189:272-9. [PMID: 23692929 DOI: 10.1016/j.resp.2013.05.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/03/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Congenital central hypoventilation syndrome (CCHS) is characterized by hypoventilation during sleep and impaired ventilatory responses to hypercapnia and hypoxemia. Most cases are sporadic and caused by de novo PHOX2B gene mutations, which are usually polyalanine repeat expansions. Physiological and neuroanatomical studies of genetically engineered mice and analyses of cellular responses to mutated Phox2b have shed light on the pathophysiological mechanisms of CCHS. Findings in Phox2b(27Ala/+) knock-in mice consisted of unstable breathing with apneas, absence of the ventilatory response to hypercapnia, death within a few hours after birth, and absence of the retrotrapezoid nucleus (RTN). Conditional mouse mutants in which Phox2b(27Ala) was targeted to the RTN also lacked the ventilatory response to hypercapnia at birth but survived to adulthood and developed a partial hypercapnia response. The therapeutic effects of desogestrel are being evaluated in clinical trials, and recent analyses of cellular responses to polyAla Phox2b aggregates have suggested new pharmacological approaches designed to counteract the toxic effects of mutated Phox2b.
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Affiliation(s)
- N Ramanantsoa
- INSERM, U676, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Paris, France
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Stickland MK, Lindinger MI, Olfert IM, Heigenhauser GJF, Hopkins SR. Pulmonary gas exchange and acid-base balance during exercise. Compr Physiol 2013; 3:693-739. [PMID: 23720327 PMCID: PMC8315793 DOI: 10.1002/cphy.c110048] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
As the first step in the oxygen-transport chain, the lung has a critical task: optimizing the exchange of respiratory gases to maintain delivery of oxygen and the elimination of carbon dioxide. In healthy subjects, gas exchange, as evaluated by the alveolar-to-arterial PO2 difference (A-aDO2), worsens with incremental exercise, and typically reaches an A-aDO2 of approximately 25 mmHg at peak exercise. While there is great individual variability, A-aDO2 is generally largest at peak exercise in subjects with the highest peak oxygen consumption. Inert gas data has shown that the increase in A-aDO2 is explained by decreased ventilation-perfusion matching, and the development of a diffusion limitation for oxygen. Gas exchange data does not indicate the presence of right-to-left intrapulmonary shunt developing with exercise, despite recent data suggesting that large-diameter arteriovenous shunt vessels may be recruited with exercise. At the same time, multisystem mechanisms regulate systemic acid-base balance in integrative processes that involve gas exchange between tissues and the environment and simultaneous net changes in the concentrations of strong and weak ions within, and transfer between, extracellular and intracellular fluids. The physicochemical approach to acid-base balance is used to understand the contributions from independent acid-base variables to measured acid-base disturbances within contracting skeletal muscle, erythrocytes and noncontracting tissues. In muscle, the magnitude of the disturbance is proportional to the concentrations of dissociated weak acids, the rate at which acid equivalents (strong acid) accumulate and the rate at which strong base cations are added to or removed from muscle.
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Affiliation(s)
- Michael K. Stickland
- Division of Pulmonary Medicine, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Michael I. Lindinger
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - I. Mark Olfert
- Robert C. Byrd Health Sciences Center, Center for Cardiovascular and Respiratory Sciences, Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia
| | | | - Susan R. Hopkins
- Departments of Medicine and Radiology, University of California, San Diego, San Diego, California
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Gonzales GF. Serum testosterone levels and excessive erythrocytosis during the process of adaptation to high altitudes. Asian J Androl 2013; 15:368-74. [PMID: 23524530 DOI: 10.1038/aja.2012.170] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Populations living at high altitudes (HAs), particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis (16 g dl(-1)<haemoglobin (Hb)≤21 g dl(-1)) and others with excessive erythrocytosis (EE) (Hb>21 g dl(-1)). Elevated haemoglobin values (EE) are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate (DHEAS) to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity. Lower 17beta-HSD activity via Δ4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the Δ5-pathway. Currently, there are various situations in which people live (human biodiversity) with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.
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Affiliation(s)
- Gustavo F Gonzales
- High Altitude Research Institute and Department of Biological and Physiological Sciences, Faculty of Sciences and Philosophy, Universidad Peruana Cayetano Heredia, Lima 31, Peru.
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Davenport MH, Beaudin AE, Brown AD, Leigh R, Poulin MJ. Ventilatory responses to exercise and CO2 after menopause in healthy women: Effects of age and fitness. Respir Physiol Neurobiol 2012; 184:1-8. [DOI: 10.1016/j.resp.2012.06.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/01/2012] [Accepted: 06/19/2012] [Indexed: 11/28/2022]
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MacNutt MJ, De Souza MJ, Tomczak SE, Homer JL, Sheel AW. Resting and exercise ventilatory chemosensitivity across the menstrual cycle. J Appl Physiol (1985) 2012; 112:737-47. [DOI: 10.1152/japplphysiol.00727.2011] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that resting and exercise ventilatory chemosensitivity would be augmented in women when estrogen and progesterone levels are highest during the luteal phase of the menstrual cycle. Healthy, young females ( n = 10; age = 23 ± 5 yrs) were assessed across one complete cycle: during early follicular (EF), late follicular (LF), early luteal, and mid-luteal (ML) phases. We measured urinary conjugates of estrogen and progesterone daily. To compare values of ventilatory chemosensitivity and day-to-day variability of measures between sexes, males ( n = 10; age = 26 ± 7 yrs) were assessed on 5 nonconsecutive days during a 1-mo period. Resting ventilation was measured and hypoxic chemosensitivity assessed using an isocapnic hypoxic ventilatory response (iHVR) test. The hypercapnic ventilatory response was assessed using the Read rebreathing protocol and modified rebreathing tests. Participants completed submaximal cycle exercise in normoxia and hypoxia. We observed a significant effect of menstrual-cycle phase on resting minute ventilation, which was elevated in the ML phase relative to the EF and LF phases. Compared with males, resting end-tidal CO2was reduced in females during the EF and ML phases but not in the LF phase. We found that iHVR was unaffected by menstrual-cycle phase and was not different between males and females. The sensitivity to chemical stimuli was unaffected by menstrual-cycle phase, meaning that any hormone-mediated effect is of insufficient magnitude to exceed the inherent variation in these chemosensitivity measures. The ventilatory recruitment threshold for CO2was generally lower in women, which is suggestive of a hormonally related lowering of the ventilatory recruitment threshold. We detected no effect of menstrual-cycle phase on submaximal exercise ventilation and found that the ventilatory response to normoxic and hypoxic exercise was quantitatively similar between males and females. This suggests that feed-forward and feed-back influences during exercise over-ride the effects of naturally occurring changes in sex hormones.
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Affiliation(s)
- Meaghan J. MacNutt
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Mary Jane De Souza
- Department of Kinesiology, Pennsylvania State University, University Park, Pennsylvania
| | - Simone E. Tomczak
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - Jenna L. Homer
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and
| | - A. William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and
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Wang L, Green FHY, Smiley-Jewell SM, Pinkerton KE. Susceptibility of the aging lung to environmental injury. Semin Respir Crit Care Med 2010; 31:539-53. [PMID: 20941655 DOI: 10.1055/s-0030-1265895] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
With an ever-increasing number of elderly individuals in the world, a better understanding of the issues associated with aging and the environment is needed. The respiratory system is one of the primary interfaces between the body and the external environment. An expanding number of studies suggest that the aging pulmonary system (>65 years) is at increased risk for adverse health effects from environmental insult, such as by air pollutants, infection, and climate change. However, the mechanism(s) for increased susceptibility in this subpopulation are not well understood. In this review, we provide a limited but comprehensive overview of how the lung ages, examples of environmental exposures associated with injury to the aging lung, and potential mechanisms underlying the increased vulnerability of the aging lung to injury from environmental factors.
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Affiliation(s)
- Lei Wang
- Center for Health and the Environment, University of California at Davis, One Shields Ave., Davis, CA 95616, USA
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Jensen D, Mask G, Tschakovsky ME. Variability of the ventilatory response to Duffin's modified hyperoxic and hypoxic rebreathing procedure in healthy awake humans. Respir Physiol Neurobiol 2010; 170:185-97. [DOI: 10.1016/j.resp.2009.12.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 11/27/2022]
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