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Emans TW, Moraes DJA, Ben-Tal A, Barrett CJ, Paton JFR, McBryde FD. Forgotten Circulation: Reduced Mesenteric Venous Capacitance in Hypertensive Rats Is Improved by Decreasing Sympathetic Activity. Hypertension 2024; 81:823-835. [PMID: 38380519 DOI: 10.1161/hypertensionaha.123.21878] [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: 08/02/2023] [Accepted: 02/06/2024] [Indexed: 02/22/2024]
Abstract
BACKGROUND The mesenteric venous reservoir plays a vital role in mediating blood volume and pressure changes and is richly innervated by sympathetic nerves; however, the precise nature of venous sympathetic regulation and its role during hypertension remains unclear. We hypothesized that sympathetic drive to mesenteric veins in spontaneously hypertensive (SH) rats is raised, increasing mean circulatory filling pressure (MCFP), and impairing mesenteric capacitance. METHODS Arterial pressure, central venous pressure, mesenteric arterial, and venous blood flow were measured simultaneously in conscious male Wistar and SH rats. MCFP was assessed using an intraatrial balloon. Hemodynamic responses to volume changes (±20%) were measured before and after ganglionic blockade and carotid body denervation. Sympathetic venoconstrictor activity was measured in situ. RESULTS MCFP in vivo (10.8±1.6 versus 8.0±2.1 mm Hg; P=0.0005) and sympathetic venoconstrictor drive in situ (18±1 versus 10±2 µV; P<0.0001) were higher in SH rats; MCFP decreased in SH rats after hexamethonium and carotid body denervation (7.6±1.4; P<0.0001 and 8.5±1.0 mm Hg; P=0.0045). During volume changes, arterial pressure remained stable. With blood loss, net efflux of blood from the mesenteric bed was measured in both strains. However, during volume infusion, we observed net influx in Wistar (+2.3±2.6 mL/min) but efflux in SH rats (-1.0±1.0 mL/min; P=0.0032); this counterintuitive efflux was abolished by hexamethonium and carotid body denervation (+0.3±1.7 and 0.5±1.6 mL/min, respectively). CONCLUSIONS In SH rats, excessive sympathetic venoconstriction elevates MCFP and reduces capacitance, impairing volume buffering by mesenteric veins. We propose selective targeting of mesenteric veins through sympathetic drive reduction as a novel therapeutic opportunity for hypertension.
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Affiliation(s)
- Tonja W Emans
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand (T.W.E., A.B.-T., C.J.B., J.F.R.P., F.D.M.)
| | - Davi J A Moraes
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of São Paulo, Brazil (D.J.A.M.)
| | - Alona Ben-Tal
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand (T.W.E., A.B.-T., C.J.B., J.F.R.P., F.D.M.)
- Insightful Modelling Limited, Auckland, New Zealand (A.B.-T.)
| | - Carolyn J Barrett
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand (T.W.E., A.B.-T., C.J.B., J.F.R.P., F.D.M.)
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand (T.W.E., A.B.-T., C.J.B., J.F.R.P., F.D.M.)
| | - Fiona D McBryde
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand (T.W.E., A.B.-T., C.J.B., J.F.R.P., F.D.M.)
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2
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Hemingway HW, Richey RE, Moore AM, Saul BM, Shokraeifard AM, Cope HL, Olivencia-Yurvati AH, Cunningham RL, Smith ML, Romero SA. Effect of acute heat exposure on the pressor response to a voluntary hypoxic apnea. J Appl Physiol (1985) 2023; 135:542-548. [PMID: 37439242 PMCID: PMC10538993 DOI: 10.1152/japplphysiol.00245.2023] [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: 04/19/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/14/2023] Open
Abstract
The pressor response induced by a voluntary hypoxic apnea is mediated largely by increased sympathetic outflow. The neural control of blood pressure is altered in recovery from acute heat exposure, but its effect on the pressor response to a voluntary hypoxic apnea has never been explored. Therefore, we tested the hypothesis that prior heat exposure would attenuate the pressor response induced by a voluntary hypoxic apnea. Eleven healthy adults (five women) were exposed to whole body passive heating (water-perfused suit) sufficient to increase body core temperature by 1.2°C. Voluntary hypoxic apneas were performed at baseline and in recovery when body core temperature returned to ≤ 0.3°C of baseline. Participants breathed gas mixtures of varying [Formula: see text] (21%, 16%, and 12%; randomized) for 1 min followed by a 15-s end-expiratory apnea. The change in arterial oxygen saturation during each apnea did not differ from baseline to recovery (P = 0.6 for interaction), whereas the pressor response induced by a voluntary hypoxia apnea was reduced ([Formula: see text] 21%, baseline 17 ± 7 mmHg vs. recovery 14 ± 7 mmHg; [Formula: see text] 16%, baseline 24 ± 8 mmHg vs. recovery 18 ± 7 mmHg; [Formula: see text] 12%, baseline 28 ± 11 mmHg vs. recovery 24 ± 11 mmHg; P = 0.01 for main effect of time). These data suggest that prior heat exposure induces a cross-stressor effect such that the pressor response to a voluntary hypoxic apnea is attenuated.NEW & NOTEWORTHY The pressor response induced by a voluntary hypoxic apnea is mediated by increased sympathetic outflow. The neural control of blood pressure is altered in recovery from acute heat exposure, but its effect on the pressor response to a voluntary hypoxic apnea has never been explored. Our data suggest that prior heat exposure induces a cross-stressor effect such that the pressor response to a voluntary hypoxic apnea is attenuated.
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Affiliation(s)
- Holden W Hemingway
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Rauchelle E Richey
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Amy M Moore
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Benjamin M Saul
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Austin M Shokraeifard
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Heidi L Cope
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Albert H Olivencia-Yurvati
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
- Department of Surgery, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Rebecca L Cunningham
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Michael L Smith
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Steven A Romero
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Herberts M, Kolla B, Paul T, Mekala P, Mansukhani MP. Sleep apnea and autonomic dysfunction in patients with dementia. Front Neurosci 2022; 16:951147. [PMID: 36408398 PMCID: PMC9669746 DOI: 10.3389/fnins.2022.951147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022] Open
Abstract
Sleep apnea is common sleep disorder that is associated with an is an increase in risk of many health conditions, including systemic hypertension, stroke, atrial fibrillation, and heart failure. The predominant underlying pathophysiological mechanism for elevated risk of these conditions in patients with sleep apnea is thought to involve autonomic dysfunction in the form of sympathetic overactivity. Autonomic dysfunction is also associated with several neurodegenerative disorders and sleep apnea, in turn, has been shown to be associated with an increased risk of development of mild cognitive impairment and various types of dementia. Rapid eye movement sleep behavior disorder, which is also associated with an increased risk of alpha synucleiopathy-related dementia, is also linked with autonomic dysfunction. In this article we explore the relationship between sleep apnea, autonomic dysfunction, rapid eye movement sleep behavior disorder and dementia. This article describes the various autonomic dysfunction that are thought to occur in the context of sleep apnea. And illustrate the mechanisms by which sleep apnea, through its impact on autonomic dysfunction could potentially result in dementia. We also review the evidence examining the impact of treatment of sleep apnea on autonomic dysfunction and cognitive outcomes.
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Affiliation(s)
- Michelle Herberts
- Center for Sleep Medicine, Mayo Clinic, Rochester, MN, United States
| | | | - Travis Paul
- Mayo Clinic Health System, Southwest Minnesota, Mankato, MN, United States
| | - Praveen Mekala
- Mayo Clinic Health System, Southwest Minnesota, Mankato, MN, United States
| | - Meghna P. Mansukhani
- Center for Sleep Medicine, Mayo Clinic, Rochester, MN, United States
- *Correspondence: Meghna P. Mansukhani,
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Li HP, Wang HQ, Li N, Zhang L, Li SQ, Yan YR, Lu HH, Wang Y, Sun XW, Lin YN, Zhou JP, Li QY. Model for Identifying High Carotid Body Chemosensitivity in Patients with Obstructive Sleep Apnea. Nat Sci Sleep 2021; 13:493-501. [PMID: 33911906 PMCID: PMC8071699 DOI: 10.2147/nss.s299646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/07/2021] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE The carotid body (CB) is a major peripheral respiratory chemoreceptor. In patients with obstructive sleep apnea (OSA), high CB chemosensitivity (CBC) is associated with refractory hypertension and insulin resistance and known to further aggravate OSA. Thus, the identification of high CB (hCBC) among OSA patients is of clinical significance, but detection methods are still limited. Therefore, this study aimed to explore the association of CBC with OSA severity and to develop a simplified model that can identify patients with hCBC. METHODS In this cross-sectional study of subjects who underwent polysomnography (PSG), CBC was measured using the Dejours test. We defined hCBC as a decrease of >12% in respiratory rate (RR) after breathing of pure O2. The association of CBC with OSA severity was explored by logistic regression, and a model for identifying hCBC was constructed and confirmed using receiver operating characteristic analysis. RESULTS Patients with OSA (n=142) and individuals without OSA (n=38) were enrolled. CBC was higher in patients with OSA than in those without OSA (% decrease in RR, 15.2%±13.3% vs 9.1%±7.5%, P<0.05). Apnea-hypopnea index (AHI), fraction of apnea-hypopnea events in rapid-eye-movement sleep (Fevents-in-REM), and longest time of apnea (LTA) were associated with hCBC independently (odds ratio [OR]=1.048, OR=1.082, and OR=1.024 respectively; all P<0.05). The model for identifying hCBC allocated a score to each criterion according to its OR values, ie, 1 (LTA >48.4 s), 2 (AHI >15.7 events/hour), and 3 (Fevents-in-REM >12.7%). A score of 3 or greater indicated hCBC with a sensitivity of 79.4% and specificity of 88.2%. CONCLUSION High CBC is associated with the severity of OSA. A simplified scoring system based on clinical variables from PSG can be used to identify hCBC.
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Affiliation(s)
- Hong Peng Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Hai Qin Wang
- Xietu Community Health Service Center of Xuhui District, Shanghai, 200231, People's Republic of China
| | - Ning Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Liu Zhang
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Shi Qi Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Ya Ru Yan
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Huan Huan Lu
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Yi Wang
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Xian Wen Sun
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Ying Ni Lin
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Jian Ping Zhou
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
| | - Qing Yun Li
- Department of Respiratory and Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China.,Institute of Respiratory Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, People's Republic of China
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5
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Affiliation(s)
| | - Naima Covassin
- Department of Cardiovascular Diseases (N.C., V.K.S.), Mayo Clinic, Rochester, MN
| | - Virend K Somers
- Department of Cardiovascular Diseases (N.C., V.K.S.), Mayo Clinic, Rochester, MN
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6
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Endothelin contributes to the blood pressure rise triggered by hypoxia in severe obstructive sleep apnea. J Hypertens 2017; 35:118-124. [PMID: 27906839 DOI: 10.1097/hjh.0000000000001134] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) is strongly correlated with an increased risk of systemic hypertension. However, the link between systemic hypertension and nocturnal apneas remains incompletely understood. Animal studies suggest an implication of the endothelin system. The aim of the present study is to determine if endogenous endothelin plays a role in the increase in blood pressure observed during hypoxic episodes in OSA patients, in addition to peripheral chemoreflex and neural sympathetic activation. METHODS We assessed the effects of the nonspecific endothelin antagonist bosentan (500 mg; Tracleer; Actelion; Basel, Switzerland) on ventilation, hemodynamics, and muscle sympathetic nerve activity (MSNA) during normoxia and isocapnic hypoxia using a randomized, crossover, double-blinded, placebo-controlled study design, and in 13 severely untreated sleep apneic patients (age 50 ± 9 years, apnea-hypopnea index 35 ± 21/h). RESULTS Hypoxia increased blood pressure, MSNA, and minute ventilation as oxygen saturation decreased. Bosentan suppressed completely the increase in SBP during a 5-min hypoxic challenge (143 ± 5 mmHg during hypoxia vs. 133 ± 5 mmHg during normoxia with placebo and 127 ± 3 mmHg during hypoxia vs. 125 ± 3 mmHg during normoxia under bosentan, P = 0.023). DBP as well as the rise in MSNA and ventilation during isocapnic hypoxia did not differ between bosentan and placebo. CONCLUSION Endothelin contributes to the rise in SBP in response to acute hypoxia in patients with severely untreated OSA. This was not due to lower chemoreflex activation with bosentan.
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7
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Beaudin AE, Waltz X, Hanly PJ, Poulin MJ. Impact of obstructive sleep apnoea and intermittent hypoxia on cardiovascular and cerebrovascular regulation. Exp Physiol 2017; 102:743-763. [PMID: 28439921 DOI: 10.1113/ep086051] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/19/2017] [Indexed: 01/06/2023]
Abstract
NEW FINDINGS What is the topic of this review? This review examines the notion that obstructive sleep apnoea (OSA) and intermittent hypoxia (IH) have hormetic effects on vascular health. What advances does it highlight? Clinical (OSA patient) and experimental animal and human models report that IH is detrimental to vascular regulation. However, mild IH and, by extension, mild OSA also have physiological and clinical benefits. This review highlights clinical and experimental animal and human data linking OSA and IH to vascular disease and discusses how hormetic effects of OSA and IH relate to OSA severity, IH intensity and duration, and patient/subject age. Obstructive sleep apnoea (OSA) is associated with increased risk of cardiovascular and cerebrovascular disease, a consequence attributed in part to chronic intermittent hypoxia (IH) resulting from repetitive apnoeas during sleep. Although findings from experimental animal, and human, models have shown that IH is detrimental to vascular regulation, the severity of IH used in many of these animal studies [e.g. inspired fraction of oxygen (FI,O2) = 2-3%; oxygen desaturation index = 120 events h-1 ] is considerably greater than that observed in the majority of patients with OSA. This may also explain disparities between animal and recently developed human models of IH, where IH severity is, by necessity, less severe (e.g. FI,O2 = 10-12%; oxygen desaturation index = 15-30 events h-1 ). In this review, we highlight the current knowledge regarding the impact of OSA and IH on cardiovascular and cerebrovascular regulation. In addition, we critically discuss the recent notion that OSA and IH may have hormetic effects on vascular health depending on conditions such as OSA severity, IH intensity and duration, and age. In general, data support an independent causal link between OSA and vascular disease, particularly for patients with severe OSA. However, the data are equivocal for older OSA patients and patients with mild OSA, because advanced age and short-duration, low-intensity IH have been reported to provide a degree of protection against IH and ischaemic events such as myocardial infarction and stroke, respectively. Overall, additional studies are needed to investigate the beneficial/detrimental effects of mild OSA on the various vascular beds.
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Affiliation(s)
- Andrew E Beaudin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Xavier Waltz
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Laboratoire HP2, U1042, INSERM, Université Grenoble Alpes, Grenoble, France
| | - Patrick J Hanly
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Sleep Centre, Foothills Medical Centre, Calgary, AB, Canada
| | - Marc J Poulin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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Marmouch H, Arfa S, Graja S, Slim T, Khochtali I. Obstructive sleep apnea presenting as pseudopheochromocytoma. Pan Afr Med J 2016; 23:75. [PMID: 27217898 PMCID: PMC4862767 DOI: 10.11604/pamj.2016.23.75.8979] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 02/18/2016] [Indexed: 11/11/2022] Open
Abstract
A 52-year-old female with a history of poorly controlled resistant hypertension was admitted to our hospital with severe hypertension. She had a history of fatigue and intermittent episodes of palpitations. Laboratory evaluation was significant for elevated 24-h urinary catecholamine levels (3,5 times the upper normal levels). This case was presenting with a clinical and biochemical picture indistinguishable from that of pheochromocytoma. However, neither computed tomography nor meta-iodo-benzyl-guanidine scintigraphy detected any catecholamine-producing tumor in or outside the adrenal glands. Our patient was screened with full polysomnography because of heavy snoring, daytime somnolence and obesity. It revealed severe obstructive sleep apnea syndrome. After three months of continuous positive airway pressure therapy, the patient experienced resolution of his presenting symptoms, improved blood pressure control and normalization of his urinary catecholamine levels. This case highlights sleep disordered breathing as a potentially reversible cause of pseudo-pheochromocytoma.
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Affiliation(s)
- Hela Marmouch
- Department of Endocrinology and Internal Medecine, Fattouma Bourguiba University Hospital, Monastir, Tunisia
| | - Sondes Arfa
- Department of Endocrinology and Internal Medecine, Fattouma Bourguiba University Hospital, Monastir, Tunisia
| | - Sameh Graja
- Department of Endocrinology and Internal Medecine, Fattouma Bourguiba University Hospital, Monastir, Tunisia
| | - Tensim Slim
- Department of Endocrinology and Internal Medecine, Fattouma Bourguiba University Hospital, Monastir, Tunisia
| | - Ines Khochtali
- Department of Endocrinology and Internal Medecine, Fattouma Bourguiba University Hospital, Monastir, Tunisia
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Mansukhani MP, Kara T, Caples SM, Somers VK. Chemoreflexes, sleep apnea, and sympathetic dysregulation. Curr Hypertens Rep 2015; 16:476. [PMID: 25097113 DOI: 10.1007/s11906-014-0476-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Obstructive sleep apnea (OSA) and hypertension are closely linked conditions. Disordered breathing events in OSA are characterized by increasing efforts against an occluded airway while asleep, resulting in a marked sympathetic response. This is predominantly due to hypoxemia activating the chemoreflexes, resulting in reflex increases in sympathetic neural outflow. In addition, apnea - and the consequent lack of inhibition of the sympathetic system that occurs with lung inflation during normal breathing - potentiates central sympathetic outflow. Sympathetic activation persists into the daytime, and is thought to contribute to hypertension and other adverse cardiovascular outcomes. This review discusses chemoreflex physiology and sympathetic modulation during normal sleep, as well as the sympathetic dysregulation seen in OSA, its extension into wakefulness, and changes after treatment. Evidence supporting the role of the peripheral chemoreflex in the sympathetic dysregulation seen in OSA, including in the context of comorbid obesity, metabolic syndrome, and systemic hypertension, is reviewed. Finally, alterations in cardiovascular variability and other potential mechanisms that may play a role in the autonomic imbalance in OSA are also discussed.
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Affiliation(s)
- Meghna P Mansukhani
- Sleep Medicine, Affiliated Communities Medical Center, 101 Willmar Avenue SW, Willmar, MN, USA,
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10
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Iturriaga R, Andrade DC, Del Rio R. Enhanced carotid body chemosensory activity and the cardiovascular alterations induced by intermittent hypoxia. Front Physiol 2014; 5:468. [PMID: 25520668 PMCID: PMC4251310 DOI: 10.3389/fphys.2014.00468] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/14/2014] [Indexed: 02/03/2023] Open
Abstract
The carotid body (CB) plays a main role in the maintenance of the oxygen homeostasis. The hypoxic stimulation of the CB increases the chemosensory discharge, which in turn elicits reflex sympathetic, cardiovascular, and ventilatory adjustments. An exacerbate carotid chemosensory activity has been associated with human sympathetic-mediated diseases such as hypertension, insulin resistance, heart failure, and obstructive sleep apnea (OSA). Indeed, the CB chemosensory discharge becomes tonically hypereactive in experimental models of OSA and heart failure. Chronic intermittent hypoxia (CIH), a main feature of OSA, enhances CB chemosensory baseline discharges in normoxia and in response to hypoxia, inducing sympathetic overactivity and hypertension. Oxidative stress, increased levels of ET-1, Angiotensin II and pro-inflammatory cytokines, along with a reduced production of NO in the CB, have been associated with the enhanced carotid chemosensory activity. In this review, we will discuss new evidence supporting a main role for the CB chemoreceptor in the autonomic and cardiorespiratory alterations induced by intermittent hypoxia, as well as the molecular mechanisms involved in the CB chemosensory potentiation.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - David C Andrade
- Laboratorio de Neurobiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
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11
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Del Rio R, Moya EA, Iturriaga R. Carotid body potentiation during chronic intermittent hypoxia: implication for hypertension. Front Physiol 2014; 5:434. [PMID: 25429271 PMCID: PMC4228839 DOI: 10.3389/fphys.2014.00434] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/24/2014] [Indexed: 11/30/2022] Open
Abstract
Autonomic dysfunction is involved in the development of hypertension in humans with obstructive sleep apnea, and animals exposed to chronic intermittent hypoxia (CIH). It has been proposed that a crucial step in the development of the hypertension is the potentiation of the carotid body (CB) chemosensory responses to hypoxia, but the temporal progression of the CB chemosensory, autonomic and hypertensive changes induced by CIH are not known. We tested the hypothesis that CB potentiation precedes the autonomic imbalance and the hypertension in rats exposed to CIH. Thus, we studied the changes in CB chemosensory and ventilatory responsiveness to hypoxia, the spontaneous baroreflex sensitivity (BRS), heart rate variability (HRV) and arterial blood pressure in pentobarbital anesthetized rats exposed to CIH for 7, 14, and 21 days. After 7 days of CIH, CB chemosensory and ventilatory responses to hypoxia were enhanced, while BRS was significantly reduced by 2-fold in CIH-rats compared to sham-rats. These alterations persisted until 21 days of CIH. After 14 days, CIH shifted the HRV power spectra suggesting a predominance of sympathetic over parasympathetic tone. In contrast, hypertension was found after 21 days of CIH. Concomitant changes between the gain of spectral HRV, BRS, and ventilatory hypoxic chemoreflex showed that the CIH-induced BRS attenuation preceded the HRV changes. CIH induced a simultaneous decrease of the BRS gain along with an increase of the hypoxic ventilatory gain. Present results show that CIH-induced persistent hypertension was preceded by early changes in CB chemosensory control of cardiorespiratory and autonomic function.
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Affiliation(s)
- Rodrigo Del Rio
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile ; Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
| | - Esteban A Moya
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Departamento Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
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Angheben JMM, Schoorlemmer GHM, Rossi MV, Silva TA, Cravo SL. Cardiovascular responses induced by obstructive apnea are enhanced in hypertensive rats due to enhanced chemoreceptor responsivity. PLoS One 2014; 9:e86868. [PMID: 24466272 PMCID: PMC3900660 DOI: 10.1371/journal.pone.0086868] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 12/17/2013] [Indexed: 11/17/2022] Open
Abstract
Spontaneously hypertensive rats (SHR), like patients with sleep apnea, have hypertension, increased sympathetic activity, and increased chemoreceptor drive. We investigated the role of carotid chemoreceptors in cardiovascular responses induced by obstructive apnea in awake SHR. A tracheal balloon and vascular cannulas were implanted, and a week later, apneas of 15 s each were induced. The effects of apnea were more pronounced in SHR than in control rats (Wistar Kyoto; WKY). Blood pressure increased by 57±3 mmHg during apnea in SHR and by 28±3 mmHg in WKY (p<0.05, n = 14/13). The respiratory effort increased by 53±6 mmHg in SHR and by 34±5 mmHg in WKY. The heart rate fell by 209±19 bpm in SHR and by 155±16 bpm in WKY. The carotid chemoreceptors were then inactivated by the ligation of the carotid body artery, and apneas were induced two days later. The inactivation of chemoreceptors reduced the responses to apnea and abolished the difference between SHR and controls. The apnea-induced hypertension was 11±4 mmHg in SHR and 8±4 mmHg in WKY. The respiratory effort was 15±2 mmHg in SHR and 15±2 mmHg in WKY. The heart rate fell 63±18 bpm in SHR and 52±14 bpm in WKY. Similarly, when the chemoreceptors were unloaded by the administration of 100% oxygen, the responses to apnea were reduced. In conclusion, arterial chemoreceptors contribute to the responses induced by apnea in both strains, but they are more important in SHR and account for the exaggerated responses of this strain to apnea.
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Affiliation(s)
- Juliana M M Angheben
- Department of Physiology, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, Brazil
| | - Guus H M Schoorlemmer
- Department of Physiology, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, Brazil
| | - Marcio V Rossi
- Department of Physiology, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, Brazil
| | - Thiago A Silva
- Department of Physiology, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, Brazil
| | - Sergio L Cravo
- Department of Physiology, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo, Brazil
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Bathina CS, Rajulapati A, Franzke M, Yamamoto K, Cunningham JT, Mifflin S. Knockdown of tyrosine hydroxylase in the nucleus of the solitary tract reduces elevated blood pressure during chronic intermittent hypoxia. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1031-9. [PMID: 24049117 DOI: 10.1152/ajpregu.00260.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Noradrenergic A2 neurons in nucleus tractus solitarius (NTS) respond to stressors such as hypoxia. We hypothesize that tyrosine hydroxylase (TH) knockdown in NTS reduces cardiovascular responses to chronic intermittent hypoxia (CIH), a model of the arterial hypoxemia observed during sleep apnea in humans. Adult male Sprague-Dawley rats were implanted with radiotelemetry transmitters and adeno-associated viral constructs with green fluorescent protein (GFP) reporter having either short hairpin RNA (shRNA) for TH or scrambled virus (scRNA) were injected into caudal NTS. Virus-injected rats were exposed to 7 days of CIH (alternating periods of 10% O2 and of 21% O2 from 8 AM to 4 PM; from 4 PM to 8 AM rats were exposed to 21% O2). CIH increased mean arterial pressure (MAP) and heart rate (HR) during the day in both the scRNA (n = 14, P < 0.001 MAP and HR) and shRNA (n = 13, P < 0.001 MAP and HR) groups. During the night, MAP and HR remained elevated in the scRNA rats (P < 0.001 MAP and HR) but not in the shRNA group. TH immunoreactivity and protein were reduced in the shRNA group. FosB/ΔFosB immunoreactivity was decreased in paraventricular nucleus (PVN) of shRNA group (P < 0.001). However, the shRNA group did not show any change in the FosB/ΔFosB immunoreactivity in the rostral ventrolateral medulla. Exposure to CIH increased MAP which persisted beyond the period of exposure to CIH. Knockdown of TH in the NTS reduced this CIH-induced persistent increase in MAP and reduced the transcriptional activation of PVN. This indicates that NTS A2 neurons play a role in the cardiovascular responses to CIH.
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Affiliation(s)
- Chandra Sekhar Bathina
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, Texas
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Gulemetova R, Drolet G, Kinkead R. Neonatal stress augments the hypoxic chemoreflex of adult male rats by increasing AMPA receptor-mediated modulation. Exp Physiol 2013; 98:1312-24. [DOI: 10.1113/expphysiol.2013.072090] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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15
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Ortiz FC, Del Rio R, Ebensperger G, Reyes VR, Alcayaga J, Varas R, Iturriaga R. Inhibition of rat carotid body glomus cells TASK-like channels by acute hypoxia is enhanced by chronic intermittent hypoxia. Respir Physiol Neurobiol 2013; 185:600-7. [DOI: 10.1016/j.resp.2012.11.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 01/19/2023]
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Del Rio R, Muñoz C, Arias P, Court FA, Moya EA, Iturriaga R. Chronic intermittent hypoxia-induced vascular enlargement and VEGF upregulation in the rat carotid body is not prevented by antioxidant treatment. Am J Physiol Lung Cell Mol Physiol 2011; 301:L702-11. [PMID: 21821731 DOI: 10.1152/ajplung.00128.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH), a characteristic of sleep obstructive apnea, enhances carotid body (CB) chemosensory responses to hypoxia, but its consequences on CB vascular area and VEGF expression are unknown. Accordingly, we studied the effect of CIH on CB volume, glomus cell numbers, blood vessel diameter and number, and VEGF immunoreactivity (VEGF-ir) in male Sprague-Dawley rats exposed to 5% O(2), 12 times/h for 8 h or sham condition for 21 days. We found that CIH did not modify the CB volume or the number of glomus cells but increased VEGF-ir and enlarged the vascular area by increasing the size of the blood vessels, whereas the number of the vessels was unchanged. Because oxidative stress plays an essential role in the CIH-induced carotid chemosensory potentiation, we tested whether antioxidant treatment with ascorbic acid may impede the vascular enlargement and the VEGF upregulation. Ascorbic acid, which prevents the CB chemosensory potentiation, failed to impede the vascular enlargement and the increased VEGF-ir. Thus present results suggest that the CB vascular enlargement induced by CIH is a direct effect of intermittent hypoxia and not secondary to the oxidative stress. Accordingly, the subsequent capillary changes may be secondary to the mechanisms involved in the neural chemosensory plasticity induced by intermittent hypoxia.
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Affiliation(s)
- Rodrigo Del Rio
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
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Del Rio R, Moya EA, Iturriaga R. Differential expression of pro-inflammatory cytokines, endothelin-1 and nitric oxide synthases in the rat carotid body exposed to intermittent hypoxia. Brain Res 2011; 1395:74-85. [PMID: 21555119 DOI: 10.1016/j.brainres.2011.04.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 03/30/2011] [Accepted: 04/15/2011] [Indexed: 12/30/2022]
Abstract
The enhanced carotid body (CB) chemosensory response to hypoxia induced by chronic intermittent hypoxia (CIH) has been attributed to oxidative stress, which is expected to increase the expression of chemosensory modulators including chemoexcitatory pro-inflammatory cytokines in the CB. Accordingly, we studied the time-course of the changes in the immunohistological expression of TNF-α, IL-1β, IL-6, ET-1, iNOS, eNOS and 3-nitrotyrosine in the CB, along with the progression of enhanced CB chemosensory responses to acute hypoxia in male Sprague-Dawley rats exposed to CIH (5%O₂, 12 times/h per 8h) for 7, 14 and 21 days. Exposure to CIH for 7 days resulted in a sustained potentiation of CB chemosensory responses to acute hypoxia, which persisted until 21 days of CIH. The chemosensory potentiation was paralleled by an increased 3-nitrotyrosine expression in the CB. On the contrary, CIH produced a transient 2-fold increase of ET-1 immunoreactivity at 7 days, a decrease in eNOS immunoreactivity, and a delayed but progressive increase of TNF-α, IL-1β and iNOS immunoreactivity, which was not associated with changes in systemic plasma levels or immune cell invasion within the CB. Thus, present results suggest that the local expression of chemosensory modulators and pro-inflammatory cytokines in the CB may have different temporal contribution to the CB chemosensory potentiation induced by CIH.
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Affiliation(s)
- Rodrigo Del Rio
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
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Chronic intermittent hypoxia reduces neurokinin-1 (NK(1)) receptor density in small dendrites of non-catecholaminergic neurons in mouse nucleus tractus solitarius. Exp Neurol 2010; 223:634-44. [PMID: 20206166 DOI: 10.1016/j.expneurol.2010.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 02/18/2010] [Accepted: 02/21/2010] [Indexed: 12/16/2022]
Abstract
Chronic intermittent hypoxia (CIH) is a frequent concomitant of sleep apnea, which can increase sympathetic nerve activity through mechanisms involving chemoreceptor inputs to the commissural nucleus of the solitary tract (cNTS). These chemosensory inputs co-store glutamate and substance P (SP), an endogenous ligand for neurokinin-1 (NK(1)) receptors. Acute hypoxia results in internalization of NK(1) receptors, suggesting that CIH also may affect the subcellular distribution of NK(1) receptors in subpopulations of cNTS neurons, some of which may express tyrosine hydroxylase, the rate-limiting enzyme for catecholamine synthesis (TH). To test this hypothesis, we examined dual immunolabeling for the NK(1) receptor and TH in the cNTS of male mice subjected to 10days or 35days of CIH or intermittent air. Electron microscopy revealed that NK(1) receptors and TH were almost exclusively localized within separate somatodendritic profiles in cNTS of control mice. In dendrites, immunogold particles identifying NK(1) receptors were prevalent in the cytoplasm and on the plasmalemmal surface. Compared with controls, CIH produced a significant region-specific decrease in the cytoplasmic (10 and 35days, P<0.05, unpaired Student t-test) and extrasynaptic plasmalemmal (35days, P<0.01, unpaired Student t-test) density of NK(1) immunogold particles exclusively in small (<0.1microm) dendrites without TH immunoreactivity. These results suggest that CIH produces a duration-dependent reduction in the availability of NK(1) receptors preferentially in small dendrites of non-catecholaminergic neurons in the cNTS. The implications of our findings are discussed with respect to their potential involvement in the slowly developing hypertension seen in sleep apnea patients.
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Iturriaga R, Moya EA, Del Rio R. Carotid body potentiation induced by intermittent hypoxia: Implications for cardiorespiratory changes induced by sleep apnoea. Clin Exp Pharmacol Physiol 2009; 36:1197-204. [DOI: 10.1111/j.1440-1681.2009.05213.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Montandon G, Horner RL, Kinkead R, Bairam A. Caffeine in the neonatal period induces long-lasting changes in sleep and breathing in adult rats. J Physiol 2009; 587:5493-507. [PMID: 19770189 DOI: 10.1113/jphysiol.2009.171918] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Caffeine is commonly used clinically to treat apnoeas and unstable breathing associated with premature birth. Caffeine antagonizes adenosine receptors and acts as an efficient respiratory stimulant in neonates. Owing to its persistent effects on adenosine receptor expression in the brain, neonatal caffeine administration also has significant effects on maturation of the respiratory control system. However, since adenosine receptors are critically involved in sleep regulation, and sleep also modulates breathing, we tested the hypothesis that neonatal caffeine treatment disrupts regulation of sleep and breathing in the adult rat. Neonatal caffeine treatment (15 mg kg(-1) day(-1)) was administered from postnatal days 3-12. At adulthood (8-10 weeks old), sleep and breathing were measured with a telemetry system and whole-body plethysmography respectively. In adult rats treated with caffeine during the neonatal period, sleep time was reduced, sleep onset latency was increased, and non-rapid eye movement (non-REM) sleep was fragmented compared to controls. Ventilation at rest was higher in caffeine-treated adult rats compared to controls across sleep/wake states. Hypercapnic ventilatory responses were significantly reduced in caffeine-treated rats compared to control rats across sleep/wake states. Additional experiments in adult anaesthetized rats showed that at similar levels of arterial blood gases, phrenic nerve activity was enhanced in caffeine-treated rats. This study demonstrates that administration of caffeine in the neonatal period alters respiratory control system activity in awake and sleeping rats, as well as in the anaesthetized rats, and also has persistent disrupting effects on sleep that are apparent in adult rats.
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Affiliation(s)
- Gaspard Montandon
- Departments of Medicine and Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada.
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Abstract
1. We believe that the ultimate goal of cardiovascular regulatory mechanisms is not the regulation of arterial blood pressure (BP), but the maintenance of tissue blood flows commensurate with metabolic requirements. Thus, elevated BP can potentially contribute to optimizing tissue blood flows under select circumstances; for example, when there are primary defects in autoregulation of tissue blood flows. 2. The hypothesis that a primary defect in autoregulation of tissue blood flows may be responsible for the development of hypertension is presented. It is argued that, in this context, at least part of the rise in BP may be reflexly driven by a 'metaboreflex', a homeostatic mechanism acting to regulate tissue blood flows. 3. We argue that in the context of primary defects in autoregulation of tissue blood flows, the ability to generate and sustain a hypertensive phenotype increases the lifespan of species (i.e. if it were not for this adaptive hypertensive phenotype, death due to circulatory failure would occur much earlier). 4. Experimental and clinical evidence that indirectly supports the hypothesis is reviewed briefly and a means for testing this hypothesis is suggested.
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Affiliation(s)
- E S Prakash
- Faculty of Medicine, AIMST University, Bedong, Kedah, Malaysia.
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Obstructive sleep apnea, immuno-inflammation, and atherosclerosis. Semin Immunopathol 2009; 31:113-25. [PMID: 19404644 DOI: 10.1007/s00281-009-0148-5] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 04/07/2009] [Indexed: 12/17/2022]
Abstract
Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder leading to cardiovascular and metabolic complications. OSA is also a multicomponent disorder, with intermittent hypoxia (IH) as the main trigger for the associated cardiovascular and metabolic alterations. Indeed, recurrent pharyngeal collapses during sleep lead to repetitive sequences of hypoxia-reoxygenation. This IH induces several consequences such as hemodynamic, hormonometabolic, oxidative, and immuno-inflammatory alterations that may interact and aggravate each other, resulting in artery changes, from adaptive to degenerative atherosclerotic remodeling. Atherosclerosis has been found in OSA patients free of other cardiovascular risk factors and is related to the severity of nocturnal hypoxia. Early stages of artery alteration, including functional and structural changes, have been evidenced in both OSA patients and rodents experimentally exposed to IH. Impaired vasoreactivity with endothelial dysfunction and/or increased vasoconstrictive responses due to sympathetic, endothelin, and renin-angiotensin systems have been reported and also contribute to vascular remodeling and inflammation. Oxidative stress, inflammation, and vascular remodeling can be directly triggered by IH, further aggravated by the OSA-associated hormonometabolic alterations, such as insulin resistance, dyslipidemia, and adipokine imbalance. As shown in OSA patients and in the animal model, genetic susceptibility, comorbidities (obesity), and life habits (high fat diet) may aggravate atherosclerosis development or progression. The intimate molecular mechanisms are still largely unknown, and their understanding may contribute to delineate new targets for prevention strategies and/or development of new treatment of OSA-related atherosclerosis, especially in patients at risk for cardiovascular disease.
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Sustained effect of continuous positive airway pressure on baroreflex sensitivity in congestive heart failure patients with obstructive sleep apnea. J Hypertens 2008; 26:1163-8. [DOI: 10.1097/hjh.0b013e3282fb81ed] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Bavis RW, Mitchell GS. Long-term effects of the perinatal environment on respiratory control. J Appl Physiol (1985) 2008; 104:1220-9. [DOI: 10.1152/japplphysiol.01086.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The respiratory control system exhibits considerable plasticity, similar to other regions of the nervous system. Plasticity is a persistent change in system behavior triggered by experiences such as changes in neural activity, hypoxia, and/or disease/injury. Although plasticity is observed in animals of all ages, some forms of plasticity appear to be unique to development (i.e., “developmental plasticity”). Developmental plasticity is an alteration in respiratory control induced by experiences during “critical” developmental periods; similar experiences outside the critical period will have little or no lasting effect. Thus complementary experiments on both mature and developing animals are generally needed to verify that the observed plasticity is unique to development. Frequently studied models of developmental plasticity in respiratory control include developmental manipulations of respiratory gas concentrations (O2and CO2). Environmental factors not specifically associated with breathing may also trigger developmental plasticity, however, including psychological stress or chemicals associated with maternal habits (e.g., nicotine, cocaine). Despite rapid advances in describing models of developmental plasticity in breathing, our understanding of fundamental mechanisms giving rise to such plasticity is poor; mechanistic studies of developmental plasticity are of considerable importance. Developmental plasticity may enable organisms to “fine tune” their phenotype to optimize the performance of this critical homeostatic regulatory system. On the other hand, developmental plasticity could also increase the risk of disease later in life. Future directions for studies concerning the mechanisms and functional implications of developmental plasticity in respiratory motor control are discussed.
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Kinkead R, Balon N, Genest SE, Gulemetova R, Laforest S, Drolet G. Neonatal maternal separation and enhancement of the inspiratory (phrenic) response to hypoxia in adult rats: disruption of GABAergic neurotransmission in the nucleus tractus solitarius. Eur J Neurosci 2008; 27:1174-88. [DOI: 10.1111/j.1460-9568.2008.06082.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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26
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Sadikot S. A clinical overview: Obstructive sleep apnea and hypertension. Diabetes Metab Syndr 2008. [DOI: 10.1016/j.dsx.2007.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Sadikot S. An overview: Obstructive Sleep Apnea and the Metabolic Syndrome: Should “X” be changed to “Zzz…Zzzz….Zzzzzzzzz….Zzz”? Diabetes & Metabolic Syndrome: Clinical Research & Reviews 2007. [DOI: 10.1016/j.dsx.2007.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Fournier S, Allard M, Gulemetova R, Joseph V, Kinkead R. Chronic corticosterone elevation and sex-specific augmentation of the hypoxic ventilatory response in awake rats. J Physiol 2007; 584:951-62. [PMID: 17855755 PMCID: PMC2277008 DOI: 10.1113/jphysiol.2007.141655] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Perinatal stress disrupts normal development of the hypothalamo-pituitary-adrenal (HPA) axis. Adult male (but not female) rats previously subjected to a stress such as neonatal maternal separation (NMS) are characterized by chronic elevation of plasma corticosterone (Cort) levels and an abnormally elevated hypoxic ventilatory response through mechanisms that remain unknown. The present study tested the hypothesis that a chronic increase of plasma Cort levels alone augments the ventilatory response to hypoxia in adult rats. Three groups of Sprague-Dawley male and female rats were used (control, placebo and Cort implants). Rats subjected to chronic Cort elevation received a subcutaneous Cort implant (300 mg) 14 days prior to ventilatory measurements, whereas sham-operated rats received placebo implants. Controls received no treatment. Plasma Cort levels and body weight profiles were measured to assess protocol efficiency. Whole body plethysmography was used to measure ventilatory activity and metabolic indices during normoxia and following a 20 min period of moderate hypoxia (12% O(2)). Male rats implanted with Cort showed a ventilatory response to hypoxia higher than placebo-treated rats; this effect was mainly due to a larger tidal volume response. In females, Cort treatment increased the breathing frequency response but the effect on minute ventilation was not significant. Taken together, these data show that chronic elevation of Cort alone increases the ventilatory response to hypoxia, but in a sex-specific manner. These data raise important questions regarding the mechanisms underlying the sexual dimorphism of this effect and the potential link between HPA axis dysfunction and respiratory disorders related to abnormal ventilatory chemoreflex.
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Affiliation(s)
- Sebastien Fournier
- Department of Pediatrics, Centre de Recherche Hospitalier Universitaire de Québec, Université Laval, Québec, QC, Canada
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Genest SE, Balon N, Laforest S, Drolet G, Kinkead R. Neonatal maternal separation and enhancement of the hypoxic ventilatory response in rat: the role of GABAergic modulation within the paraventricular nucleus of the hypothalamus. J Physiol 2007; 583:299-314. [PMID: 17569732 PMCID: PMC2277229 DOI: 10.1113/jphysiol.2007.135160] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neonatal maternal separation (NMS) affects respiratory control development as adult male (but not female) rats previously subjected to NMS show a hypoxic ventilatory response 25% greater than controls. The paraventricular nucleus of the hypothalamus (PVN) is an important modulator of respiratory activity. In the present study, we hypothesized that in awake rats, altered GABAergic inhibition within the PVN contributes to the enhancement of hypoxic ventilatory response observed in rats previously subjected to NMS. During normoxia, the increase in minute ventilation following microinjection of bicuculline (1 mm) within the PVN is greater in NMS versus control rats. These data show that regulation of ventilatory activity related to tonic inhibition of the PVN is more important in NMS than control rats. Microinjection of GABA or muscimol (1 mM) attenuated the ventilatory response to hypoxia (12% O2) in NMS rats only. The higher efficiency of microinjections in NMS rats is supported by results from GABAA receptor autoradiography which revealed a 22% increase in GABAA receptor binding sites within the PVN of NMS rats versus controls. Despite this increase, however, NMS rats still show a larger hypoxic ventilatory response than controls, suggesting that within the PVN the larger number of GABAA receptors either compensate for (1) a deficient GABAergic modulation, (2) an increase in the efficacy of excitatory inputs converging onto this structure, or (3) both. Together, these results show that the life-long consequences of NMS are far reaching as they can compromise the development of vital homeostatic function in a way that may predispose to respiratory disorders.
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Affiliation(s)
- Sophie-Emmanuelle Genest
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Norbert Balon
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Sylvie Laforest
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Guy Drolet
- Neuroscience Research Units, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
| | - Richard Kinkead
- Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université LavalQuébec, QC, Canada
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Schultz HD, Li YL, Ding Y. Arterial chemoreceptors and sympathetic nerve activity: implications for hypertension and heart failure. Hypertension 2007; 50:6-13. [PMID: 17502495 DOI: 10.1161/hypertensionaha.106.076083] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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31
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