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The Cardiovascular and Metabolic Effects of Chronic Hypoxia in Animal Models: A Mini-Review
Animal models are useful to understand the myriad physiological effects of hypoxia. Such models attempt to recapitulate the hypoxemia of human disease in various ways. In this mini-review, we consider the various animal models which have been deployed to understand the effects of chronic hypoxia on pulmonary and systemic blood pressure, glucose and lipid metabolism, atherosclerosis, and stroke. Chronic sustained hypoxia (CSH)—a model of chronic lung or heart diseases in which hypoxemia may be longstanding and persistent, or of high altitude, in which effective atmospheric oxygen concentration is low—reliably induces pu...
Source: Frontiers in Physiology - March 31, 2022 Category: Physiology Source Type: research

The effect of obesity, hypertension, diabetes mellitus, alcohol, and sleep apnea on the risk of atrial fibrillation
Physiol Res. 2021 Dec 30;70(Suppl4):S511-S525.ABSTRACTAtrial fibrillation (AF) is the most common sustained cardiac arrhythmia associated with a two-fold increase in mortality caused by a higher risk of stroke and heart failure. Currently, AF is present in ~ 2 % of the general population, and its incidence and prevalence are increasing. Obesity, hypertension, diabetes mellitus, obstructive sleep apnea, and alcohol consumption increase the risk of AF. Each unit of increase in BMI increases the risk of AF by 3 %, and intensive weight loss is also associated with reduced AF recurrence. Hypertension increases the risk of AF by...
Source: Physiological Research - February 24, 2022 Category: Physiology Authors: Z Čarná P Osman čík Source Type: research

Hypoxic Regulation of the Large-Conductance, Calcium and Voltage-Activated Potassium Channel, BK
Hypoxia is a condition characterized by a reduction of cellular oxygen levels derived from alterations in oxygen balance. Hypoxic events trigger changes in cell-signaling cascades, oxidative stress, activation of pro-inflammatory molecules, and growth factors, influencing the activity of various ion channel families and leading to diverse cardiovascular diseases such as myocardial infarction, ischemic stroke, and hypertension. The large-conductance, calcium and voltage-activated potassium channel (BK) has a central role in the mechanism of oxygen (O2) sensing and its activity has been related to the hypoxic response. BK ch...
Source: Frontiers in Physiology - December 22, 2021 Category: Physiology Source Type: research

The Importance of Sleep Fragmentation on the Hemodynamic Dipping in Obstructive Sleep Apnea Patients
ConclusionIn this study, we demonstrated that in OSA, the physiological dipping in SBP and SV decreased, and the variation of all investigated parameters increased. Hierarchical regression analysis indicates that the addition of the AI to BMI, age, and AHI increases the prediction of the HP evolution following sleep onset for both SBP and SV and may be the most important variable.
Source: Frontiers in Physiology - March 12, 2020 Category: Physiology Source Type: research

Atrial Transcriptional Profiles of Molecular Targets Mediating Electrophysiological Function in Aging and Pgc-1 β Deficient Murine Hearts
Conclusion: These findings limit the possible roles of gene transcriptional changes in previously reported age-dependent pro-arrhythmic electrophysiologial changes observed in Pgc-1β-/- atria to an altered Ca2+-ATPase (Atp2a2) expression. This directly parallels previously reported arrhythmic mechanism associated with p21-activated kinase type 1 deficiency. This could add to contributions from the direct physiological outcomes of mitochondrial dysfunction, whether through reactive oxygen species (ROS) production or altered Ca2+ homeostasis. Introduction Atrial arrhythmias constitute a major public health pro...
Source: Frontiers in Physiology - April 23, 2019 Category: Physiology Source Type: research

Is Aberrant Reno-Renal Reflex Control of Blood Pressure a Contributor to Chronic Intermittent Hypoxia-Induced Hypertension?
This study demonstrated unaltered vascular conductance in response to lumbar sympathetic stimulation in CIH-exposed rats. Aortic compliance was increased and estimated blood volume was unchanged in CIH-exposed rats. Increased blood pressure was related to an increase in cardiac output, which was confirmed by echocardiography (Lucking et al., 2014). It is suggested therefore that hypertension in the CIH model can be evoked by over-excitation of the cardiac arm of sympathetic nervous system (SNS), even before mechanisms of enhanced peripheral vasoconstriction and endothelial dysfunction are initiated (Naghshin et al., 2009)....
Source: Frontiers in Physiology - April 23, 2019 Category: Physiology Source Type: research

Sickle Cell Disease Subjects Have a Distinct Abnormal Autonomic Phenotype Characterized by Peripheral Vasoconstriction With Blunted Cardiac Response to Head-Up Tilt
Conclusion We have shown that SCD subjects are much more likely than non-SCD subjects to have impaired cardiac, but intact peripheral responses to orthostatic stress induced by HUT. These abnormal responses are associated with low baseline cardiac parasympathetic activity, independent of hemoglobin level. The classification of autonomic phenotypes based on HUT response may have potential use for predicting disease severity, guiding and targeting treatments/interventions to alleviate the risk of adverse outcomes in SCD. Ethics Statement All experiments were conducted at Children’s Hospital Los Angeles (CHLA). The ...
Source: Frontiers in Physiology - April 10, 2019 Category: Physiology Source Type: research

Impact of obstructive sleep apnoea and intermittent hypoxia on cardiovascular and cerebrovascular regulation
This article is protected by copyright. All rights reserved
Source: Experimental Physiology - April 1, 2017 Category: Physiology Authors: Andrew E Beaudin, Xavier Waltz, Patrick J Hanly, Marc J Poulin Tags: Review Article Source Type: research

Effects of continuous positive airway pressure and isocapnic-hypoxia on cerebral autoregulation in patients with obstructive sleep apnea.
In conclusion, CA is altered in the more severe OSA patients during normoxia but not during isocapnic-hypoxia and CPAP treatment does not impact CA. This article is protected by copyright. All rights reserved. PMID: 27644162 [PubMed - as supplied by publisher]
Source: The Journal of Physiology - September 19, 2016 Category: Physiology Authors: Waltz X, Beaudin AE, Hanly PJ, Mitsis GD, Poulin MJ Tags: J Physiol Source Type: research

Translational Approaches to Understanding Metabolic Dysfunction and Cardiovascular Consequences of Obstructive Sleep Apnea.
Abstract Obstructive Sleep Apnea (OSA) is known to be independently associated with several cardiovascular diseases including hypertension, myocardial infarction and stroke. To determine how OSA can increase cardiovascular risk, animal models have been developed to explore the underlying mechanisms and the cellular and end-organ targets of the predominant pathophysiologic disturbance in OSA - intermittent hypoxia. In spite of several limitations in translating data from animal models to the clinical arena, significant progress has been made in our understanding of how OSA confers increased cardiovascular risk. It ...
Source: American Journal of Physiology. Heart and Circulatory Physiology - July 31, 2015 Category: Physiology Authors: Drager LF, Polotsky VY, O'Donnell CP, Cravo SL, Lorenzi-Filho G, Machado BH Tags: Am J Physiol Heart Circ Physiol Source Type: research