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European Journal of Heart Failure Sep 2022
Topics: Baroreflex; Blood Pressure; Electric Stimulation Therapy; Heart Failure; Heart Rate; Humans
PubMed: 35851979
DOI: 10.1002/ejhf.2627 -
Physiology (Bethesda, Md.) Mar 2015Because of resetting, a role for baroreflexes in long-term control of arterial pressure has been commonly dismissed in the past. However, in recent years, this... (Review)
Review
Because of resetting, a role for baroreflexes in long-term control of arterial pressure has been commonly dismissed in the past. However, in recent years, this perspective has changed. Novel approaches for determining chronic neurohormonal and cardiovascular responses to natural variations in baroreceptor activity and to electrical stimulation of the carotid baroreflex indicate incomplete resetting and sustained responses that lead to long-term alterations in sympathetic activity and arterial pressure.
Topics: Animals; Antihypertensive Agents; Arterial Pressure; Baroreflex; Cardiovascular System; Homeostasis; Humans; Hypertension; Mechanotransduction, Cellular; Models, Cardiovascular; Obesity; Pressoreceptors; Renin-Angiotensin System; Time Factors
PubMed: 25729060
DOI: 10.1152/physiol.00035.2014 -
Seminars in Reproductive Medicine Jul 2009Pregnancy is associated with dramatic alterations in maternal hemodynamics, which begin as early as 4 to 5 weeks of gestation. It has been proposed that these changes... (Review)
Review
Pregnancy is associated with dramatic alterations in maternal hemodynamics, which begin as early as 4 to 5 weeks of gestation. It has been proposed that these changes occur through autonomic control mechanisms, but the actual role of the autonomic nervous system in pregnancy is poorly understood. Here, we review what is known about the hemodynamic adaptation, changes in vascular endothelial function, sympathetic neural control and vascular responsiveness in pregnancy, and baroreflex function during pregnancy in humans. However, whether and how the sympathetic nervous system plays a role in hemodynamic homeostasis during EARLY human pregnancy remains completely unknown. Understanding the pathophysiology underlying autonomic control of maternal hemodynamics may be particularly important for prevention of cardiovascular complications during pregnancy and may improve risk stratification and prevention of cardiovascular disease for women well beyond the postpartum period.
Topics: Adaptation, Physiological; Adrenergic Fibers; Autonomic Nervous System; Baroreflex; Blood Circulation; Endothelium, Vascular; Female; Hemodynamics; Hormones; Humans; Models, Biological; Pregnancy
PubMed: 19530067
DOI: 10.1055/s-0029-1225261 -
Advances in Physiology Education Mar 2011The purpose of this brief review is to highlight key concepts about the neural control of the circulation that graduate and medical students should be expected to... (Review)
Review
The purpose of this brief review is to highlight key concepts about the neural control of the circulation that graduate and medical students should be expected to incorporate into their general knowledge of human physiology. The focus is largely on the sympathetic nerves, which have a dominant role in cardiovascular control due to their effects to increase cardiac rate and contractility, cause constriction of arteries and veins, cause release of adrenal catecholamines, and activate the renin-angiotensin-aldosterone system. These effects, as well as the control of sympathetic outflow by the vasomotor center in the medulla and the importance of sensory feedback in the form of peripheral reflexes, especially the baroreflexes, are discussed in the context of cardiovascular regulation.
Topics: Autonomic Nervous System; Baroreflex; Blood Circulation; Humans; Receptors, Adrenergic; Sympathetic Nervous System
PubMed: 21385998
DOI: 10.1152/advan.00114.2010 -
Brazilian Journal of Medical and... Sep 2002There is a close association between the location of angiotensin (Ang) receptors and many important brain nuclei involved in the regulation of the cardiovascular system.... (Review)
Review
There is a close association between the location of angiotensin (Ang) receptors and many important brain nuclei involved in the regulation of the cardiovascular system. The present review encompasses the physiological role of Ang II in the brainstem, particularly in relation to its influence on baroreflex control of the heart and kidney. Activation of AT1 receptors in the brainstem by fourth ventricle (4V) administration to conscious rabbits or local administration of Ang II into the rostral ventrolateral medulla (RVLM) of anesthetized rabbits acutely increases renal sympathetic nerve activity (RSNA) and RSNA baroreflex responses. Administration of the Ang antagonist Sarile into the RVLM of anesthetized rabbits blocked the effects of Ang II on the RSNA baroreflex, indicating that the RVLM is the major site of sympathoexcitatory action of Ang II given into the cerebrospinal fluid surrounding the brainstem. However, in conscious animals, blockade of endogenous Ang receptors in the brainstem by the 4V AT1 receptor antagonist losartan resulted in sympathoexcitation, suggesting an overall greater activity of endogenous Ang II within the sympathoinhibitory pathways. However, the RSNA response to airjet stress in conscious rabbits was markedly attenuated. While we found no effect of acute central Ang on heart rate baroreflexes, chronic 4V infusion inhibited the baroreflex and chronic losartan increased baroreflex gain. Thus, brainstem Ang II acutely alters sympathetic responses to specific afferent inputs thus forming part of a potentially important mechanism for the integration of autonomic response patterns. The sympathoexcitatory AT1 receptors appear to be activated during stress, surgery and anesthesia.
Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Baroreflex; Blood Circulation; Blood Pressure; Brain Stem; Kidney; Losartan; Medulla Oblongata; Rabbits; Rats; Receptor, Angiotensin, Type 1; Sympathetic Nervous System
PubMed: 12219176
DOI: 10.1590/s0100-879x2002000900005 -
American Journal of Physiology.... Apr 2005Recent findings in chronically instrumented animals challenge the classic concept that baroreflexes do not play a role in the chronic regulation of arterial pressure. As... (Review)
Review
Recent findings in chronically instrumented animals challenge the classic concept that baroreflexes do not play a role in the chronic regulation of arterial pressure. As alterations in renal excretory function are of paramount importance in the chronic regulation of arterial pressure, several of these recent studies have focused on the long-term interactions between the baroreflex and the kidneys during chronic perturbations in arterial pressure and body fluid volumes. An emerging body of evidence indicates that the baroreflex is chronically activated in several experimental models of hypertension, but in most cases, the duration of these studies has not exceeded 2 wk. Although these studies suggest that the baroreflex may play a compensatory role in attenuating the severity of the hypertension, possibly even in primary hypertension with uncertain causes of sympathetic activation, there has been only limited assessment of the quantitative importance of this interaction in the regulation of arterial pressure. In experimental models of secondary hypertension, baroreflex suppression of renal sympathetic nerve activity is sustained and chronically promotes sodium excretion. This raises the possibility that the renal nerves may be the critical efferent link for baroreceptor-induced suppression of central sympathetic output through which long-term compensatory reductions in arterial pressure are produced. This contention is supported by strong theoretical evidence but must be corroborated by experimental studies. Finally, although it is now clear that pressure-induced increases in baroreflex activity persist for longer periods of time than previously suggested, studies using new tools and novel approaches and extending beyond 2 wk of hypertension are needed to elucidate the true role of the baroreflex in the pathogenesis of clinical hypertension.
Topics: Angiotensin II; Animals; Baroreflex; Blood Pressure; Denervation; Humans; Hypertension, Renal; Kidney; Neurons; Sinoatrial Node; Sodium
PubMed: 15793036
DOI: 10.1152/ajpregu.00591.2004 -
Natriuretic Peptides-New Targets for Neurocontrol of Blood Pressure via Baroreflex Afferent Pathway.International Journal of Molecular... Nov 2022Natriuretic peptides (NPs) induce vasodilation, natriuresis, and diuresis, counteract the renin-angiotensin-aldosterone system and autonomic nervous system, and are key...
Natriuretic peptides (NPs) induce vasodilation, natriuresis, and diuresis, counteract the renin-angiotensin-aldosterone system and autonomic nervous system, and are key regulators of cardiovascular volume and pressure homeostasis. Baroreflex afferent pathway is an important reflex loop in the neuroregulation of blood pressure (BP), including nodose ganglion (NG) and nucleus tractus solitarius (NTS). Dysfunction of baroreflex would lead to various hypertensions. Here, we carried out functional experiments to explore the effects of NPs on baroreflex afferent function. Under physiological and hypertensive condition (high-fructose drinking-induced hypertension, HFD), BP was reduced by NPs through NG microinjection and baroreflex sensitivity (BRS) was enhanced via acute intravenous NPs injection. These anti-hypertensive effects were more obvious in female rats with the higher expression of NPs and its receptor A/B (NPRA/NPRB) and lower expression of its receptor C (NPRC). However, these effects were not as obvious as those in HFD rats compared with the same gender control group, which is likely to be explained by the abnormal expression of NPs and NPRs in the hypertensive condition. Our data provide additional evidence showing that NPs play a crucial role in neurocontrol of BP regulation via baroreflex afferent function and may be potential targets for clinical management of metabolic-related hypertension.
Topics: Female; Animals; Rats; Baroreflex; Blood Pressure; Rats, Sprague-Dawley; Afferent Pathways; Hypertension; Natriuretic Peptides
PubMed: 36362405
DOI: 10.3390/ijms232113619 -
Comprehensive Physiology Jan 2015Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially... (Review)
Review
Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur.
Topics: Baroreflex; Cardiovascular System; Cerebrovascular Circulation; Heat Stress Disorders; Hemodynamics; Humans; Muscle, Skeletal; Renal Circulation; Splanchnic Circulation
PubMed: 25589263
DOI: 10.1002/cphy.c140015 -
International Heart Journal 2016Circulatory homeostasis is associated with interactions between multiple organs, and the disruption of dynamic circulatory homeostasis could be considered as heart... (Review)
Review
Circulatory homeostasis is associated with interactions between multiple organs, and the disruption of dynamic circulatory homeostasis could be considered as heart failure. The brain is the central unit integrating neural and neurohormonal information from peripheral organs and controlling peripheral organs using the autonomic nervous system. Heart failure is worsened by abnormal sympathoexcitation associated with baroreflex failure and/or chemoreflex activation, and by vagal withdrawal, and autonomic modulation therapies have benefits for heart failure. Recently, we showed that baroreflex failure induces striking volume intolerance independent of left ventricular dysfunction. Many studies have indicated that an overactive renin-angiotensin system, excess oxidative stress and excess inflammation, and/or decreased nitric oxide in the brain cause sympathoexcitation in heart failure. We have demonstrated that angiotensin II type 1 receptor (AT1R)-induced oxidative stress in the rostral ventrolateral medulla (RVLM), which is known as a vasomotor center, causes prominent sympathoexcitation in heart failure model rats. Interestingly, systemic infusion of angiotensin II directly affects brain AT1R with sympathoexcitation and left ventricular diastolic dysfunction. Moreover, we have demonstrated that targeted deletion of AT1R in astrocytes strikingly improved survival with prevention of left ventricular remodeling and sympathoinhibition in myocardial infarction-induced heart failure. From these results, we believe it is possible that AT1R in astrocytes, not in neurons, have a key role in the pathophysiology of heart failure. We would like to propose a novel concept that the brain works as a central processing unit integrating neural and hormonal input, and that the disruption of dynamic circulatory homeostasis mediated by the brain causes heart failure.
Topics: Animals; Baroreflex; Brain; Cerebrovascular Circulation; Heart Failure; Homeostasis; Humans; Renin-Angiotensin System; Sympathetic Nervous System
PubMed: 26973279
DOI: 10.1536/ihj.15-517 -
Acta Pharmacologica Sinica Aug 2002Arterial baroreflex (ABR) is a very important mechanism in the regulation of cardiovascular activities. As ABR function is largely inhibited by anesthesia, its... (Review)
Review
Arterial baroreflex (ABR) is a very important mechanism in the regulation of cardiovascular activities. As ABR function is largely inhibited by anesthesia, its measurement in conscious animal becomes important. The present review summarizes the works concerning ABR function in conscious rats completed in our department in the last 10 years. Firstly, a new method was established to measure arterial baroreflex-blood pressure control (ABR-BP). ABR-BP and baroreflex sensitivity measured with classic method are two different parts of the ABR function. Secondly, it was proposed that ABR function predicted the end-organ damage in hypertension. Thirdly, interruption of ABR induced severe end-organ damages. Increased blood pressure variability (BPV) and activation of renin angiotensin system were involved in the mechanisms underlying organ damages in sinoaortic denervation (SAD) rats. Fourthly, we propose that amelioration of ABR function may serve as a new strategy for improving the prognosis of cardiovascular diseases. Ketanserin improved the impaired ABR function in SHR. Finally, the possibility to develop a strain of rats with spontaneous deficiency on ABR function is mentioned.
Topics: Animals; Aorta; Baroreflex; Blood Pressure; Denervation; Hypertension; Ketanserin; Rats; Rats, Inbred SHR; Sinoatrial Node
PubMed: 12147187
DOI: No ID Found