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Circulation Journal : Official Journal... 2015
Topics: Animals; Baroreflex; Hypertension; Male; Pressoreceptors
PubMed: 25746529
DOI: 10.1253/circj.CJ-15-0084 -
Journal of Cardiovascular Translational... Apr 2014Sympathoactivation is a prominent feature of heart failure (HF). Its role in cardiac remodeling and arrhythmogenesis is well-recognized today, although incomplete... (Review)
Review
Sympathoactivation is a prominent feature of heart failure (HF). Its role in cardiac remodeling and arrhythmogenesis is well-recognized today, although incomplete understanding of autonomic mechanisms was a barrier to development of contemporary medical therapies. Despite widespread availability of drugs and devices, mortality and morbidity in HF remain unacceptably high. Recognition of an additional phenotype, HF with preserved ejection fraction (EF), poses additional challenges. New treatment options are required. Electrical modulation of the central nervous system with baroreflex activation therapy offers a new approach. Activation of this afferent pathway induces the central nervous system to rebalance autonomic modulation of the cardiovascular system. Results in animal models of HF demonstrating increased survival and beneficial cardiac remodeling recently led to a clinical feasibility study in HF with reduced EF wherein the clinical course of patients dramatically improved. Results in resistant hypertension patients further suggest potential for benefit in HF with preserved EF.
Topics: Animals; Autonomic Nervous System; Disease Models, Animal; Heart Failure; Heart-Assist Devices; Humans; Pressoreceptors; Ventricular Remodeling
PubMed: 24563340
DOI: 10.1007/s12265-014-9546-8 -
Acta Physiologica Polonica 1968
Topics: Animals; Carotid Sinus; Chemoreceptor Cells; Electrophysiology; Pressoreceptors; Rabbits; Respiration
PubMed: 5670303
DOI: No ID Found -
Biological Reviews of the Cambridge... May 1985
Review
Topics: Alligators and Crocodiles; Amphibians; Animals; Anura; Biological Evolution; Birds; Blood Pressure; Cardiovascular System; Fishes; Humans; Invertebrates; Lizards; Mammals; Physiology; Pressoreceptors; Reptiles; Snakes; Urodela
PubMed: 3890977
DOI: 10.1111/j.1469-185x.1985.tb00713.x -
Archivos Del Instituto de Cardiologia... Feb 1951
Topics: Carotid Sinus; Heart Rate; Humans; Myocardial Contraction; Pressoreceptors
PubMed: 14847870
DOI: No ID Found -
Fundamental & Clinical Pharmacology 1987The arterial baroreceptor reflex (BR; aortic and carotid sinus BR) and the cardiopulmonary BR are the most important reflexes acting as buffer systems for the... (Review)
Review
The arterial baroreceptor reflex (BR; aortic and carotid sinus BR) and the cardiopulmonary BR are the most important reflexes acting as buffer systems for the maintenance of arterial pressure around a fixed physiologic value. They act as permanent inhibitory systems on the central cardiovascular structures and they can be either activated or deactivated by using selective techniques. During chronic hypertension there are structural alterations of the peripheral and/or central components of the BR that become "reset", with a shift in the function curve relating BR activity to blood pressure (BP) in the direction of higher pressure values. As a consequence of the hypertension-induced resetting phenomenon, both the threshold pressure and sensitivity of BR are disturbed. However, if BR resetting during hypertension clearly decreases the sensitivity of BR control of heart rate (HR), BR control of peripheral resistance and arterial pressure as a whole is preserved and even increased when hypertension develops. Thus, this apparent discrepancy between BR control of HR and BP during hypertension demonstrates that evaluation of an antihypertensive therapy on reflex control of HR alone cannot predict what will happen to BR control of the whole cardiovascular system. Regarding BR control of HR, in contrast to the classical arteriolar vasodilators such as hydralazine and its derivatives, the majority of the modern antihypertensive drugs do not evoke reflex tachycardia in response to lowering of BP in normotensive or hypertensive subjects. Although the intrinsic pharmacologic mechanisms of action of these drugs on BR may be quite different (e.g., alpha 1-or beta-adrenoreceptor blocking agents, converting enzyme inhibitors, certain calcium-channel blockers of the phenyldihydropyridine group, and so on), they all shift in a parallel manner the set-point of the BR response curve towards lower pressures, with no change in HR or R-R interval. Generally, this resetting phenomenon occurs after several weeks or months of antihypertensive therapy, but it can also occur acutely (e.g. after IV injection) after administration of drugs such as prazosin or ketanserin. Finally, antihypertensive agents such as clonidine and methyldopa can simultaneously reset the BR and increase its sensitivity, thus leading to almost complete restoration of control of HR response despite the concomitant decrease in BP. Regarding BR control of blood pressure, only captopril and especially celiprolol (a beta 1-adrenoreceptor blocking drug with vasodilating properties) are able to restore almost normal BR control of arterial pressure.
Topics: Antihypertensive Agents; Blood Pressure; Carotid Sinus; Efferent Pathways; Heart Rate; Humans; Hypertension; Pressoreceptors; Reflex
PubMed: 3325391
DOI: 10.1111/j.1472-8206.1987.tb00565.x -
Indian Journal of Physiology and... Apr 2003The role of cardiovascular receptors in the neural regulation of circulatory system is now well established. Atrial type B receptors located in the two atria and... (Review)
Review
The role of cardiovascular receptors in the neural regulation of circulatory system is now well established. Atrial type B receptors located in the two atria and veno-atrial junctions, which are stimulated by atrial filling are believed to play an important role in the regulation of body fluid volume and heart rate. Heart rate is influenced also by other sensory receptors e.g. arterial baroreceptors, ventricular receptors, pulmonary stretch receptors and chemoreceptors. Of all these visceral receptors, arterial baroreceptors located mainly in the aortic arch and the carotid sinus region are stimulated by intravascular pressure; play a major role in the regulation of blood pressure by changes in heart rate and vascular tone. The vascular tone is also affected by the circulatory levels of various neurotransmitters and hormones. Vasodilatory response to adenosine and acetylcholine is partly mediated through endothelium-derived relaxing factors (EDRF), hyperpolarizing factors (EDHF) and contracting factors (EDCF). The endothelium-dependent mechanisms are altered during hypertension and diabetes. The autonomic control of blood pressure is primarily through arterial baroreceptors. The sensitivity of the baroreceptor heart rate reflex is significantly attenuated on occlusion of left anterior descending coronary artery (LAD) of anaesthetised dogs taken as an experimental model of coronary insufficiency in-patients of coronary heart disease. The fall in the sensitivity of baroreflex on LAD occlusion is mediated primarily by sympathetic limb of the autonomic nervous system. Acute fall in hemoglobin level by hemodilution in dogs produced an increase in cardiac output by increasing the heart rate through inhibition of parasympathetic tone. After parasympathetic blockade the increase in cardiac output on fall in hemoglobin was due to a rise in the stroke volume. Acute fall in hemoglobin level attenuated the baroreflex response. Sustained changes in blood pressure cause resetting of baroreflex i.e. increase in arterial pressure involves reduced activity of baroreceptors at equivalent pressure and vascular stretch. Like in acute hypoxia the altered responsiveness of baroreceptor heart rate reflex during oxygen deficiency due to acute occlusion of LAD or acute normovolemic hemodilution may involve both peripheral and central components and possibility of modulation by circulating hormones also exists.
Topics: Animals; Blood Pressure; Heart; Heart Rate; Humans; Pressoreceptors
PubMed: 15255616
DOI: No ID Found -
Journal of the American College of... Oct 2006
Topics: Baroreflex; Cardiovascular System; Fatty Acids, Unsaturated; Heart Failure; Humans; Myocardial Infarction; Pressoreceptors
PubMed: 17045895
DOI: 10.1016/j.jacc.2006.07.029 -
Brain Research Bulletin Jan 2000The fundamental neuronal substrates of the arterial baroreceptor reflex have been elucidated by combining anatomical, neurophysiological, and pharmacological approaches.... (Review)
Review
The fundamental neuronal substrates of the arterial baroreceptor reflex have been elucidated by combining anatomical, neurophysiological, and pharmacological approaches. A serial pathway between neurons located in the nuclei of the solitary tract (NTS), the caudal ventrolateral medulla (CVL), and the rostral ventrolateral medulla (RVL) plays a critical role in inhibition of sympathetic outflow following stimulation of baroreceptor afferents. In this paper, we summarize our studies using tract-tracing and electron microscopic immunocytochemistry to define the potential functional sites for synaptic transmission within this circuitry. The results are discussed as they relate to the literature showing: (1) baroreceptor afferents excite second-order neurons in NTS through the release of glutamate; (2) these NTS neurons in turn send excitatory projections to neurons in the CVL; (3) GABAergic CVL neurons directly inhibit RVL sympathoexcitatory neurons; and (4) activation of this NTS-->CVL-->RVL pathway leads to disfacilitation of sympathetic preganglionic neurons by promoting withdrawal of their tonic excitatory drive, which largely arises from neurons in the RVL. Baroreceptor control may also be regulated over direct reticulospinal pathways exemplified by a newly recognized sympathoinhibitory region of the medulla, the gigantocellular depressor area. This important autonomic reflex may also be influenced by parallel, multiple, and redundant networks.
Topics: Animals; Baroreflex; Medulla Oblongata; Neural Inhibition; Neural Pathways; Neurons; Pressoreceptors; Rats; Sympathetic Nervous System
PubMed: 10709955
DOI: 10.1016/s0361-9230(99)00233-6 -
Experimental Physiology Jul 2004The current consensus is that arterial baroreceptors are vitally important in the short term (seconds to minutes) control of mean arterial pressure (MAP) but are... (Review)
Review
The current consensus is that arterial baroreceptors are vitally important in the short term (seconds to minutes) control of mean arterial pressure (MAP) but are unimportant in determining the long-term level of MAP. The latter statement is based primarily on two observations: first, that baroreceptors rapidly reset to the prevailing level of MAP and second, that total baroreceptor denervation has no lasting effect on the average daily MAP, although the variability of MAP is increased dramatically. However, recent studies in intact experimental animals have produced results that suggest baroreceptor resetting may not be as rapid or complete as previously thought. Furthermore, reconsideration of the responses to baroreceptor denervation suggest that the condition may accurately represent responses to short-term baroreceptor unloading but not long-term unloading. Results obtained using a new model of chronic baroreceptor unloading indicate that the condition results in a sustained increase in MAP. These results strongly suggest that the role of baroreceptors in the long term control of MAP needs to be revisited.
Topics: Animals; Blood Pressure; Humans; Pressoreceptors; Time Factors
PubMed: 15131071
DOI: 10.1113/expphysiol.2004.027441