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Hypertension (Dallas, Tex. : 1979) Jan 2022
Topics: Baroreflex; Blood Pressure; Pressoreceptors
PubMed: 34878899
DOI: 10.1161/HYPERTENSIONAHA.121.18372 -
JACC. Clinical Electrophysiology Feb 2022This study sought to evaluate the role of cardiac afferent reflexes in atrial fibrillation (AF).
OBJECTIVES
This study sought to evaluate the role of cardiac afferent reflexes in atrial fibrillation (AF).
BACKGROUND
Efferent autonomic tone is not associated with atrial remodeling and AF persistence. However, the role of cardiac afferents is unknown.
METHODS
Individuals with nonpermanent AF (n = 48) were prospectively studied (23 in the in-AF group and 25 in sinus rhythm [SR]) with 12 matched control subjects. We performed: 1) low-level lower body negative pressure (LBNP), which decreases cardiac volume, offloading predominantly cardiac afferent (volume-sensitive) low-pressure baroreceptors; 2) Valsalva reflex (predominantly arterial high-pressure baroreceptors); and 3) isometric handgrip reflex (both baroreceptors). We measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR). LBNP elicits reflex vasoconstriction, estimated using venous occlusion plethysmography-derived forearm blood flow (∝1/vascular resistance), maintaining MAP. To assess reversibility, we repeated LBNP (same day) after 1-hour low-level tragus stimulation (in n = 5 in the in-AF group and n = 10 in the in-SR group) and >6 weeks post-cardioversion (n = 7).
RESULTS
The 3 groups were well matched for age (59 ± 12 years, 83% male), body mass index, and risk factors (P = NS). The in-AF group had higher left atrial volume (P < 0.001) and resting HR (P = 0.01) but similar MAP (P = 0.7). The normal LBNP vasoconstriction (-49 ± 5%) maintaining MAP (control subjects) was attenuated in the in-SR group (-12 ± 9%; P = 0.005) and dysfunctional in the in-AF group (+11 ± 6%; P < 0.001), in which MAP decreased and HR was unchanged. Valsalva was normal throughout. Handgrip MAP response was lowest in the in-AF group (P = 0.01). Interestingly, low-level tragus stimulation and cardioversion improved LBNP vasoconstriction (-48 ± 15%; P = 0.04; and -32 ± 9%; P = 0.02, respectively).
CONCLUSIONS
Cardiac afferent (volume-sensitive) reflexes are abnormal in AF patients during SR and dysfunctional during AF. This could contribute to AF progression, thus explaining "AF begets AF." (Characterisation of Autonomic function in Atrial Fibrillation [AF-AF Study]; ACTRN12619000186156).
Topics: Aged; Atrial Fibrillation; Female; Hand Strength; Heart Atria; Humans; Lower Body Negative Pressure; Male; Middle Aged; Pressoreceptors
PubMed: 35210071
DOI: 10.1016/j.jacep.2021.10.010 -
Nutrients Feb 2022For normal maintenance of blood pressure and blood volume a well-balanced renin-angiotensin-aldosterone system (RAS) is necessary. For this purpose, renin is secreted as... (Review)
Review
For normal maintenance of blood pressure and blood volume a well-balanced renin-angiotensin-aldosterone system (RAS) is necessary. For this purpose, renin is secreted as the situation demands by the juxtaglomerular cells (also called as granular cells) that are in the walls of the afferent arterioles. Juxtaglomerular cells can sense minute changes in the blood pressure and blood volume and accordingly synthesize, store, and secrete appropriate amounts of renin. Thus, when the blood pressure and blood volume are decreased JGA cells synthesize and secrete higher amounts of renin and when the blood pressure and blood volume is increased the synthesis and secretion of renin is decreased such that homeostasis is restored. To decipher this important function, JGA cells (renin cells) need to sense and transmit the extracellular physical forces to their chromatin to control renin gene expression for appropriate renin synthesis. The changes in perfusion pressure are sensed by Integrin β1 that is transmitted to the renin cell's nucleus via lamin A/C that produces changes in the architecture of the chromatin. This results in an alteration (either increase or decrease) in renin gene expression. Cell membrane is situated in an unique location since all stimuli need to be transmitted to the cell nucleus and messages from the DNA to the cell external environment can be conveyed only through it. This implies that cell membrane structure and integrity is essential for all cellular functions. Cell membrane is composed to proteins and lipids. The lipid components of the cell membrane regulate its (cell membrane) fluidity and the way the messages are transmitted between the cell and its environment. Of all the lipids present in the membrane, arachidonic acid (AA) forms an important constituent. In response to pressure and other stimuli, cellular and nuclear shape changes occur that render nucleus to act as an elastic mechanotransducer that produces not only changes in cell shape but also in its dynamic behavior. Cell shape changes in response to external pressure(s) result(s) in the activation of cPLA2 (cytosolic phospholipase 2)-AA pathway that stretches to recruit myosin II which produces actin-myosin cytoskeleton contractility. Released AA can undergo peroxidation and peroxidized AA binds to DNA to regulate the expression of several genes. Alterations in the perfusion pressure in the afferent arterioles produces parallel changes in the renin cell membrane leading to changes in renin release. AA and its metabolic products regulate not only the release of renin but also changes in the vanilloid type 1 (TRPV1) expression in renal sensory nerves. Thus, AA and its metabolites function as intermediate/mediator molecules in transducing changes in perfusion and mechanical pressures that involves nuclear mechanotransduction mechanism. This mechanotransducer function of AA has relevance to the synthesis and release of insulin, neurotransmitters, and other soluble mediators release by specialized and non-specialized cells. Thus, AA plays a critical role in diseases such as diabetes mellitus, hypertension, atherosclerosis, coronary heart disease, sepsis, lupus, rheumatoid arthritis, and cancer.
Topics: Arachidonic Acid; Juxtaglomerular Apparatus; Mechanotransduction, Cellular; Pressoreceptors; Renin
PubMed: 35215399
DOI: 10.3390/nu14040749 -
Trends in Cardiovascular Medicine Oct 2020Atrial fibrillation (AF) is a rapidly growing clinical problem in routine practice, both for cardiologists as well as general practitioners. Current therapies aimed at... (Review)
Review
Atrial fibrillation (AF) is a rapidly growing clinical problem in routine practice, both for cardiologists as well as general practitioners. Current therapies aimed at the management of AF include anti-arrhythmic drug therapy and catheter ablation. These therapies have a number of limitations and risks, and have disappointing long-term efficacy in maintaining sinus rhythm and improving hard clinical outcomes. Because of this, there is growing interest in pursuing alternative management strategies in patients with AF. This review seeks to highlight emerging AF therapies, with a specific focus on several modalities aimed at modulation of the autonomic nervous system. These therapies have shown promise in early pre-clinical and clinical trials, and represent exciting alternatives to standard AF treatment.
Topics: Animals; Atrial Fibrillation; Autonomic Nervous System; Baroreflex; Heart Atria; Heart Rate; Humans; Kidney; Magnetic Field Therapy; Pressoreceptors; Recovery of Function; Renal Artery; Sympathectomy; Treatment Outcome; Vagus Nerve Stimulation
PubMed: 31708408
DOI: 10.1016/j.tcm.2019.10.009 -
Advances in Physiology Education Jun 2022While the effects of changing heart rate and systemic vascular resistance have been generally understood and appreciated, the effects of changes in left ventricular... (Review)
Review
While the effects of changing heart rate and systemic vascular resistance have been generally understood and appreciated, the effects of changes in left ventricular contractility on end-systolic volume may have been less understood and appreciated and the effects of changes in venous capacitance on end-diastolic volume may have been unknown to many readers. Herein, we have provided a brief review for the medical student and beginning graduate student highlighting these sometimes-complex relationships.
Topics: Blood Pressure; Heart Rate; Heart Ventricles; Humans; Pressoreceptors; Vascular Resistance
PubMed: 35201919
DOI: 10.1152/advan.00160.2021 -
Hypertension (Dallas, Tex. : 1979) May 2023
Topics: Humans; Baroreflex; COVID-19; Pressoreceptors; Sympathetic Nervous System; Blood Pressure; Afferent Pathways
PubMed: 36802914
DOI: 10.1161/HYPERTENSIONAHA.123.20316 -
Lin Chuang Er Bi Yan Hou Tou Jing Wai... Nov 2021With the continuous updating of head and neck surgery concepts and techniques, more and more head and neck surgeries are developing in the direction of... (Review)
Review
With the continuous updating of head and neck surgery concepts and techniques, more and more head and neck surgeries are developing in the direction of refinement.however, the more complete the surgery, the greater the possibility of subsequent nerve exposure and injury. Even a slight perturbation of the nerve may cause serious complications, such as pressure receptor failure.It is necessary to review the mechanisms and the characteristics of baroreceptor failure syndrome after head and neck tumor surgery.
Topics: Head; Head and Neck Neoplasms; Humans; Neck; Postoperative Complications; Pressoreceptors
PubMed: 34886615
DOI: 10.13201/j.issn.2096-7993.2021.11.020 -
The Canadian Journal of Cardiology May 2020The sympathetic nervous system plays a pivotal role in the long-term regulation of arterial blood pressure through the ability of the central nervous system to integrate... (Review)
Review
The sympathetic nervous system plays a pivotal role in the long-term regulation of arterial blood pressure through the ability of the central nervous system to integrate neurohumoral signals and differentially regulate sympathetic neural input to specific end organs. Part 1 of this review will discuss neural mechanisms of salt-sensitive hypertension, obesity-induced hypertension, and the ability of prior experiences to sensitize autonomic networks. Part 2 of this review focuses on new therapeutic advances to treat resistant hypertension including renal denervation and carotid baroactivation. Both advances lower arterial blood pressure by reducing sympathetic outflow. We discuss potential mechanisms and areas of future investigation to target the sympathetic nervous system.
Topics: Animals; Autonomic Pathways; Baroreflex; Humans; Hypertension; Kidney; Obesity; Pressoreceptors; Sodium, Dietary; Sympathectomy; Sympathetic Nervous System
PubMed: 32389344
DOI: 10.1016/j.cjca.2020.03.003 -
Circulation. Arrhythmia and... Apr 2021Symptomatic heart failure (HF) patients despite optimal medical therapy and advances such as invasive hemodynamic monitoring remain challenging to manage. While cardiac... (Review)
Review
Symptomatic heart failure (HF) patients despite optimal medical therapy and advances such as invasive hemodynamic monitoring remain challenging to manage. While cardiac resynchronization therapy remains a highly effective therapy for a subset of HF patients with wide QRS, a majority of symptomatic HF patients are poor candidates for such. Recently, cardiac contractility modulation, neuromodulation based on carotid baroreceptor stimulation, and phrenic nerve stimulation have been approved by the US Food and Drug Administration and are emerging as therapeutic options for symptomatic HF patients. This state-of-the-art review examines the role of these evolving electrical therapies in advanced HF.
Topics: Animals; Autonomic Nervous System; Cardiac Pacing, Artificial; Electric Stimulation Therapy; Heart; Heart Failure; Humans; Myocardial Contraction; Pacemaker, Artificial; Prevalence; Recovery of Function; Spinal Cord Stimulation; Stroke Volume; Treatment Outcome; Vagus Nerve Stimulation; Ventricular Function, Left
PubMed: 33858178
DOI: 10.1161/CIRCEP.120.009668 -
Cell Reports Nov 2019Soohong et al. (2019) reveal a class of vagal afferents-defined by Piezo2 expression-that innervate the aorta and function to sense blood pressure fluctuations. Their...
Soohong et al. (2019) reveal a class of vagal afferents-defined by Piezo2 expression-that innervate the aorta and function to sense blood pressure fluctuations. Their study describes the morphologies and role of these neurons in vascular regulation.
Topics: Animals; Aorta; Baroreflex; Blood Pressure; Hoof and Claw; Pressoreceptors
PubMed: 31747586
DOI: 10.1016/j.celrep.2019.11.031