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Source: American Journal of Physiology. Heart and Circulatory Physiology

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Total 253 results found since Jan 2013.

Cardiac myosin binding protein-C phosphorylation accelerates β-cardiac myosin detachment rate in mouse myocardium
Am J Physiol Heart Circ Physiol. 2021 Mar 5. doi: 10.1152/ajpheart.00673.2020. Online ahead of print.ABSTRACTCardiac myosin binding protein-C (cMyBP-C) is a thick filament protein that modulates cardiac contraction-relaxation through its phosphorylation. Phosphorylation of cMyBP-C and ablation of cMyBP-C have been shown to increase the rate of MgADP release in the acto-myosin crossbridge cycle in the intact sarcomere. The influence of cMyBP-C on Pi-dependent myosin kinetics has not yet been examined. We investigated the effect of cMyBP-C and its phosphorylation on myosin kinetics in demembranated papillary muscle strips be...
Source: American Journal of Physiology. Heart and Circulatory Physiology - March 5, 2021 Category: Physiology Authors: Bertrand C W Tanner Michael J Previs Yuan Wang Jeffrey Robbins Bradley M Palmer Source Type: research

Hemodynamic Function of the Right Ventricular-Pulmonary Vascular-Left Atrial Unit: Normal Responses to Exercise in Healthy Adults.
Abstract With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures...
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 24, 2020 Category: Physiology Authors: Wright SP, Dawkins TG, Eves ND, Shave RE, Tedford R, Mak S Tags: Am J Physiol Heart Circ Physiol Source Type: research

Cardiovascular control during heat stress in older adults: time for an update.
The objective of this Mini-Review is to highlight these recent advances and challenge the longstanding view that the control of stroke volume during heat exposure is compromised in older adults. By doing so, our intent is to stimulate future studies to evaluate several unanswered questions in this area of research. PMID: 33275528 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 4, 2020 Category: Physiology Authors: Gravel H, Chaseling GK, Barry H, Debray A, Gagnon D Tags: Am J Physiol Heart Circ Physiol Source Type: research

Exercise physiology of the left atrium: quantity and timing of contribution to cardiac output.
This study defines the exercise behavior of the normal left atrium by quantitating its volumetric response to graded effort. Healthy subjects (n=131) were enrolled from the Health eHeart cohort. Echocardiograms were obtained at baseline and during ramped supine bicycle exercise. Left ventricular volume index, stroke volume index (LVSVI), left atrial end-systolic volume index (LAESVI), end-diastolic volume index (LAEDVI), emptying fraction (LAEF), reservoir and conduit fraction were analyzed. The LVSVI increased with low exercise, but did not increase further with peak exercise; cardiac output increased through the agency o...
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 4, 2020 Category: Physiology Authors: Bhatt A, Flink L, Lu DY, Fang Q, Bibby D, Schiller NB Tags: Am J Physiol Heart Circ Physiol Source Type: research

Exercise heat acclimation has minimal effects on left ventricular volumes, function and systemic hemodynamics in euhydrated and dehydrated trained humans.
Abstract Heat acclimation (HA) may improve the regulation of cardiac output (Q̇) through increased blood volume (BV) and left ventricular (LV) diastolic filling, and attenuate reductions in Q̇ during exercise-induced dehydration; however, these hypotheses have never been directly tested. Before and following 10-days exercise HA, eight males completed two trials of submaximal exercise in 33°C and 50% relative humidity while maintaining pre-exercise euhydrated body mass (EUH; -0.6±0.4%) or becoming progressively dehydrated (DEH; -3.6±0.7%). Rectal (Tre) and skin (Tsk) temperatures, heart rate (HR), LV volumes a...
Source: American Journal of Physiology. Heart and Circulatory Physiology - September 3, 2020 Category: Physiology Authors: Travers G, González-Alonso J, Riding NR, Nichols D, Shaw A, Periard JD Tags: Am J Physiol Heart Circ Physiol Source Type: research

Cardiac function during heat stress: Impact of short-term passive heat acclimation.
Abstract A lower heart rate (HR) during heat exposure is a classic marker of heat acclimation (HA), although it remains unclear whether this adaptation occurs secondary to reduced thermal strain and/or improvements in cardiac function. We evaluated the hypothesis that short-term passive HA reduces HR and improves cardiac function during passive heating. Echocardiography was performed under thermoneutral and hyperthermic conditions in 10 healthy adults (9 males/1 female, 29 ± 6 years old), pre and post 7 days of controlled hyperthermia. HR (P=0.61), stroke volume (P=0.99) and cardiac output (P=0.99) were similar o...
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 20, 2020 Category: Physiology Authors: Trachsel LD, Barry H, Gravel H, Behzadi P, Henri C, Gagnon D Tags: Am J Physiol Heart Circ Physiol Source Type: research

Stimulus-specific functional remodeling of the left ventricle in endurance and resistance-trained men.
In conclusion, resistance-trained individuals better maintained SV during pressure loading, whereas endurance-trained individuals demonstrated greater EDV reserve during volume loading. These data provide novel evidence of training-specific LV functional remodeling. PMID: 32772543 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 8, 2020 Category: Physiology Authors: Dawkins TG, Curry BA, Drane A, Lord RN, Richards C, Brown M, Pugh CJA, Lodge FM, Yousef Z, Stembridge M, Shave RE Tags: Am J Physiol Heart Circ Physiol Source Type: research

Synergy in the heart: RV systolic function plays a key role in optimizing LV performance during exercise.
In conclusion, this work provides mechanistic understanding of the pivotal role of the RV in optimizing LV SV during exercise. It demonstrates why optimizing RV function needs to become a key part of therapeutic strategies in patients and training for athletes. PMID: 32762556 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 6, 2020 Category: Physiology Authors: Ruijsink B, Nieves Velasco-Forte M, Duong P, Asner L, Pushparajah K, Frigiola A, Nordsletten D, Razavi R Tags: Am J Physiol Heart Circ Physiol Source Type: research

Chemogenetic activation of intracardiac cholinergic neurons improves cardiac function in pressure overload induced heart failure.
This study tests if ICG cholinergic neuron activation mitigates the progression of cardiac dysfunction and reduces mortality that occurs in HF. HF was induced by transaortic constriction (TAC) in male transgenic Long Evans rats expressing Cre recombinase within choline acetyltransferase (ChAT) neurons. ChAT neurons were selectively activated by expression and activation of excitatory Designer Receptors Exclusively Activated by Designer Receptors (DREADDs) by Clozapine-N-Oxide (TAC +Treatment & Sham Treated groups). Control animals expressed DREADDs but received saline (Sham and TAC groups). A separate set of animals we...
Source: American Journal of Physiology. Heart and Circulatory Physiology - May 14, 2020 Category: Physiology Authors: Dyavanapalli J, Hora AJ, Escobar JB, Schloen JR, Dwyer MKR, Rodriguez J, Spurney CF, Kay MW, Mendelowitz D Tags: Am J Physiol Heart Circ Physiol Source Type: research

The contribution of chymase-dependent formation of AngII to cardiac dysfunction in metabolic syndrome of young rats: roles of fructose and EETs.
In conclusions, HFD-driven adverse chymase/AngII/AT1R/Nox/superoxide signaling in young rats was prevented by inhibition of sEH via at least in part, an EET-mediated stabilization of mast cells, highlighting chymase and sEH as therapeutic targets during treatment of MetS. PMID: 32167781 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - March 12, 2020 Category: Physiology Authors: Froogh G, Kandhi S, Duvvi R, Le Y, Weng Z, Alruwaili N, Ashe JO, Sun D, Huang A Tags: Am J Physiol Heart Circ Physiol Source Type: research

Systemic and Regional Hemodynamic Response to Activation of the Exercise Pressor Reflex in Patients with Peripheral Artery Disease.
Abstract Patients with peripheral arterial disease (PAD) have an accentuated exercise pressor reflex (EPR) during exercise of the affected limb. The underlying hemodynamic changes responsible for this, and its effect on blood flow to the exercising extremity is unclear. We tested the hypothesis that the exaggerated EPR in PAD is mediated by an increase in total peripheral resistance (TPR), which augments redistribution of blood flow to the exercising limb. Eleven PAD patients and 11 age, and sex-matched subjects without PAD performed dynamic plantar flexion (PF) using the most symptomatic leg at progressive worklo...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 27, 2020 Category: Physiology Authors: Kim DJ, Kuroki MT, Cui J, Gao Z, Luck JC, Pai S, Miller AJ, Sinoway LI Tags: Am J Physiol Heart Circ Physiol Source Type: research