The heart of hibernating mammals is known to demonstrate the nature\'s model of resistance to rhythm disturbances, including ventricular arrhythmias, during hypothermia. However, electrophysiological mechanism of this phenomenon is not completely understood. Using optical mapping technique with voltage-sensitive dye di-4-ANEPPS, we investigated the spatiotemporal characteristics of ventricular activation in Langendorff-perfused hearts of winter hibernating ground squirrels Spermophyllus undulatus and rabbits at temperatures from +37 degrees C to +3 degrees C. In rabbit hearts, reduction of temperature from 37 to 17 degrees C resulted in significant decrease of conduction velocity and increase of conduction anisotropy. Excitation failure was observed in the rabbit heart at 12+/-1 degree C. In contrast, ground squirrels exhibited significantly faster conduction velocity compared with rabbits at all temperatures and insensibility of conduction anisotropy to cooling down to 3C which can protect the hibernator heart against arrhythmias during hypothermia.
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Prog Cardiovasc Dis
January 2025
Division of Cardiovascular Medicine, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA. Electronic address:
Myocardial viability assessment is used to determine if chronically dysfunctional myocardium may benefit from coronary revascularization. Cardiac magnetic resonance with late gadolinium enhancement is the current gold standard for visualizing myocardial scar and provides valuable insight into myocardial viability. Viability assessments can also be made with Cardiac Positron Emission Tomography, Echocardiography, Single Photon Emission Tomography, and Cardiac Computed Tomography with each having advantages and disadvantages.
View Article and Find Full Text PDFJ Vet Med Sci
December 2024
Laboratory of Veterinary Physiology, Faculty of Applied Biological Sciences, Gifu University.
Mol Metab
December 2024
Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Myocardial Homeostasis and Cardiac Injury Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain. Electronic address:
Aim: The aim of the present study was to define whether cardiac myosin contributes to energy conservation in the heart of hibernating mammals.
Methods: Thin cardiac strips were isolated from the left ventricles of active and hibernating grizzly bears; and subjected to loaded Mant-ATP chase assays, X-ray diffraction and proteomics.
Main Findings: Hibernating grizzly bears displayed an unusually high proportion of ATP-conserving super-relaxed cardiac myosin molecules that are likely due to altered levels of phosphorylation and rod region stability.
Cureus
November 2024
Internal Medicine Department, Shalamar Hospital, Lahore, PAK.
Introduction: Acute anterior wall myocardial infarction (AWMI), when presenting with ST-segment elevation on an electrocardiogram (ECG), represents a form of ST-elevation myocardial infarction (STEMI) caused by a significant reduction in coronary blood flow to the heart muscle. The shape of the ST-segment elevation, whether it is concave, convex, or straight, has been associated with different levels of left ventricular ejection fraction (LVEF), which is an important indicator of cardiac function and prognosis.
Objective: To investigate the relationship between the type of ST-segment elevation on ECG and LVEF measured 48 hours after the onset of myocardial infarction in patients with AWMI.
Torpor is a state used by several mammals to survive harsh winters and avoid predation, characterized by a drastic reduction in metabolic rate followed by a decrease in body temperature, heart rate, and many physiological variables. During torpor, all organs and systems must adapt to the new low-energy expenditure conditions to preserve physiological homeostasis. These adaptations may be exploited in a translational perspective in several fields.
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