Key result
Autonomic AF provokes mechanical alternans in single cardiomyocytes, with greater magnitude in LA versus RA.
Why the study?
Little is known about mechanical alternans in AF, and the susceptibility of different atrial regions to alternans formation remains unclear.
Does acetylcholine-CaCl2 induced atrial fibrillation cause mechanical alternans differently in left versus right atrial rat cardiomyocytes?
Does acetylcholine-CaCl2 induced atrial fibrillation cause mechanical alternans differently in left versus right atrial rat cardiomyocytes?
Left atrial cardiomyocytes show greater susceptibility to AF-induced mechanical alternans than right atrial cardiomyocytes in a rat model, potentially explaining LA mechanical dysfunction in AF.
Hypothesis-generating for LA-predominant mechanical alternans in AF; human validation required before clinical relevance.
Atrial fibrillation (AF) is the most common cardiaс arrhythmia accounting for significant morbidity and mortality. Cardiac alternans, defined at the cellular level as cyclic beat-to-beat alternations in cell contraction, action potential morphology, and intracellular Ca2+ concentration, have been associated with sustained AF. Although alternans of action potential and intracellular Ca2+ transients in atrial cardiomyocytes in AF have been elucidated, little is known about the mechanical alternans, cyclic alternations in contraction force, and cardiomyocyte shortening. Moreover, the susceptibility of different regions of atria to alternans formation is unclear. The aim of this study is to analyze and compare the parameters of alternans in sarcomere shortening-relengthening in single cardiomyocytes isolated from the left and right atria (LA, RA) of rats with acetylcholine-CaCl2 induced AF. We found that autonomic AF provoked mechanical alternans in single LA and RA cardiomyocytes. We also showed that the degree and magnitude of mechanical alternans were greater in LA cardiomyocytes than in RA cardiomyocytes. Our results propose that LA cardiomyocytes have a greater susceptibility to AF-induced beat-to-beat alternans in sarcomere shortening amplitudes than RA myocytes that may cause LA mechanical dysfunction.
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Mikhryakova et al. (2022) studied Atrial fibrillation. Left atrial (LA) cardiomyocytes vs. Right atrial (RA) cardiomyocytes was evaluated on Parameters of alternans in sarcomere shortening-relengthening. Autonomic AF provoked mechanical alternans in single cardiomyocytes, with the degree and magnitude being greater in left atrial cardiomyocytes compared to right atrial cardiomyocytes.
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