Exercise and calcium in the heart

Abstract

Cardiomyocyte Ca2+ dictates cardiac contraction, via excitation-contraction coupling and excitation-transcription coupling. Adaptation to these processes also majorly contributes to enhanced contractile function and capacity following exercise training. Cytoplasmic Ca2+ release controls sarcomeric contraction, with important modulation by the voltage-sensitive plasma membrane L-type Ca2+ channel and the Ryanodine receptor, as well as the Sarcoplasmic reticulum Ca2+ ATPase. Exercise training increases and enhances these excitation-contraction coupling sub-processes, in a manner that increases and enhances cardiac contraction. Also, adaptation to exercise training further includes myofilament Ca2+ sensitization. Then there are several aspects linked to post-exercise training cardiomyocyte Ca2+ handling that remain speculative and inconclusive, but could if proven true be of special importance. This includes Ca2+-linked muscle-specific gene transcription to alter cell architecture and size, and it includes the scenario whereby Ca2+ cycling and adaptations may alter arrhythmogenicity. These aspects of cardiac Ca2+ adaptations to exercise training are discussed in this review article.