Abstract
Each cardiac myocyte fires an action potential (AP) due to excitation propagated from the sinoatrial node to elicit cardiac muscle contraction by a mechanism, known as excitation–contraction coupling. Cardiac contractility is regulated by the changes in intracellular free Ca2+ [Ca2+]i concentration and physiological function requires that [Ca2+]i should be sufficiently high in systole and low in diastole. Ca2+ needed for contraction comes mainly from the sarcoplasmic reticulum (SR) and is released by the process of calcium-induced calcium release. The mechanisms that enhance [Ca2+]i increase the amount of ATP hydrolyzed and the force generated by the actin and myosin interactions, including the velocity of shortening. Physiologically, [Ca2+]i is influenced primarily by beta-adrenoceptor-coupled mechanisms. During the initiation of cardiac contraction, the cardiac dyad is a specialized signaling communication concerned primarily with the clusters of L-type Ca2+ channels (LTCCs) on the sarcolemma closely apposed (≈15nm) across the dyadic cleft to clusters of ryanodine receptors on the SR membrane. The cardiac dyad contains additional structures that may contribute to the modulation of Ca2+ release from the SR during systole. Extensively studies demonstrated that Na+-Ca2+-exchange, via its reverse-mode action, can contribute to Ca2+ influx early during the AP. As such, an increase in LTCCs may indicate that influx of Ca2+ is greater than efflux. This increases the amount of Ca2+ in the cell and SR until the resulting increase of the amplitude of the Ca2+ transient increases efflux to a level that restores flux balance. This review is related to the molecular changes occurring in cardiac calcium homeostasis in health and disease.
Original language | English |
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Title of host publication | Pathophysiology, Risk Factors, and Management of Chronic Heart Failure |
Publisher | Elsevier |
Pages | 149-158 |
Number of pages | 10 |
ISBN (Electronic) | 9780128229729 |
ISBN (Print) | 9780128231111 |
DOIs | |
Publication status | Published - Jan 1 2024 |
Keywords
- action potential
- calcium
- Cardiac muscle
- excitation–contraction coupling
- repolarization
ASJC Scopus subject areas
- General Agricultural and Biological Sciences
- General Biochemistry,Genetics and Molecular Biology