Key result
Evidence from the literature suggests that mechanical restitution begins with sarcolemma repolarization, compatible with a sarcolemmal source of trigger calcium in myocardial cells.
This review proposes that the trigger for calcium-induced calcium release in myocardial cells may originate from a sarcolemmal source rather than inward current.
Challenges inward current as sole CICR trigger; leaves open direct validation of sarcolemmal calcium sources.
We present information from the literature which is discordant with the idea that the trigger Ca2+ for Ca2(+)-induced Ca2+ release from the myocardial sarcoplasmic reticulum (SR) is carried by the inward current. In addition, evidence is emerging to show that recovery of contractility with increasing interval after an excitation-contraction-relaxation cycle (mechanical restitution) begins with repolarization of the sarcolemma, not mechanical relaxation (SR Ca2+ uptake). These two phenomena, if confirmed, would be compatible with a sarcolemmal source of trigger Ca2+.
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NOBLE et al. (1990) conducted a review in Myocardial cell calcium release. Mechanical restitution was evaluated. Evidence from the literature suggests that mechanical restitution begins with sarcolemma repolarization, compatible with a sarcolemmal source of trigger calcium in myocardial cells.
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