Do studies of mechanical restitution tell us anything about the mechanism of Ca2+ release in myocardial cells?
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+.
Academic Unit of Cardiovascular Medicine, Charing Cross and Westminster Medical School, London, UK.
M I
MI
Noble
A J
AJ
Drake-Holland
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006321:Heart / Q000502:physiology; D006801:Humans; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*
D002118:Calcium