抄録
By finding a suggestive evidence that Ca2+ repletion in the junctional sarcoplasmic reticulum (JSR) occurs with a common JSR Ca2+ content versus time relationship after various degrees of JSR Ca2+ release, we have developed a method to estimate a time course of the JSR Ca2+ repletion after JSR Ca2+ release and JSR Ca2+ release/content relation by analyzing short-term mechanical restitution in cardiac muscle of murine hearts (Tameyasu, et al, Jpn J Physiol 2004). Though murine heart muscle is useful to study pathophysiology of heart failure because of development of model animals for heart disease, its SR handles Ca2+ in a different way from human cardiac muscle. In the present study, we applied our method to rabbit heart, the mechanical property of which resembles human heart, by measuring the left ventricular pressure. After the Ca2+ content of the SR in whole heart preparation isolated from rabbit was increased to a maximum level by 10 current pulses at 5 Hz at 37C in the presence of acetylcholine to suppress automaticity, double pulses with a various interval were applied externally to produce left ventricular systolic pressure of a desirable magnitude, which was followed by a test pulse to determine restitution of systolic pressure. Restitution of the left ventricular systolic pressure after systoles of various magnitudes was thus determined. The JSR Ca2+ release/content relation deduced from restitution of the left ventricular systolic pressure was somewhat different from that in rat cardiac muscle. [J Physiol Sci. 2008;58 Suppl:S177]
