Fabiato A
Fed Proc. 1982 May;41(7):2238-44.
The Ca2+-induced release of Ca2+ from he sarcoplasmic reticulum (SR) is not an all-or-none process but is graded with 1) the level of preload of the SR with Ca2+, 2) the rate of change of [free CA2+], and 3) the level of [free CA2+] used as a trigger. Among adult ventricular cardiac tissues the Ca2+-induced release of Ca2+ is absent in the frog ventricle, but present in avian and all mammalian ventricular tissues studied with large variations among species and maximum prominence in the rat ventricle. During the development of the rat ventricular cell there is a progressive maturation of the Ca2+-induced release of Ca2+, which is absent before birth. In the same animal species the Ca2+-induced release of Ca2+ is more developed in the atrium than in the ventricle. In the dog cardiac Purkinje tissue a higher [free Ca2+] preload and a higher [free Ca2+] trigger are required than for the dog ventricle. A working hypothesis is suggested according to which the mechanism of excitation-contraction coupling increases in complexity as the diameter of the cell increases, with maximum complexity presented by the fast skeletal muscle cell.
钙离子诱导的肌浆网（SR）中钙离子释放并非全或无的过程，而是呈分级变化，其与以下因素有关：1）肌浆网中钙离子的预负荷水平；2）[游离钙离子]的变化速率；3）用作触发因素的[游离钙离子]水平。在成年心室心肌组织中，蛙心室不存在钙离子诱导的钙离子释放，但在已研究的鸟类和所有哺乳动物心室组织中存在，不同物种间差异很大，在大鼠心室中最为显著。在大鼠心室细胞发育过程中，钙离子诱导的钙离子释放逐渐成熟，出生前不存在。在同一动物物种中，心房中钙离子诱导的钙离子释放比心室中更发达。在犬心脏浦肯野组织中，与犬心室相比，需要更高的[游离钙离子]预负荷和更高的[游离钙离子]触发水平。提出了一个可行的假说，即随着细胞直径增加，兴奋 - 收缩偶联机制的复杂性增加，快速骨骼肌细胞表现出最大的复杂性。
