Kasai M, Miyamoto H
J Biochem. 1976 May;79(5):1053-66. doi: 10.1093/oxfordjournals.jbchem.a131147.
Ca2& taken up by sarcoplasmic reticulum membrane fragments (SRF) upon using ATP could be released rapidly by changing the anion outside the vesicles from methanesulfonate to chloride. It is considered that this anion exchange caused depolarization of the sarcoplasmic reticulum membrane. Similar rapid release of Ca2& taken up by SRF was also caused by a change from high to low osmotic pressure, probably due to bursting of the membrane. On the basis of experiments in which these two types of Ca2& release were discriminated, it was concluded that Ca2& bound inside the membrane was released directly by anion exchange (depolarization). However, Ca2& release was not caused by cation exchange. Sucrose inhibited these two types of Ca2& release. Cia2& taken up in the presence of oxalate could not be released by any treatment used. Liver microsome fraction also has Ca2& uptake activity. However, Ca2& was not released upon anion exchange, but was released upon oxmotic change. These results show that Ca2& release from SRF upon anion exchange is specific to the sarcoplasmic reticulum membrane. In conclusion, SRF membrane retains the ability to respond to the depolarization caused by ion exchange and can release the accumulated Ca2&.
当使用ATP时，被肌浆网碎片（SRF）摄取的Ca2+可通过将囊泡外部的阴离子从甲磺酸盐变为氯化物而迅速释放。据认为，这种阴离子交换导致了肌浆网膜的去极化。从高渗透压变为低渗透压也会导致SRF摄取的Ca2+类似的快速释放，这可能是由于膜破裂所致。基于区分这两种类型Ca2+释放的实验，得出结论：膜内结合的Ca2+通过阴离子交换（去极化）直接释放。然而，阳离子交换不会引起Ca2+释放。蔗糖抑制这两种类型的Ca2+释放。在草酸盐存在下摄取的Ca2+不能通过任何所用处理释放。肝微粒体部分也具有Ca2+摄取活性。然而，阴离子交换时Ca2+不会释放，但渗透压改变时会释放。这些释放。这些结果表明，阴离子交换时SRF释放Ca2+是肌浆网膜特有的。总之，SRF膜保留了对离子交换引起的去极化作出反应并释放积累的Ca2+的能力。
