Post J A, Kuwata J H, Langer G A
Institute of Biomembranes, State University of Utrecht, The Netherlands.
Cell Calcium. 1993 Jan;14(1):61-71. doi: 10.1016/0143-4160(93)90019-3.
A pool of calcium has been identified in cultured neonatal rat heart cells whose exchange is dependent on extracellular sodium and calcium. In the absence of extracellular sodium and calcium this pool retains at least 760 mumol calcium/kg dry weight, which is released upon the introduction of sodium and calcium, with a t1/2 of 4.4 s. Video microscopy experiments of non-stimulated cells showed that the cells, despite the retention of 760 mumoles calcium/kg dry weight, do not develop contracture, indicating that the majority of the pool is not retained in the general cytoplasm. Neither is the pool displaced by lanthanum. Several probes for the sarcoplasmic reticulum were used. Ryanodine (1 microM) had no significant effect on the size of the pool. Caffeine reduced the size of the pool by 60% and thapsigargin, an inhibitor of the sarcoplasmic reticulum Ca-ATPase reduced the content of the pool by 70%. High concentrations of ryanodine (1 mM) reduced the pool even further. The experimental data, in association with recently developed concepts of the diadic region [1], indicate that the pool may reside in the sub-sarcolemmal space between the sarcoplasmic reticulum and the sub-sarcolemma. The physiological significance of this pool is discussed.
在培养的新生大鼠心脏细胞中已鉴定出一个钙池，其钙交换依赖于细胞外钠和钙。在没有细胞外钠和钙的情况下，这个钙池至少保留760微摩尔钙/千克干重，在引入钠和钙后会释放，半衰期为4.4秒。对未刺激细胞的视频显微镜实验表明，尽管细胞保留了760微摩尔钙/千克干重，但并未发生挛缩，这表明该钙池的大部分并未保留在普通细胞质中。该钙池也不会被镧取代。使用了几种针对肌浆网的探针。ryanodine（1微摩尔）对钙池大小没有显著影响。咖啡因使钙池大小减少了60%，而肌浆网Ca-ATP酶抑制剂毒胡萝卜素使钙池含量减少了70%。高浓度的ryanodine（1毫摩尔）进一步减少了钙池。实验数据与最近发展的二联体区域概念[1]相结合，表明该钙池可能存在于肌浆网和肌膜下之间的肌膜下空间。讨论了这个钙池的生理意义。
