Pan C Y, Kao L S
Institute of Biomedical Sciences, Academia Sinica, and Department of Biochemistry, National Yang-Ming University, Taipei, Taiwan, Republic of China.
J Neurochem. 1997 Sep;69(3):1085-92. doi: 10.1046/j.1471-4159.1997.69031085.x.
The role of the Na+/Ca2+ exchanger and intracellular nonmitochondrial Ca2+ pool in the regulation of cytosolic free calcium concentration ([Ca2+]i) during catecholamine secretion was investigated. Catecholamine secretion and [Ca2+]i were simultaneously monitored in a single chromaffin cell. After high-K+ stimulation, control cells and cells in which the Na+/Ca2+ exchange activity was inhibited showed similar rates of [Ca2+]i elevation. However, the recovery of [Ca2+]i to resting levels was slower in the inhibited cells. Inhibition of the exchanger increased the total catecholamine secretion by prolonging the secretion. Inhibition of the Ca2+ pump of the intracellular Ca2+ pool with thapsigargin caused a significant delay in the recovery of [Ca2+]i and greatly enhanced the secretory events. These data suggest that both the Na+/Ca2+ exchanger and the thapsigargin-sensitive Ca2+ pool are important in the regulation of [Ca2+]i and, by modulating the time course of secretion, are important in determining the extent of secretion.
研究了钠钙交换体和细胞内非线粒体钙库在儿茶酚胺分泌过程中对胞质游离钙浓度（[Ca2+]i）调节的作用。在单个嗜铬细胞中同时监测儿茶酚胺分泌和[Ca2+]i。高钾刺激后，对照细胞和钠钙交换活性受抑制的细胞显示出相似的[Ca2+]i升高速率。然而，受抑制细胞中[Ca2+]i恢复到静息水平的速度较慢。交换体的抑制通过延长分泌时间增加了儿茶酚胺的总分泌量。用毒胡萝卜素抑制细胞内钙库的钙泵导致[Ca2+]i恢复显著延迟，并极大地增强了分泌事件。这些数据表明，钠钙交换体和对毒胡萝卜素敏感的钙库在调节[Ca2+]i方面都很重要，并且通过调节分泌的时间进程，在决定分泌程度方面也很重要。
