咖啡因对大鼠肾上腺嗜铬细胞钙信号调节作用

在单个大鼠肾上腺嗜铬细胞上，采用钙显微荧光测量方法，测量了咖啡因对胞内游离钙浓度的影响．实验结果表明，在２Ｃａ２＋外液中，咖啡因（１ｍｍｏｌ／Ｌ，１０ｍｍｏｌ／Ｌ，４０ｍｍｏｌ／Ｌ）对细胞的自发振荡表现出明显的抑制作用；对不表现自发振荡的细胞，咖啡因能引起钙浓度的升高或钙振荡．在无外钙条件下研究连续咖啡因刺激引起的钙浓度变化，发现胞内钙库易排空，但随后的含钙咖啡因刺激仍可引起钙升高．同时，在无外钙条件下施加咖啡因可检测到激素的分泌，表明由咖啡因导致的钙库释放可以独立地触发分泌

On Caffeine Controlling over the Calcium Signal in Single Rat Adrenal Chromaffin Cells

Using microflurescent calcium measurement techniques,the effects of caffeine on the Ca 2+ ] i of single rat chromaffin cells are studied. In 2Ca 2+ containing extracellular solution, the applications of caffeine (1mmol/L, 10mmol/L, or 40mmol/L) always block their spontaneous oscillation. To silent cells,caffeine often leads to calcium transients or calcium oscillation. When the cells stimulated by caffeine successively in Ca 2+ free conditions, the calcium stores were emptied easily, but the subsequent application of caffeine containing Ca 2+ still can elevate Ca 2+ ] i. Under Ca 2+ free conditions, the applications of caffeine also can result in the secretion of hormones. It is verified that the release of calcium stores induced by caffeine can lead to secretion independently of extracellular calcium.