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The physiological role and the control mechanism of Ca^<2+>-mobilization in stimulation-secretion coupling in parotid gland

Ca^2动员在腮腺刺激-分泌耦合中的生理作用及其控制机制

基本信息

批准号：
03670869
负责人：
TOJYO Yosuke
金额：
$ 1.28万
依托单位：
Higashi-Nippon-Gakuen University, School of Dentistry
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

Carbachol (CCh), a cholinergic agonist, increased both cytosolic free calcium concentration ([Ca^<2+>]_i) and amylase release in rat parotid acinar cells in a dose-dependent manner. Treatment of acinar cells with the intracellular Ca^<2+> antagonist TMB-8 or the intracellular Ca^<2+> chelator BAPTA strongly attenuated the increase in [Ca^<2+>]_i evoked by CCh, but did not significantly suppress amylase release. A combined addition of the Ca^<2+> ionophore ionomycin and the microsomal ATPase inhibitor thapsigargin to cell suspension caused a noticeable increase in [Ca^<2+>]_i, but the effect on amylase release was much smaller than that of CCh. When ATP was added to cell suspension, a rapid elevation of [Ca^<2+>]_i was observed. This [Ca^<2+>]_i response is unlikely to be mediated by PI breakdown, because ATP had little or no effect on IP_3 formation. Despite the marked increase in [Ca^<2+>]_i, amylase release was not induced by extracellular ATP. The protein kinase C activator PMA stimulated amylase release in quantities similar to those induced by CCh. Staurosporine, a protein kinase C inhibitor, similarly inhibited both the CCh-and TPA-induced amylase release. These results suggest that an increase in [Ca^<2+>]_i does not play an essential role in amylase release by muscarinic stimulation. The amylase release may be primarily mediated by activation of protein kinase c.On the other hand, treatment of cells with TMB-8 or BAPTA strongly suppressed the CCh-induced K^+ release. A combined addition of Iono and ThG caused a marked release of K^+, but PMA did not affect basal K^+ release or potentiate the CCh-induced K^+ release. These results indicate that the CCh-induced K^+ release is mediated by a rapid increase in [Ca^<2+>]_i but is not associated with activation of protein kinase C

卡巴胆碱(CCh)，一种胆碱能激动剂，以剂量依赖性方式增加大鼠腮腺腺泡细胞中的胞质游离钙浓度([Ca 2+ ]_i)和淀粉酶释放。用细胞内Ca 2+ 拮抗剂TMB-8或细胞内Ca 2+ 螯合剂BAPTA处理腺泡细胞强烈减弱CCh引起的[Ca 2+ ]_i的增加，但没有显着抑制淀粉酶释放。将Ca 2+ 离子载体离子霉素和微粒体ATP酶抑制剂毒胡萝卜素联合添加到细胞悬浮液中导致[Ca 2+ ]_i显着增加，但对淀粉酶释放的影响比CCh小得多。当将ATP添加到细胞悬浮液中时，观察到[Ca 2+ ]_i 快速升高。这种[Ca^<2+>]_i 反应不太可能由PI 分解介导，因为ATP 对IP_3 形成影响很小或没有影响。尽管[Ca^2+]_i显着增加，但淀粉酶释放不是由细胞外ATP诱导的。蛋白激酶 C 激活剂 PMA 刺激淀粉酶释放的量与 CCh 诱导的量相似。 Staurosporine 是一种蛋白激酶 C 抑制剂，同样可以抑制 CCh 和 TPA 诱导的淀粉酶释放。这些结果表明，[Ca 2+ ]_i 的增加在毒蕈碱刺激引起的淀粉酶释放中并不起重要作用。淀粉酶释放可能主要由蛋白激酶c 的激活介导。另一方面，用TMB-8 或BAPTA 处理细胞强烈抑制CCh 诱导的K^+ 释放。 Iono 和 ThG 的联合添加导致 K^+ 显着释放，但 PMA 不影响基础 K^+ 释放或增强 CCh 诱导的 K^+ 释放。这些结果表明，CCh 诱导的 K^+ 释放是由 [Ca^2+]_i 的快速增加介导的，但与蛋白激酶 C 的激活无关。