Menbrane phospholipase c activation and signal transduction in relation to change of receptor-linkage mechanism

膜磷脂酶 c 激活和信号转导与受体连接机制变化的关系

基本信息

批准号：
62480123
负责人：
KATO Ryuichi
金额：
$ 3.71万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

The mechanism of functional shift from muscarinic to nicotinic cholinergic receptors involved in cytosolic Ca^<++> mobilization and inositol triphosphate (IP_3) during the primary culture of adrenal chromaffin cells was studied. At 0.5 day in culture, muscarine, a specific agonist for muscarinic receptors, caused a greater effect on intracellular Ca^<2+> mobilization and the accumulation of Ins(1,3,4)P_3 than did the nicotinic-specific agonist nicotine. On the contrary, at 5 days, nicotine produced a greater effect on the accumulation of Ins(1,3,4)P_3 and intracellular calcium mobilization than did muscarine. Furthermore, at 0.5 day, the muscarinic antagonist atropine strongly inhibited the increase in InsP_3 accumulation that was induced by the nonspecific agonist carbachol, whereas at 5 days the inhibitory effect of atropine was greatly lowered. On the other hand, the nicotinic receptor antagonists hexamethonium and - tubocurarine showed a much higher inhibitory potency at 5 days compared with 0.5 day in culture. Binding experiments with a muscarinic ligand excluded the possibility that the reduction in muscarinic effects on InsP_3 and intracellular Ca^<2+> mobilization were due to disappearance of the muscarinic receptor itself. These data show that cholinergic receptors linked to the accumulation of InsP_3 and Ca^<2+> mobilization functionally shift from muscarinic to nicotinic during primary culture of adrenal chromaffin cells.

研究了肾上腺嗜铬细胞原代培养过程中涉及胞质Ca ++ 动员和肌醇三磷酸(IP_3)的从毒蕈碱受体到烟碱胆碱能受体的功能转变的机制。在培养0.5天时，毒蕈碱(毒蕈碱受体的特异性激动剂)对细胞内Ca 2+ 动员和Ins(1,3,4)P_3积累的影响比烟碱特异性激动剂尼古丁更大。相反，在第5天时，尼古丁对Ins(1,3,4)P_3的积累和细胞内钙动员的影响比毒蕈碱更大。此外，在0.5天时，毒蕈碱拮抗剂阿托品强烈抑制由非特异性激动剂卡巴胆碱诱导的InsP_3积累的增加，而在5天时阿托品的抑制作用大大降低。另一方面，烟碱受体拮抗剂六甲铵和筒箭毒碱在培养5天时显示出比培养0.5天时高得多的抑制效力。毒蕈碱配体的结合实验排除了对InsP_3和细胞内Ca 2+ 动员的毒蕈碱作用的降低是由于毒蕈碱受体本身消失的可能性。这些数据表明，在肾上腺嗜铬细胞的原代培养过程中，与InsP_3积累和Ca 2+ 动员相关的胆碱能受体在功能上从毒蕈碱转变为烟碱。