Ca2+- and GTP-dependent exocytosis in mouse pancreatic beta-cells involves both common and distinct steps
Ca2+- and GTP-dependent exocytosis in mouse pancreatic beta-cells involves both common and distinct steps
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小鼠胰腺β细胞的 Ca2+- 和 GTP 依赖性外泌涉及共同和不同的步骤
DOI：
10.1113/jphysiol.1996.sp021682
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发表时间：
1996-10-01
影响因子：
5.5
通讯作者：
Ashcroft, FM
中科院分区：
文献类型：
--
作者：
Proks, P;Eliasson, L;Ashcroft, FM
1.对单个胰腺β细胞GTP和Ca2+分泌的影响。GTP或GTP γ S在细胞内钙缺乏的情况下产生细胞电容的浓度依赖性增加。cAMP和BAPTA对GTP诱导的分泌无影响.在GTP的情况下，细胞内钙浓度和分泌的最大速率之间的关系拟合的希尔方程的斜率因子为2.5和半最大激活在1.6 μ M的细胞内Ca2+。在GTP γ S存在下获得类似的值，表明GTP不改变分泌机制对Ca 2+的敏感性。单独的GDP β S对细胞电容没有影响，但是引起了由输注GTP γ S或Ca2+诱导的胞吐的剂量依赖性抑制，这表明两种刺激都涉及G蛋白活化。GDP β S对去极化介导的Ca2+内流诱发的胞吐作用没有影响.胞吐作用的时间过程后快速升高GTP γ S的笼前体的光解依赖于细胞内Ca 2+和环AMP浓度。6.我们的研究结果被解释在一个模型中，由Ca2+和GTP刺激的分泌途径包含共同的和单独的部分。
1. The effects of GTP and Ca2+ secretion from single pancreatic beta-cells wer2. GTP or GTP gamma S produced a concentration-dependent increase in cell capacitance in the absence of intracellular calcium. There was no effect of cyclic AMP or BAPTA on GTP-induced secretion.3. In the absence of GTP, the relationship between intracellular calcium concentration and the maximum rate of secretion was fitted by the Hill equation with a slope factor of 2.5 and half-maximal activation at 1.6 mu M intracellular Ca2+. Similar values n ere obtained in the presence of GTP gamma S, suggesting GTP does not alter the sensitivity of the secretory machinery to Ca2+.4. GDP beta S alone had no effect on cell capacitance but caused a dose-dependent inhibition of exocytosis induced by infusion of either GTP gamma S or Ca2+, suggesting both stimuli involve G-protein activation. GDP beta S was without effect on exocytosis evoked by depolarization-mediated Ca2+ entry.5. The time course of exocytosis following rapid elevation of GTP gamma S by photolysis of a caged precursor was dependent on the intracellular Ca2+ and cyclic AMP concentrations. 6. Our results are interpreted in terms of a model in which the secretory pathways stimulated by Ca2+ and GTP contain both common and separate parts.