Intragranular pH rapidly modulates exocytosis in adrenal chromaffin cells
Intragranular pH rapidly modulates exocytosis in adrenal chromaffin cells
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DOI：
10.1111/j.1471-4159.2005.03526.x
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发表时间：
2006-01-01
影响因子：
4.7
通讯作者：
Borges, R
中科院分区：
文献类型：
--
作者：
Camacho, M;Machado, JD;Borges, R
几种药物使儿茶酚胺的胞吐动力学发生快速变化，这是用安培法在单粒子水平上测量的。这项研究旨在揭示这些效应的机制(S)是否涉及囊泡内pH的变化。细胞与囊泡质子泵阻断剂巴菲霉素A1孵育后，胞吐动力学减慢，囊泡儿茶酚胺含量减少。在用黑素或NH4Cl降低质子梯度时，也观察到了这些效应。用荧光探针(吖啶橙、喹啉或增强型绿色荧光蛋白突触素)测量的pH表明，囊泡的pH与胞吐动力学之间有很强的相关性。因此，所有的动作都测试了减速的胞吐作用也会使分泌囊泡碱化，反之亦然。另一方面，钙内流导致颗粒的一过性酸化。因此，我们认为，囊泡pH的调节至少部分是某些细胞信号调控胞吐作用和量子大小的动力学过程中的必要步骤。
Several drugs produce rapid changes in the kinetics of exocytosis of catecholamines, as measured at the single event level with amperometry. This study is intended to unveil whether the mechanism(s) responsible for these effects involve changes in the intravesicular pH. Cell incubation with bafilomycin A1, a blocker of the vesicular proton pump, caused both a deceleration in the kinetics of exocytosis and a reduction in the catecholamine content of vesicle. These effects were also observed upon reduction of proton gradient by nigericin or NH4Cl. pH measurements using fluorescent probes (acridine orange, quinacrine or enhanced green fluorescent protein-synaptobrevin) showed a strong correlation between vesicular pH and the kinetics of exocytosis. Hence, all maneuvers tested that decelerated exocytosis also alkalinized secretory vesicles and vice versa. On the other hand, calcium entry caused a transient acidification of granules. We therefore propose that the regulation of vesicular pH is, at least partially, a necessary step in the modulation of the kinetics of exocytosis and quantal size operated by some cell signals.