SIMULTANEOUS ELECTRICAL AND OPTICAL MEASUREMENTS SHOW THAT MEMBRANE-FUSION PRECEDES SECRETORY GRANULE SWELLING DURING EXOCYTOSIS OF BEIGE MOUSE MAST-CELLS
SIMULTANEOUS ELECTRICAL AND OPTICAL MEASUREMENTS SHOW THAT MEMBRANE-FUSION PRECEDES SECRETORY GRANULE SWELLING DURING EXOCYTOSIS OF BEIGE MOUSE MAST-CELLS
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DOI：
10.1073/pnas.84.6.1585
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发表时间：
1987-03-01
影响因子：
11.1
通讯作者：
BRODWICK, M
中科院分区：
文献类型：
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作者：
ZIMMERBERG, J;CURRAN, M;BRODWICK, M
肥大细胞在进行胞吐作用时表现出显着的形态变化。我们已经研究了这些形态变化中的第一个，即分泌颗粒的肿胀，是否先于sbd并因此可能启动sbd分泌，或者它是否发生在颗粒和质膜融合之后。我们使用细胞膜电容来检测颗粒和质膜变得连续的时刻。我们测量到电容大幅增加，通常先出现电容瞬变。电容增加的上升时间在 2-59 毫秒处为最大一半。在进行这些测量时，我们用高分辨率视频显微镜观察了细胞。电容增加总是先于导致胞吐作用的颗粒膨胀。为了排除由拉紧颗粒的内部压力产生的机械应力诱导融合的可能性，我们使用用高渗溶液收缩囊泡的细胞进行了对照实验。对于这些松弛的颗粒，电容的上升总是先于颗粒的膨胀。我们得出的结论是，膨胀不能成为该系统中膜融合的驱动力。
Mast cells show dramatic morphological changes when undergoing exocytosis. We have investigated whether the first of those morphological changes, swelling of the secretory granule, precedes.sbd.and therefore possibly initiates.sbd.secretion or whether it occurs after fusion of the granule and plasma membranes. We used cell membrane capacitance to detect the moment when granule and plasma membrane become continuous. We measured large capacitance increases, often preceded by transients in capacitance. The rise-times of the capacitance increases were half-maximal at 2-59 msec. We observed cells with high-resolutoin video microscopy while these measurements were done. The capacitance increase always preceded the granular swelling that leads to exocytosis. To rule out the possibility that fusion was induced by a mechanical stress imparted by the internal pressure of a taut granule, we performed control experiments using cells in which vesicles were shrunken with hyperosmotic solutions. With these flaccid granules, again, the capacitance rise always preceded the swelling of the granules. We conclude that swelling cannot be the driving force for membrane fusion in this system.