Dynamics of vesicular tronsformation in maclear complex.

胰腺腺泡细胞的外核膜是粗糙的内质网（ER）膜。采用去核法收集核膜，采用标准膜片钳技术对这些制剂的外膜进行膜片钳处理。在单通道和全电流水平上，发现1)电压和Ca^<2+>激活的大k通道电流，2)一种向外的整流k通道电流，3)一种向内的整流cl通道电流。这些通道可能通过调节ip_3和/或环adp核糖依赖的Ca^<2+>-从内质网释放，促进细胞Ca^<2+>-信号转导。采用相敏电容测量方法，对膜电容变化的时间过程进行了监测。在局部斑块-膜水平上，这些变化是随机发生的，可以解释为可逆的囊泡形成（膜转化）。步骤的大小分布采用负指数曲线拟合，表明膜转化能量似乎只有一个能量峰。在全内质网水平上增加腔内Ca^<2+>-浓度，膜电容增加。这表明囊泡可逆地转化为帽状，囊泡内部与内质网腔之间有连接。结果提示内质网腔Ca^<2+>参与了囊泡运输。

The outer nuclear membrane of pancreatic acinar cells serves as a rough endoplasmic reticulum (ER) membrane. Collecting nuclear envelopes by enucleation, the standard patch-clamp techniques were applied to the outer membrane of these preparation. At the single channel and whole-current level, 1) voltage and Ca^<2+>-activated large K-channel current, 2) a type of outward-going rectifier K-channel current, 3) a type of inward-going rectifier Cl-channel current, were found. These channels may contribute to cellular Ca^<2+>-signaling through regulating IP_3-and/or cyclic ADP-ribose-dependent Ca^<2+>-release from the ER.Applying a phase-sensitive capacitance measurement to the ER preparation, the time course of the changes in membrane capacitance were monitored. At the local patch-membrane level, the changes occurred at random as discrete on-and off-steps, which can be interpreted as reversible vesicle formation (membrane transformation). The size distribution of the steps were fitted by a negative exponential curve, suggesting the membrane transformation energy seems to have a single energy peak. Increasing the lumenal Ca^<2+>-concentration at the whole-ER level, a rise in the membrane capacitance was found. This indicates that the vesicles are reversibly transformed to caps with a connection between the vesicle interior and the ER lumen. The result suggests the involvement of the ER lumenal Ca^<2+> in the vesicular transport.