Dynamics of vesicular tronsformation in maclear complex.

胰腺腺泡细胞外核膜为粗面内质网(ER)膜。通过去核收集核膜，将标准的膜片钳技术应用于这些制剂的外膜。在单通道和全电流水平，1)电压和钙激活的大K通道电流，2)一种外向整流K-通道电流，3)一种内向整流氯通道电流。这些通道可能通过调节内质网释放IP_3和/或循环ADP核糖依赖的Ca~(2+)而参与细胞内Ca~(2+)信号传导。在局部膜-膜水平上，这种变化是随机发生的，是离散的开和离步，可以解释为可逆的囊泡形成(膜转化)。阶跃的大小分布符合负指数曲线，表明膜的转变能似乎有一个单一的能量峰。在整个内质网水平上，随着胞膜Ca~(2+)浓度的增加，膜电容增大。这表明囊泡可逆地转化为帽，在囊泡内部和内质网管腔之间有连接。结果提示，内质网腔内钙离子参与囊泡转运。

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.