Lukyanetz E A
Bogomoletz Institute of Physiology, Bogomoletz Str. 4, Kiev-24, 01024, Ukraine.
Biochem Biophys Res Commun. 2001 Nov 9;288(4):844-8. doi: 10.1006/bbrc.2001.5844.
The relationship between Ca(2+) influx through voltage-activated Ca(2+) channels, resting intracellular Ca(2+) level (Ca(i)) and Ca(2+)-dependent exocytosis was studied in bovine adrenal chromaffin cells by using patch-clamp, capacitance, and fluorescent measurements. It was established that depolarization-induced exocytosis passed over two steps, both of which linearly depend on Ca(i). At Ca(i) lying below critical point (200-300 nM) the slope of the relationship was 4.43 and at Ca(i) exceeding the critical point the slope was equal to 31.63. The vesicular mechanism describing experimental two-step dependence of exocytosis on intracellular Ca(2+) (Ca(i)) is proposed. According to the model at Ca(i) below critical point only small-sized vesicles fuse with plasma membrane, whereas at higher Ca(i), larger vesicles started to fuse.
通过膜片钳、电容和荧光测量技术，研究了牛肾上腺嗜铬细胞中通过电压激活钙通道的钙离子内流、静息细胞内钙离子水平（Ca(i)）与钙离子依赖性胞吐作用之间的关系。研究发现，去极化诱导的胞吐作用分两个步骤进行，这两个步骤均与Ca(i)呈线性相关。当Ca(i)低于临界点（200 - 300 nM）时，这种关系的斜率为4.43，而当Ca(i)超过临界点时，斜率等于31.63。本文提出了一种囊泡机制，用于描述胞吐作用对细胞内钙离子（Ca(i)）的实验性两步依赖性。根据该模型，当Ca(i)低于临界点时，只有小尺寸囊泡与质膜融合，而当Ca(i)较高时，较大的囊泡开始融合。
