Chowdhury H H, Popoff M R, Zorec R
Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Medical School, Ljubljana, Slovenia.
Pflugers Arch. 2000;439(3 Suppl):R148-9.
We monitored secretory activity of single rat melanotrophs by the patch-clamp membrane capacitance measurements (Cm). Secretory activity was stimulated by cytosol dialysis with a patch-pipette solution containing 1 microM [Ca2+]i. Actin cytoskeleton was disaggregated by pretreating cells with Clostridium spiroforme toxin, which specifically ADP-ribosylates cellular actin. The extent of cytoskeleton disaggregation was monitored by phalloidin immunostaining. The maximal rate of secretion increases two folds in toxin-treated cells in comparison to controls, whereas the extent of calcium-induced secretory response was similar to that obtained in the non-treated cells. The results show that the subcortical actin network attenuates the rate of secretory activity, which we interpret to reflect a barrier function of cytoskeleton for exocytosis.
我们通过膜片钳膜电容测量（Cm）监测单个大鼠促黑素细胞的分泌活性。用含有1微摩尔[Ca2+]i的膜片吸管溶液进行胞质透析来刺激分泌活性。用螺旋体梭菌毒素预处理细胞使肌动蛋白细胞骨架解聚，该毒素特异性地对细胞肌动蛋白进行ADP核糖基化。通过鬼笔环肽免疫染色监测细胞骨架解聚的程度。与对照组相比，毒素处理细胞的最大分泌速率增加了两倍，而钙诱导的分泌反应程度与未处理细胞相似。结果表明，皮层下肌动蛋白网络会减弱分泌活性的速率，我们认为这反映了细胞骨架对外吐作用的屏障功能。
