Rouze N C, Schwartz E A
Department of Pharmacological and Physiological Sciences, The University of Chicago, Chicago, Illinois 60637, USA.
J Neurosci. 1998 Nov 1;18(21):8614-24. doi: 10.1523/JNEUROSCI.18-21-08614.1998.
Optical methods were used to study the Ca2+ dependence of vesicle cycling in bipolar cells isolated from goldfish retinas. Uniformly raising the Ca2+ concentration to between 0.8 and 20 microM produced a continuous vesicle cycle of balanced exocytosis and endocytosis with a maximum rate equivalent to the turnover of the entire surface membrane of a terminal every 2 min (or approximately 900 vesicles sec-1). Increasing the Ca2+ concentration above 20 microM inhibited continuous vesicle cycling. In contrast, influx of Ca2+ through voltage-gated channels produced a transient burst of exocytosis that increased the surface area of a terminal by a maximum of 12% (equivalent to the addition of 13,000 vesicles). Endocytosis was delayed until after Ca2+ influx stopped and the average Ca2+ concentration in the terminal declined. Hence, a single terminal has mechanisms for both continuous and transient vesicle cycling.
采用光学方法研究从金鱼视网膜分离出的双极细胞中囊泡循环对钙离子的依赖性。将钙离子浓度均匀提高到0.8至20微摩尔之间，会产生一个由平衡的胞吐作用和内吞作用组成的连续囊泡循环，最大速率相当于每2分钟使一个终末的整个表面膜更新一次（或约每秒900个囊泡）。将钙离子浓度提高到20微摩尔以上会抑制连续的囊泡循环。相反，通过电压门控通道流入的钙离子会产生一阵短暂的胞吐作用，使终末的表面积最大增加12%（相当于增加13,000个囊泡）。内吞作用会延迟到钙离子流入停止且终末内的平均钙离子浓度下降之后。因此，单个终末具有连续和短暂囊泡循环的机制。
