Nerve activity but not intracellular calcium determines the time course of endocytosis at the frog neuromuscular junction

被引:144
作者
Wu, LG [1 ]
Betz, WJ [1 ]
机构
[1] UNIV COLORADO,SCH MED,DEPT PHYSIOL,DENVER,CO 80262
关键词
D O I
10.1016/S0896-6273(00)80208-1
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
We used FM1-43 imaging and intracellular recordings of synaptic potentials to measure the time course of endocytosis in frog motor nerve terminals following tetanic nerve stimulation, and we used fura-2 imaging of intraterminal Ca2+ concentration to compare endocytic rate and [Ca2+](i). Following a 30 Hz tetanus, endocytosis declined exponentially with a time constant that depended on the duration of stimulation. The level of [Ca2+](i) rose from a resting value of about 100 nM to more than 500 nM during 30 Hz stimulation, and rapidly declined to 200-250 nM after stimulation. [Ca2+](i) returned to resting level with a time course that, like endocytosis, depended on the duration of tetanic stimulation. However, the rate of [Ca2+](i) recovery was much slower than the rate of endocytosis, leading to the conclusion that endocytic rate is not determined solely by the instantaneous level of [Ca2+](i).
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页码:769 / 779
页数:11
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