Calmodulin increases transmitter release by mobilizing quanta at the frog motor nerve terminal.
Calmodulin increases transmitter release by mobilizing quanta at the frog motor nerve terminal.
复制标题
钙调蛋白通过动员青蛙运动神经末梢的量子来增加递质的释放。
DOI：
10.1038/sj.bjp.0704923
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发表时间：
2002
影响因子：
7.3
通讯作者：
Dun,NaeJ
中科院分区：
文献类型：
--
作者：
Brailoiu,Eugen;Miyamoto,MichaelD;Dun,NaeJ
用脂质体将钙调素（CaM）和抗CaM单克隆抗体（antiCaM）直接导入蛙运动神经末梢，研究了CaM在递质释放中的作用。微型终板电位（MEPPs）记录在一个高K+的解决方案，和发射机释放的影响进行了监测，使用估计的量子释放参数m（释放的量子数），n（功能发射机释放网站的数量），p（平均释放概率），和变量p（空间方差p）。给药包封在脂质体（1000单位ml−1）中的CaM，而不是热灭活的CaM，会导致m增加（25%），这是由于n增加所致。MEPP振幅不被CaM改变。在脂质体（50 μl ml−1）中给予抗CaM（而不是热灭活的抗CaM）可使m逐渐降低（40%），这与n和p的降低有关。MEPP振幅在25 min滞后时间后降低（15%），表明量子释放和量子大小的降低之间存在时间上的分离。水浴应用膜渗透性CaM拮抗剂W7（28 μM）可使m逐渐降低（25%），这与n降低有关。W7也使MEPP振幅降低，使m降低。通过添加CaM，W7产生的MEPP尺寸和m的减少都被逆转。我们的研究结果表明，钙调素增加递质释放动员突触囊泡在青蛙运动神经末梢。
The role of calmodulin (CaM) in transmitter release was investigated using liposomes to deliver CaM and monoclonal antibodies against CaM (antiCaM) directly into the frog motor nerve terminal. Miniature endplate potentials (MEPPs) were recorded in a high K+ solution, and effects on transmitter release were monitored using estimates of the quantal release parameters m (number of quanta released), n (number of functional transmitter release sites), p (mean probability of release), and vars p (spatial variance in p). Administration of CaM, but not heat-inactivated CaM, encapsulated in liposomes (1000 units ml−1) produced an increase in m (25%) that was due to an increase in n. MEPP amplitude was not altered by CaM. Administration of antiCaM, but not heat-inactivated antiCaM, in liposomes (50 μl ml−1) produced a progressive decrease in m (40%) that was associated with decreases in n and p. MEPP amplitude was decreased (15%) after a 25 min lag time, suggesting a separation in time between the decreases in quantal release and quantal size. Bath application of the membrane-permeable CaM antagonist W7 (28 μM) produced a gradual decrease in m (25%) that was associated with a decrease in n. W7 also produced a decrease in MEPP amplitude that paralleled the decrease in m. The decreases in MEPP size and m produced by W7 were both reversed by addition of CaM. Our results suggest that CaM increases transmitter release by mobilizing synaptic vesicles at the frog motor nerve terminal.