Regulatory mechonisms for pxocytosis

(1)浦肯野细胞GABA能突触后电流的增强。从培养的大鼠浦肯野细胞中记录了自发抑制性突触后电流（IPSC）和诱发的IPSC。浦肯野细胞膜去极化后，这些GABA能IPSC的大小增加。这种增加是由于突触后膜GABA反应的增加而不是突触前GABA释放的增加，并且可能与通过增加细胞内Ca浓度和IP 3诱导的Ca释放激活PLC相耦合。(2)大鼠听觉中继核团粘土型突触相位传递的生后发育。应用脑片全细胞膜片钳记录技术，对出生后4-13天（P4-P13）大鼠斜方体内侧核（MNTB）内的突触传递进行了研究。在P4-P6动物中，诱发性EPSC的振幅波动较大，出现明显的节律性，随后出现自发性EPSC。随着动物的发育，诱发的EPSC的振幅增加，上升时间变快。此外，突触传递变得锁相。EPSC波幅的变异系数（CV）随年龄增长而降低（0.32 ± 0.05）。P4-P5为0.03，P4-P5为0.05，P4-P5为0.05。[）P9-P11为0.01）。mEPSC的振幅在整个研究的出生后天数中没有变化（-30.2（± SD）。[)0.3 pA，-70 mV）。CV依赖于细胞外Ca ~（2+）浓度（[Ca ~（2+）]o），随[Ca ~（2+）]o的增加而降低，并随发育向低[Ca ~（2+）]o方向转移。突触前末梢的直接贴片记录表明，在这些出生后的日子里，Ca 2+电流增加。这种突触的锁相高保真传递可能是通过突触前末梢的Ca ~（2+）电流和递质释放机制的Ca ~（2+）敏感性的增加而实现的。

(1) Potentiation of GABAergic postsynaptic currents in the Purkinje cells. Spontaneous inhibitory postsynaptic currents (IPSCs) and evoked IPSCs were recorded from cultured Purkinje cells of the rat. Size of these GABAergic IPSCs were increased after membrane depolarization of Purkinje cells. The increase was due to the increased GABA response in the postsynaptic membrane rather than the increased release of GABA presynapitcally, and was likely coupled with the activation of PLC through the increased intracellular Ca concentration and the IP3 induced Ca release.(2) Postnatal development of phasic transmission in the clayx type synapse in the auditory relay nucleus of rat. Synaptic transmission in the medial nucleus of the trapezoid body (MNTB) of rats was analyzed in postnatal days of 4-13 (P4-P13) by applying the whole cell patch recording technique to brain slices. In P4-P6 animals, evoked EPSCs fluctuated extensively in amplitude and occurred in marked asynchrony, follwed by spontaneous EPSCs. With development of animals, the evoked EPSCs increased in amplitude, and the rise time became faster. In addition the synaptic transmission became phase-locked. The coefficient of variation (CV) of EPSC amplitude decreased with development (0.32(]SY.+-。[)0.03 for P4-P5 and 0.05(]SY.+-。[)0.01 for P9-P11). The amplitude of mEPSCs did not change throughout the postnatal days investigated (-30.2(]SY.+-。[)0.3 pA,at -70 mV). The CV was dependent on extracellular Ca2+ concentration ([Ca2+]o) and was reduced with the increase of [Ca2+]o, and this [Ca2+]o dependence was shifted towards lower [Ca2+]o with development. Direct patch recording of the presynaptic terminals demonstrated an increase in Ca2+ currents during these postnatal days. The phase-locked high-fidelity transmission in this synapse is achieved with development likely through the increase of Ca2+ currents and Ca2+ sensitivity of transmitter release mechanisms in the presynaptic terminal.