Regulatory mechonisms for pxocytosis

(1)浦肯野细胞gaba能突触后电流的增强。在培养的大鼠浦肯野细胞中记录自发性抑制性突触后电流（IPSCs）和诱发性IPSCs。在浦肯野细胞的膜去极化后，这些gaba能IPSCs的大小增加。这种增加是由于突触后膜中GABA反应的增加，而不是突触前GABA释放的增加，并且可能通过细胞内Ca浓度的增加和IP3诱导的Ca释放来激活PLC。(2)大鼠听觉传递核粘土型突触的发育。采用全细胞膜片记录技术对出生后4-13天（P4-P13）大鼠梯形体内侧核的突触传递进行了分析。在P4-P6动物中，诱发的EPSCs振幅波动较大，并以明显的非同行性发生，随后出现自发性EPSCs。随着动物的发育，诱发EPSCs的振幅增加，且上升时间变快。此外，突触传递成为锁相。EPSC振幅变异系数（CV）随发育而减小(P4-P5为0.32（]SY.+- - [)0.03， P9-P11为0.05(]SY.+- -[)0.01）。mepsc的振幅在出生后几天内没有变化（-30.2(]SY.+- [)0.3 pA，在-70 mV时）。CV依赖于细胞外Ca2+浓度（[Ca2+]o），并随着[Ca2+]o的增加而降低，随着发育，这种[Ca2+]o依赖性向较低的[Ca2+]o转移。突触前末端的直接贴片记录表明，在这些出生后的日子里，Ca2+电流增加。该突触的锁相高保真传输可能是通过增加Ca2+电流和突触前末端递质释放机制的Ca2+敏感性来实现的。

(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.