MINORITY PREDOCTORAL FELLOWSHIP PROGRAM

突触前钙浓度的突然升高是由 动作电位的到来一直被假设为，但从未测量到 是突触传递中囊泡动员的关键条件。 我建议实施光学和电生理的结合 快速测量细胞内钙离子浓度变化的技术 脊椎动物神经肌肉突触协同动作电位的诱发 培养准备。具体地说，我将使用共焦斑检测 方法，提供几十微秒的时间分辨率 以及亚微米的空间分辨率来研究 突触前钙和钙激活的钾电导 全细胞电压下细胞内钙瞬变的产生 夹闭性突触前静脉曲张。此外，闪光光解 笼状钙化合物DM-硝酚将用于研究独立的 钙浓度变化在神经递质释放中的作用。 诱发突触后电流和钙离子的同步测量 瞬变将提供量化数据来测试当前的模型 突触前钙浓度与神经递质的关系 在神经肌肉连接处释放。拟议中的实验将有所帮助 阐明活动区突触前电导的机制， 当被动作电位打开时，可能会在突触前产生梯度 最终调节神经递质释放的钙浓度。

A sudden increase in presynaptic calcium concentration triggered by the arrival of an action potential has been postulated, but never measured, to be the key requirement for vesicle mobilization in synaptic transmission. I propose to implement a combination of optical and electrophysiological techniques to measure fast intracellular calcium concentration changes elicited by action potentials in a vertebrate neuromuscular synaptic co- culture preparation. Specifically, I will use a confocal spot detection methodology, which provides a temporal resolution of tens of microseconds and a spatial resolution of sub microns to investigate the role of presynaptic calcium and calcium activated potassium conductances in the generation of intracellular calcium transients in whole cell voltage clamped presynaptic varicosities. In addition, flash photolysis of the caged calcium compound DM- nitrophen will be used to study the independent role of calcium concentration changes in releasing neurotransmitter. Simultaneous measurements of evoked postsynaptic currents and calcium transients will provide quantitative data to test current models correlating presynaptic calcium concentrations with neurotransmitter release at the neuromuscular junction. The proposed experiments will help elucidate the mechanisms by which presynaptic conductances at active zones, when opened by action potentials, may generate gradients in the presynaptic calcium concentration that ultimately modulate neurotransmitter release.