MINORITY PREDOCTORAL FELLOWSHIP PROGRAM

突触前钙离子浓度的突然增加， 动作电位的到达一直被假设，但从未被测量， 是突触传递中囊泡动员的关键要求。 我建议结合光学和电生理学 测量细胞内钙浓度快速变化的技术 由脊椎动物神经肌肉突触共同体中的动作电位引起， 培养物制备。 具体来说，我将使用共焦点检测 该方法提供了数十微秒的时间分辨率 和亚微米的空间分辨率来研究 突触前钙和钙激活钾电导 全细胞电压中细胞内钙瞬变的产生 突触前静脉曲张 此外， 笼状钙化合物DM-硝基酚将用于研究独立的 钙离子浓度变化在神经递质释放中的作用。 诱发性突触后电流和钙离子的同时测量 瞬态将提供定量数据，以测试电流模型 突触前钙浓度与神经递质的相关性 在神经肌肉接头处释放。 拟议中的实验将有助于 阐明突触前传导在活动区的机制， 当被动作电位打开时，可以在突触前产生梯度， 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.