CA++ CHANNELS AND STIMULUS SECRETION COUPLING

本研究的总体目标是首先了解 和嗜铬细胞钙通道的调节；第二，如何钙通道 和儿茶酚胺的分泌有关，并在不同的 嗜铬细胞。肾上腺髓质嗜铬细胞分泌 儿茶酚胺和几种神经肽激素对神经的反应 刺激。分泌是一个依赖于钙离子的过程，由 钙离子通过血浆电压门控性钙通道的内流 薄膜。因此，了解钙通道的特性是至关重要的 了解儿茶酚胺的分泌机制和调节。 我们发现牛嗜铬细胞含有三种不同类型的 钙通道，包括一类新的称为事实钙通道。这个 后者类似于在其他细胞中发现的“L型”钙通道，因为它们 具有27 ps的单通道电导，并且对 二氢吡啶类化合物。这些频道可以通过重复的方式招募 在生理范围内的去极化，通过去极化到非常 正电位或激活腺酰环化酶的神经递质 并通过PKA参与的机制升高细胞内cAMP。我们的工作 假设这些渠道可能是潜在的监管系统 在“不战即逃”的回答中。这些单元格还有另外两种类型 钙通道，两者都有14ps的电导。一种类型是 负责“非经典”的N型钙电流，而另一个 带有P型钙电流分量。我们建议：a)调查 在含有肾上腺素和去甲肾上腺素的体内存在这些通道 牛嗜铬细胞和猫嗜铬细胞；b)研究 不同化合物共存储和共释放对钙通道的调制 在胞吐过程中和c)研究分泌反应 三种细胞类型。特别是，我们将努力评估在多大程度上 每种钙通道都参与儿茶酚胺的分泌。比较 三种不同细胞类型的分泌数据可能不同 相同类型的钙通道的比率将使我们了解 这类通道在分泌调节中的作用。 通过同时研究钙电流(使用膜片钳 电生理学技术)和儿茶酚胺分泌(使用 电容测量)，我们希望揭示两者之间的关系 这两个关键参数。这些研究将扩大我们的理解 钙通道及其在儿茶酚胺分泌中的作用 突触神经递质释放的延长。

The overall goals of this research are to understand first, the function and regulation of chromaffin cell Ca channels and second, how Ca channels and catecholamine secretion are related and modulated in different chromaffin cells. The chromaffin cells of the adrenal medulla secrete catecholamines and several neuropeptide hormones in response to neural stimulation. Secretion is a Ca2+-dependent process that is triggered by the entry of Ca2+ through voltage-gated Ca channels in the plasma membrane. Thus, understanding the properties of Ca channels is essential to understanding the mechanism and regulation of catecholamine secretion. We have found that bovine chromaffin cells contain three distinct types of Ca channel, including a novel class known as faciliation Ca channels. The latter resemble "L-type" Ca channels found in other cells, in that they have a single channel conductance of 27 pS and are sensitive to dihydropyridines. These channels can be recruited by repetitive depolarizations in the physiological range, by depolarization to very positive potentials or by neurotransmitters that activate adenylyl cyclase and elevate intracellular cAMP by a mechanism involving PKA. Our working hypothesis is that these channels may be the underlying regulatory system in the "fight or flight" response. These cells also have two other types of Ca channels, both of which have a 14 pS conductance. One type is responsible for the "non classical" N-type Ca current, while the other carries a P-type Ca current component. We propose to: a) investigate the presence of these channels in epinephrine - and norepinephrine-containing bovine chromaffin cells as well as the feline chromaffin cells; b) study Ca channel modulation by different compounds co-stored and co-released during the exocytotic process and c) study the secretory response in the three cell types. In particular, we will try to evaluate to what extent each type of Ca channel participates in catecholamine secretion. Comparing secretion data from three different cell types with possibly different ratios of the same types of Ca channels will allow us to understand the role of such channels in the regulation of secretion. By simultaneously studying Ca currents (using patch-clamp electrophysiology techniques) and catecholamine secretion (using capacitance measurements), we hope to uncover the relationship between these two critical parameters. These studies will expand our understanding of Ca channels in general and their role in catecholamine secretion and by extension in synaptic neurotransmitter release.