RECEPTOR-MEDIATED CALCIUM ENTRY IN ACINAR CELLS

受体介导的腺泡细胞钙内流 钙(Ca~(2+))是连接细胞刺激的最终信使 腺泡细胞的分泌物。细胞刺激导致 细胞内钙离子浓度([Ca~(2+)]i) 通过可溶性第二信使的作用在细胞内储存。这 释放会导致细胞内钙存储的耗尽。受体- 介导的钙内流(RMCE)是一个受体激活的过程 不依赖于膜电位来调节钙离子的进入。RCME是 在激动剂刺激分泌细胞后观察到的，这是必要的 “补充”钙储存，恢复细胞反应能力。一份 已被证明在分泌细胞中的RMCE依赖于 细胞内钙库的“空”，这里将被称为 耗竭-激活的钙离子进入。这个项目的长期目标是 描述耗竭激活的钙离子内流的机制和 负责其功能的细胞内信使或机制 监管。关于耗竭激活钙的机制的详细说明 进入，或其监管，仍然未知。候选人的初选 实验表明：a)耗竭激活的钙离子进入 用膜片钳技术测量钙离子耗竭的腺泡细胞 Fura-2荧光，b)硝普钠，提高细胞内周期 喹苷-3，5-一磷酸，可促进钙内流。具体的 研究的目的是：a)界定对消耗的管制-- 通过确定环核苷酸或其他物质如何激活钙内流 信使起到调节钙离子进入的作用，b)决定是否 耗竭激活的钙离子进入由第二个信使操作 钙离子通道或其他机制，如离子交换器；这些 实验将使用两种膜片钳记录Fura-2荧光 测量。这些方法的适用性和可行性已经得到了验证。 在初步研究中得到了证实。这些初步研究提供了 有证据表明，拟议的实验将产生有用的结果。 GRANT-R01NS23077 癫痫是一种主要的中枢神经系统衰弱疾病。 它的特点是大脑的异常电活动。这 疾病影响着数百万人的生活。尽管癫痫可以是 在许多情况下接受药物治疗，有相当数量的患者 对药物治疗很难对付。这项研究计划的目的是 确定人类癫痫的细胞机制，以帮助 在开发更好的癫痫障碍治疗方法方面。蜂窝手机 癫痫发作活动的机制将通过研究 发生在颞叶齿状回的电活动 癫痫患者。齿状回在脑海马齿状回中占有重要地位。 对海马区电活动的控制，海马区是脑电活动的重要部位 癫痫发作开始。海马齿状回神经元的电活动 将在颞叶癫痫患者的脑片中检查脑回 病人。兴奋性突触和抑制性突触的相对影响 和固有膜特性对神经细胞超兴奋性的影响 将检查齿状回。关于纵向梯度的假设 在齿状回的过度兴奋性(癫痫敏感性)中 通过在沿线的几个地点进行生理记录进行测试 齿状回。对这些生理观察的解释 将由组织学评估(突触重组和 细胞丢失)来自相同区域的组织。建议的结果 实验将提供非常需要的关于 癫痫障碍的生理基础。

Receptor Mediated Calcium Entry in Acinar Cells Calcium (Ca2+) is the final messenger coupling cellular stimulation to secretion in acinar cells. Cellular stimulation causes a rise in intracellular Ca2+ concentration ([Ca2+]i) when Ca2+ is released from intracellular stores via the action of soluble second messengers. This release results in the depletion of intracellular Ca2+ stores. Receptor- mediated calcium entry (RMCE) is a process whereby receptor activation mediates calcium entry independently of membrane potential. RCME is observed after agonist stimulation in secretory cells, and is necessary to "refill" calcium stores and to restore cellular responsiveness. A portion of RMCE in secretory cells has been shown to be dependent on the "emptiness" of intracellular calcium stores and will be refereed to here as depletion-activated calcium entry. The long-range goal of this project is to describe the mechanism of depletion-activated calcium entry and the intracellular messengers or mechanisms that are responsible for its regulation. Details about the mechanism of depletion-activated calcium entry, or its regulation, remain unknown. The candidate's preliminary experiments have shown that: a) Depletion-activated calcium entry can be measured in Ca2+ depleted acinar cells using the patch-clamp technique and FURA-2 fluorescence, b) nitroprusside, which raises intracellular cyclic quanosine-3,5-monophosphate, can potentiate calcium entry. The specific aims of the research are: a) to define the regulation of depletion- activated calcium entry by determining how cyclic nucleotides or other messengers act to modulate calcium entry, and b) to determine whether depletion-activated calcium entry is carried by a second messenger-operated Ca2+ channel or by another mechanism such as an ion exchanger; these experiments will use both patch-clamp recording a FURA-2 fluorescence measurements. The suitability and feasibility of the methods have been demonstrated in the preliminary studies. These preliminary studies provide evidence that the proposed experiments will yield useful results. GRANT-R01NS23077 Epilepsy is a major debilitating disorder of the central nervous system which is characterized by abnormal electrical activity of the brain. This disease affects the lives of millions of people. Although epilepsy can be treated in many cases with drug therapy, a significant number of patients are intractable to drug treatment. The aim of this research plan is to determine the cellular mechanisms of epilepsy in humans, in order to assist in developing improved treatments for seizure-disorders. The cellular mechanisms of seizure activity will be investigated by studying the electrical activity which occurs in the dentate gyrus of temporal lobe epileptic patients. The dentate gyrus holds a crucial position in the control of electrical events in the hippocampus, an important site of seizure initiation. The electrical activity of neurons in the dentate gyrus will be examined in brain slices from temporal lobe epileptic patients. The relative influences of excitatory and inhibitory synaptic input, and intrinsic membrane properties on hyperexcitability of the dentate gyrus will be examined. The hypothesis of a longitudinal gradient in hyperexcitability (seizure susceptibility) of the dentate gyrus will be tested by performing physiological recordings at several locations along the dentate gyrus. The interpretation of these physiological observations will be assisted by histological assessment (synaptic reorganization and cell loss) of tissue from the same regions. The results from the proposed experiments will provide greatly needed information concerning the physiological basis of seizure disorders.