CONTROL OF CELL CALCIUM IN PANCREATIC ACINAR CELLS

胰腺腺泡细胞中细胞钙的控制

• 批准号: 3447366
• 负责人: DUANE L OCHS
• 金额: $ 5.09万
• 依托单位: VIRGINIA POLYTECHNIC INST AND ST UNIV
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-12-01 至 1987-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3447366
• 关键词: adenosinetriphosphatase; amylases; calcium metabolism; carbachol; cell membrane; cholecystokinin; endoplasmic reticulum; exocytosis; fluorescent dye /probe; inositol phosphates; ion transport; membrane potentials; pancreas enzyme; pancreatic islets

For over twenty years it has been proposed that calcium acts as a secondary messenger during stimulus-secretion coupling. Only recently, however, has it been shown that the concentration of free cytosolic calcium ([Ca2+]i) of pancreatic acinar cells increases following stimulation by secretagogues. Using the calcium-selective fluorescent indicator quin-2, the PI has demonstrated that a rapid, five-fold enhancement of [Ca2+]i occurs in acinar cells following stimulation by either the hormone cholecystokinin or carbachol, an analog of the neurotransmitter acetylcholine. One goal of this proposal is to characterize the properties of this transient rise in [Ca2+]i and to investigate its role in enzyme secretion. These studies will be performed on quin-2 loaded acinar cells. Although calcium appears to play an important role during stimulus-secretion coupling, the source of the calcium used to elevate [Ca2+]i and the mechanism by which this calcium is released are unclear. The plasma membrane and the endoplasmic reticulum have been proposed as important calcium-storage locations. Studies described here will investigate this possibility, to include investigation of the mechanism(s) by which calcium is released from these stores. Highly purified membrane vesicle preparations of plasma membrane and endoplasmic reticulum will be prepared from pancreatic acinar cells. Calcium-transport and calcium-stimulated ATPase activity will be characterized in each membrane fraction. Changes occurring in these activities during stimulus-secretion coupling will be examined by the following approaches. First, the effect(s) of secretagogues added directly to the membrane vesicle preparation will be determined. Second, calcium-transport and calcium-stimulated ATPase activity of membranes prepared from cells stimulated by secretagogues will be characterized and compared to control. Finally, the effect(s) of water-soluble inositol phosphates on these activities will be investigated. These compounds have been suggested as the messenger linking secretagogue's plasma membrane receptors to intracellular calcium stores. In additional studies, single channel recordings will be made from membrane fragments inserted in lipid bilayers on patch-clamp pipettes. Any ion channels present will be characterized and the effects of secretagogues and/or water-soluble inositol phosphates on these channels will be determined. The studies described here will further clarify calcium's role in the stimulus-secretion coupling process of pancreatic acinar cells and the mechanism(s) controlling [Ca2+]i during thid process.

二十多年来，有人提出钙充当次级 在刺激 - 分泌耦合期间的使者。 但是，直到最近才有 结果表明，游离胞质钙的浓度（[Ca2+] i）的浓度 促分泌物刺激后，胰腺腺泡细胞增加。 使用钙选择性荧光指示剂quin-2，PI具有 证明[Ca2+]的快速，五倍的增强发生在 激素胆囊分裂素或 卡尔巴乔尔，神经递质乙酰胆碱的类似物。 一个目标 该建议是表征这种瞬态上升的特性 [Ca2+] I并研究其在酶分泌中的作用。 这些研究 将在Quin-2加载的腺泡细胞上进行。 虽然钙出现 为了在刺激 - 分泌耦合期间发挥重要作用， 用于提升[Ca2+] I的钙和该钙的机制 释放尚不清楚。 质膜和内质网 已被提出为重要的钙存储位置。 研究 这里描述的将调查这种可能性，包括调查 从这些商店释放钙的机制。 高度 质膜和内质的纯化膜囊泡制剂 网状会由胰腺腺泡细胞制备。 钙传输 钙刺激的ATPase活性将在每个中表征 膜分数。 在这些活动中发生的变化 刺激分泌耦合将通过以下方法检查。 首先，秘密的效果直接添加到膜上 将确定囊泡的准备。 其次，钙传输和 钙刺激从细胞制备的膜的ATPase活性 由促分子刺激的刺激将被表征并与对照相比。 最后，水溶性肌醇磷酸盐对这些作用 活动将进行调查。 这些化合物已被建议 将秘密质膜受体连接到的使者 细胞内钙存储。 在其他研究中，单个通道 录音将是由插入脂质双层中插入的膜片段制成的 在贴片钳移液器上。 存在的任何离子通道都将被表征 促分子和/或水溶性肌醇磷酸盐的影响 这些渠道将被确定。 这里描述的研究将 进一步阐明钙在刺激 - 分泌耦合过程中的作用 胰腺腺泡细胞和控制[Ca2+] i的机制 过程。