IONIC MECHANISMS RELATED TO SECRETION IN PITUITARY CELLS

膜电事件之间的功能耦合的描述 而内分泌细胞分泌激素是 了解内分泌生理学的重要性 腺体 关于参与的离子机制知之甚少， 在这些系统中的兴奋分泌耦合，而不是功能上的 类似于神经末梢释放神经递质分子。 一 增加细胞内钙和 再生电行为是共同的两个过程，但在 激素分泌的情况下，膜离子通道可能负责 对于相关的电行为还有待确定。 的 这项研究的主要目的是表征离子的变化， 由已知的分泌刺激剂和/或抑制剂触发的通道功能 在单个垂体前叶细胞和背侧神经调质 组织培养中的根神经节神经元。 电压钳技术将 使用“千兆密封”方法将这些细胞应用于贴片和整体 手机录音 该项目将侧重于四个要素。 (1)考试 促甲状腺素释放激素（TRH）对 钙激活和电压依赖性钾通道在GH 3细胞中的作用 宏观和单通道电流的测量耦合到 磷脂酰肌醇代谢的操纵。 (2)测定 多种促分泌素对大鼠垂体离子电流的作用 通过梯度分离方法将细胞分离成分泌型。 细胞 将通过免疫细胞化学鉴定类型。 (3)探索机制 参与背根节细胞Ca通道的“下调” 使用细胞内透析和单通道的神经递质 录制. (4)同时测量电活动和激素 使用反向溶血法从培养的单个垂体细胞中释放 在应用促分泌素期间进行噬菌斑测定。 这项研究将导致 更清楚地了解激素背后的分子事件 释放和通道调制。 它还将提供一个框架， 以检查膜的性质和异常与 激素分泌和神经递质释放的病理学。

A description of the functional coupling between membrane electrical events and the exocytotic release of hormones from endocrine cells is of key importance to understanding the physiology of secretion in endocrine glands. Much less is known about the ionic mechanisms involved in excitation-secretion coupling in these systems than about the functionally analogous release of neurotransmitter molecules from nerve terminals. A general requirement for increased intracellular calcium and for regenerative electrical behavior is common to both processes, but in the case of hormone secretion the membrane ionic channels likely responsible for the relevant electrical behavior have yet to be determined. The principle objective of this study is to characterize the changes in ionic channel function triggered by known secretory stimulants and/or inhibitors in individual anterior pituitary cells and by neuromodulators in dorsal root ganglion neurons in tissue culture. The voltage clamp technique will be applied to these cells using "giga-seal" methods for patch and whole cell recording. The project will focus on four elements. (1) Examination of the details of the action of thyrotropin-releasing hormone (TRH) on Ca-activated and voltage-dependent K channels in GH3 cells using measurements of macroscopic and single channel currents coupled to manipulation of phosphotidylinositide metabolism. (2) Determination of the actions of a variety of secretogogues on ionic currents in rat pituitary cells segregated into secretory types by gradient separation methods. Cell types will be identified by immunocytochemistry. (3) Probe the mechanisms involved in "down modulation" of Ca channels in DRG cells by neurotransmitters using intracellular dialysis and single channel recording. (4) Simultaneously measure electrical activity and hormone release from single pituitary cells in culture using a reverse hemolytic plaque assay during application of secretogogues. This research will lead to a clearer understanding of the molecular events underlying hormone release and channel modulation. It will also provide a framework in which to examine membrane properties and abnormalities associated with pathologies of hormone secretion and neurotransmitter release.