HORMONE REGULATION OF CA2+ IN PANCREATIC ACINAR CELLS

这项计划的主要目的是扩大我们对 钙激活激素对心肌细胞钙离子通透性和细胞周期的影响 胰腺腺泡细胞内的钙离子泵。 这构成了理解 细胞内贮藏物的释放和重新装载机制 通过钙离子对Upton细胞的刺激和去除刺激物。到目前为止， 我们已经开发了测量细胞内游离钙离子的技术 用钙敏感染料Fura检测完整的胰腺腺泡细胞 2.专门标记激素可动员的胞内池 在完整细胞内有45Ca；测定钙离子通道介导的- ~(45)Ca在完整和通透性细胞中的通量；并测量 Ca~(2+)泵介导的通透性细胞内~(45)Ca通量。vbl.使用 这些技术的直接目的是(A)证明 从胞内池中释放出的钙足以激活 质膜钙通道。此通道的激活是 不直接调解，并且不需要 荷尔蒙。(B)证明荷尔蒙，如IP3，能激活钙离子 内质网膜上的通道。(C)比较 IP3、GTP和花生四烯酸对激素的影响 激活细胞内池中钙离子的释放。(D)研究 IP3、GTP和花生四烯酸对激素的贡献 依赖性钙离子释放(E)定义了新的 发现，内质网钙泵被激活 通过钙离子动员激素(F)试图表征 内质网钙泵的激活机制 通过钙离子动员激素的钙泵作用。 我们的基础研究提供了检验假设的技术 细胞内游离钙和钙离子含量的激素调节 胰腺腺泡细胞的细胞内储存 在细胞刺激终止时。

The principal object of this project is to extend our studies on the effect of Ca2+ mobilizing hormones on the Ca2+ permeability and Ca2+ pump of the intracellular stores of pancreatic acinar cells. This constitutes as essential stage towards understanding the mechanisms of release and reloading of the intracellular stores with Ca2+upton cell stimulation and removal of stimuli. To date, we have developed techniques; to measure free cytosolic Ca2+ in intact pancreatic acinar cells using the Ca2+ sensitive dye FURA 2; to specifically label the hormone mobilizable intracellular pool with 45Ca in intact cells; to measure Ca2+ channel mediated - 45Ca fluxes in intact and permeabilized cells; and to measure Ca2+ pump mediated -45Ca fluxes in permeabilized cells. Using these techniques, the immediate aims are (a) demonstration that Ca2+ release from the intracellular pool is sufficient to activate the plasma membrane Ca2+ channel. Activation of this channel is not directly mediated and does not require the presence of the hormone. (b) Show that the hormone, like IP3, activates a Ca2+ channel in the endoplasmic reticulum membrane. (c) Compare the effects of IP3, GTP and arachidonic acid with the hormone activated Ca2+ release from the intracellular pool. (d) Study the contribution of IP3, GTP and arachidonic acid to the hormone dependent Ca2+ release (e) define the requirements for the newly discovered, activation of the endoplasmic reticulum Ca2+ pump by the Ca2+ mobilizing hormone (f) attempt to characterize the mechanism of activation of the endoplasmic reticulum Ca2+ pump by the Ca2+ pump by the Ca2+ mobilizing hormones. Our basic studies are providing techniques to test hypotheses on hormonal regulation of free cytosolic Ca2+ and Ca2+ content in the intracellular stores of pancreatic acinar cells both during and at the termination of cell stimulation.