SECRETORY MECHANISMS IN THE SALIVARY GLANDS

本项目的长期目标是阐明 唾液腺泡细胞的水和电解质分泌。 这种分泌物 反应与信号转导途径有关，该途径涉及 膜磷酸肌醇的周转，Ca2+从 细胞内和细胞外区室和激活的Ca 2 + 单价离子通量（K，C1），这是分泌的关键。 我们的研究 在目前的赠款期间和其他人已经证明， 在这一途径中的复杂功能环节，其中一些只是部分 目前理解的，可能会或可能不会与所有刺激， 促进唾液和电解质的分泌。 信号的一些元素 此外，转导可在唾液细胞中显示独特的特征。 我们 因此，新赠款期的总体目标是探索更大的 详细说明这些功能协会在唾液细胞信号。 我们 具体目标是：1）进一步研究三个之间的耦合 受体类型（胆碱能、α-肾上腺素能和P物质受体 和磷酸肌醇周转。 这种偶联通过GTP结合发生 许多细胞中存在G蛋白，但关于G蛋白的信息很少 在唾液细胞中偶联。 我们将使用免疫沉淀， 放射性配体结合和生物化学方法来鉴定特异性G 与这些受体中的每一个相关的蛋白质，2）表征 进一步研究了钙库和钙通道的功能特性， 机制和方式，他们受到影响的每一种类型的 刺激。 我们将使用荧光光谱成像同位素和x射线 微探针分析技术，以评估细胞内Ca2+的变化， 不存在和存在激动剂以及可以改变 动员内部或外部Ca 2+，3）进一步探索 K和C1电导之间的功能联系和可能的调节 因子，包括[Ca 2 +] i、G蛋白、蛋白激酶和cADP核糖。 我们将使用成像，荧光光谱，同位素和x射线衍射 技术来测量的内容和跨膜通量的变化， 和C1暴露于各种激动剂和所列物质后 以上 我们建议比较这些不同的参数在控制唾液 腺泡细胞和来自长期用药物处理的大鼠的细胞中 （利血平，阿托品），改变受体功能，如图所示。 初步发现，信号通路中的下游元件。 这些 药物治疗导致唾液分泌减少， 研究唾液功能减退及其可能与 改变了信号通路的元素。 口腔干燥症的一个主要原因， 人类是使用药物作为受体拮抗剂和我们的研究 将有助于我们理解正常的唾液信号， 它如何受到治疗剂的影响。

The long-term objective of this project is to elucidate the mechanisms of water and electrolyte secretion in salivary acinar cells. This secretory response is associated with a signal transduction pathway that involves the turnover of membrane phosphoinositides, the mobilization of Ca2+ from intracellular and extracellular compartments and the activation by Ca2+ of monovalent ion fluxes (K, C1) that are critical for secretion. Our studies during the current grant period and those of others have demonstrated complex functional links in this pathway, some of which are only partially understood at present and may or may not operate with all stimuli that enhance salivary fluid and electrolyte secretion. Some elements of signal transduction may show, furthermore, unique features in salivary cells. Our general goal for the new grant period is, therefore, to explore in greater detail these functional associations in salivary cell signaling. Our specific aims are: 1) to investigate further the coupling between three types of receptors (cholinergic, alpha-adrenergic and substance P receptors and phosphoinositide turnover. This coupling occurs by GTP binding proteins in many cells but little information is available about G protein coupling in salivary cells. We will use immunoprecipitation, competitive radioligand binding and biochemical methods to identify the specific G proteins associated with each one of these receptors, 2) to characterize further the functional properties of Ca2+ storage sties and Ca2+ entry mechanisms and the manner in which they are affected by each type of stimulus. We will use spectrofluorimetric, imaging, isotopic and x-ray microprobe analysis techniques to evaluate changes in cell Ca2+ in the absence and presence of agonists and of substances that can modify the mobilization of internal or external Ca2+, 3) to explore further the functional link between K and C1 conductances and possible regulatory factors, including [Ca2+]i, G proteins, protein kinases and cADP ribose. We will use imaging, spectrofluorimetric, isotopic and x-ray diffraction techniques to measure changes in the content and transmembrane fluxes of K and C1 after exposure to the various agonists and of the substances listed above. We propose to compare these various parameters in control salivary acinar cells an in cells derived from rats treated chronically with drugs (reserpine, atropine) that modify receptor functions and, s shown in preliminary findings, downstream elements in the signaling pathway. These drug treatments cause reduced salivary secretion of fluid and are useful models for the study of salivary hypofunction and its possible relation to altered elements of the signaling pathway. A major cause of xerostomia in humans is the use of drugs acting as receptor antagonist and our studies would contribute to our understanding or normal salivary signaling and of how it may be affected by therapeutic agents.