PHYSIOLOGY OF THE ISOLATED MAMMALIAN PARIETAL CELL

由血液、神经和局部组织传递的几种化学信使 胃底粘膜的贮液调节酸的分泌。 该补助金的目的是 是为了识别壁细胞和旁分泌细胞上的受体 负责酸分泌的刺激和抑制调节。 这项更新建议的重点是壁细胞的直接调节剂 (PC)功能 膳食刺激胃酸分泌的主要决定因素 是消化的肽和氨基酸（AA）。 AA刺激酸分泌 通过胃泌素的释放和对胃底粘膜的直接作用， 其机制尚未确定。 我们的提议是 催化的初步发现，3支链AA（支链氨基酸）， 亮氨酸，缬氨酸和异亮氨酸，显着增强功能的分离 犬PC。 我们的初步数据表明，这些支链氨基酸可能是 调节剂或必要的允许因子的犬PC反应， 其他Secretagogues 我们的总体目标是了解这些行为 PC上的BCAA是生理相关的，并定义可能的 这些底物诱导其功能效应的机制。 我们 将研究BCAA的立体特异性、剂量反应和时间过程 刺激PC功能。 我们将比较BCAA对14 C的影响- 氨基比林积累、形态转化和氧 消费 我们将继续进行初步调查， 内源性BCAA抑制PC对其他促分泌素的反应。 我们将 通过以下方式检验AA通过L-系统转运是限速的假设： 利用选择性抑制剂和竞争底物， 功能和摄取放射性标记的AA。 我们将比较 高度富集的PC和主细胞，以确定PC BCAA摄取是否 独特. 我们将确定BCAA的代谢是否是BCAA所必需的 刺激，比较代谢率与功能反应。 我们将 测试BCAA增强反映细胞扩增的可能性， 激活信号，研究支链氨基酸对环磷酸腺苷生成的影响， 磷脂酰肌醇分解和细胞溶质钙信号单独和 与其他刺激的组合。 BCAA对Na+/H+逆向转运蛋白的影响 将评估BCAA对蛋白质磷酸化的影响。 这些 研究将阐明AA对PC功能的直接影响，并可能提供 深入了解营养素调节细胞功能的基本机制。

Several chemical messengers delivered by blood, nerves, and local tissue stores to the fundic mucosa regulate acid secretion. The aim of this grant has been to identify the receptors on parietal and paracrine cells responsible for stimulatory and inhibitory modulation of acid secretion. This renewal proposal is focused upon direct modulators of parietal cell (PC) function. The major determinants of meal-stimulated acid secretion are digested peptides and amino acids (AA). AA stimulate acid secretion via both release of gastrin and direct effects on the fundic mucosa, the mechanisms of which have not been identified. Our proposal has been catalyzed by preliminary findings that the 3 branched chain AA (BCAA), leucine, valine, and isoleucine, markedly enhance the function of isolated canine PC. Our preliminary data suggest that these BCAA may either be modulators or necessary permissive factors for the canine PC response to other secretagogues. Our overall goal is to learn whether action of these BCAA on PC is physiologically relevant and to define the possible mechanisms by which these substrates induce their function effects. We will study the stereospecificity, dose response, and time course for BCAA stimulation of PC function. We will compare the effects of BCAA on 14C- aminopyrine accumulation, morphological transformation, and oxygen consumption. We will pursue our preliminary finding that depletion of endogenous BCAA depresses the PC response to other secretagogues. We will test the hypothesis that AA transport via the L-system is rate-limiting by utilizing selective inhibitors and competing substrates testing both function and uptake radiolabelled AA. We will compare uptake between highly enriched PC and chief cells to determine if PC BCAA uptake is unique. We will determine if metabolism of BCAA is necessary for BCAA stimulation, comparing metabolic rates with functional responses. We will test the possibility that BCAA enhancement reflects amplification of cell activation signals, studying BCAA effects on cyclic AMP generation, phophotidylinositol breakdown and cytosolic calcium signals alone and in combinations with other stimuli. BCAA effects on the Na+/H+ antiporter will be evaluated as will BCAA effects on protein phosphorylation. These studies will elucidate direct AA effects on PC function and may provide insight into basic mechanisms by which nutrients modulate cell function.