PHYSIOLOGY OF THE ISOLATED MAMMALIAN PARIETAL CELL

几种由血液、神经和局部组织传递的化学信使 胃底粘膜的储存物调节胃酸的分泌。这笔赠款的目的是 已经确定了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器 (PC)功能。饮食刺激胃酸分泌的主要决定因素 是被消化的多肽和氨基酸(AA)。AA刺激胃酸分泌 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。我们的建议一直是 催化的初步发现是3个支链AA(BCAA)， 亮氨酸、缬氨酸和异亮氨酸，显著增强分离的 犬类电脑。我们的初步数据表明，这些支链氨基酸可能是 犬PC反应所需的调节剂或必要的允许因子 其他的偷偷摸摸。我们的总体目标是了解这些行动是否 PC上的支链氨基酸是生理上相关的，并定义了可能的 这些底物诱导其功能效应的机制。我们 将研究支链氨基酸的立体特异性、剂量反应和时间过程 刺激PC功能。我们将比较支链氨基酸对~(14)C的影响。 氨基比林的蓄积、形态转化和氧气 消费。我们将继续调查我们的初步调查结果 内源性支链氨基酸抑制PC对其他促分泌剂的反应。我们会 通过以下方式测试AA通过L系统传输是限速的假设 利用选择性抑制剂和竞争底物测试两者 功能和摄取放射性标记的AA。我们将比较这两种情况 高度浓缩PC和主细胞以确定PC BCAA摄取是否 独一无二。我们将确定支链氨基酸的代谢是否是支链氨基酸所必需的 刺激，将代谢率与功能反应进行比较。我们会 检测支链氨基酸增强反应细胞扩增的可能性 激活信号，研究支链氨基酸对环状AMP生成的影响， 磷脂酰肌醇分解和胞浆钙信号单独和在 与其他刺激物的组合。支链氨基酸对Na~+/H~+逆向转运蛋白的影响 将评估支链氨基酸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 深入了解营养物质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.