SECRETORY MECHANISMS IN THE SALIVARY GLANDS

本项目的长期总体目标是阐明 唾液分泌及其两种主要的 部分、水/电解质和大分子部分。 越 本提案中所述研究的直接目标是表征 离子转运系统参与形成的 腺泡细胞分泌的初级或前体唾液的液体/电解质部分。 拟议的研究是基于以前的证据表明， 唾液主要来源于这些细胞， 被哇巴因和呋塞米抑制 离子机理模型 唾液分泌的建议，涉及，作为第一步， 钠偶联，呋塞米敏感的C1-进入细胞，这是驱动 通过哇巴因敏感的钠钾泵产生的钠梯度。 我们 因此，建议使用从大鼠分离的分散腺泡 下颌下腺研究这两个的存在和激活 运输系统。 具体目标是衡量：1） Na-22和C1-36的呋塞米敏感通量。 同位素交换和 将在暴露于胆碱能物质之前和之后测量净通量， 肾上腺素能药物。 哇巴因的作用， 培养介质、Ca++离子载体的组成（Na、Cl、K、Ca） A23187，cAMP和cGMP的外源性衍生物以及 改变细胞核苷酸含量（如毛喉素和硝普钠）将 也被调查。 2)H-3哇巴因的结合率。 的时间 半最大和最大结合、结合、解离所需 结合位点的平衡解离（KD）常数和密度 （Bmax）将在所示的相同实验条件下测量 同位素通量。 3)哇巴因敏感Rb-86摄取。 吸收率 将在与H-3-哇巴因相同的实验条件下测量 约束力 这些研究的结果应该能提供更直接的证据 两个离子转运系统的存在和激活， 唾液腺泡细胞分泌液体和电解质， 有助于我们理解唾液形成的机制。

The long-term, overall objective of this project is to elucidate the mechanisms underlying the secretion of saliva and of its two major fractions, the water/electrolyte and macromolecular fractions. The more immediate goal of the studies described in this proposal is to characterize the ion transport systems which are involved in the formation of the fluid/electrolyte fraction of primary or precursor saliva by acinar cells. The proposed studies are based on previous evidence indicating that salivary fluid originates primarily in these cells and that its secretion is inhibited by ouabain and by furosemide. A model of the ionic mechanism of salivary fluid secretion is proposed, involving, as a first step, a Na-coupled, furosemide-sensitive C1-entry into the cells, which is driven by the Na gradient generated by an ouabain-sensitive Na, K pump. We propose to use, therefore, dispersed acini isolated from the rat submandibular gland to investigate the presence and activation of these two transport systems. The specific aims are to measure: 1) furosemide-sensitive fluxes of Na-22 and C1-36. Both isotope exchange and net fluxes will be measured before and after exposure to cholinergic and adrenergic agents. The effects of ouabain, of changes in the ionic composition (Na, C1, K, Ca) of the incubation medium, of the Ca++ ionophore A23187, of exogenous derivatives of cAMP and cGMP and of substances which alter cell nucleotide content (such as forskolin and Na nitroprusside) will also be investigated. 2) The rate of binding of H-3 ouabain. The time required for half maximal and maximal binding, association, dissociation and equilibrium dissociation (KD) constants and density of binding sites (Bmax) will be measured under the same experimental conditions indicated for isotope fluxes. 3) Ouabain-sensitive Rb-86 uptake. Rates of uptake will be measured in the same experimental conditions as H-3-ouabain binding. The results of these studies should provide more direct evidence for the presence and activation of two ion transport systems involved in the secretion of fluid and electrolytes by salivary acinar cells and contribute to our understanding of the mechanisms of saliva formation.