SECRETORY MECHANISMS IN THE SALIVARY GLANDS

这个项目的长期总体目标是阐明 唾液及其两种主要分泌物的分泌机制 组分、水/电解质和大分子组分。越多 这项提案中描述的研究的直接目标是 参与该系统形成的离子传输系统 腺泡细胞分泌的初级唾液或前体唾液的液体/电解质部分。 拟议的研究是基于先前的证据表明 唾液主要来源于这些细胞，它的分泌物 被哇巴因和速尿抑制。离子机制的一种模型 唾液分泌的研究被提出，作为第一步， 钠偶联，速尿敏感的氯-进入细胞，这是驱动 由哇巴因敏感的Na，K泵产生的Na梯度。我们 因此，建议使用从大鼠分离的分散的腺泡 颌下腺研究这两种基因的存在和激活 运输系统。具体目标是衡量：1) 钠-22和氯-36的速尿敏感通量。同位素交换和 将测量暴露于胆碱能药物前后的净通量。 肾上腺素能药。哇巴因的影响，离子的变化 孵育介质的组成(Na、Cl、K、Ca)，钙离子载体的组成 A23187，cAMP和cGMP的外源衍生物以及 改变细胞核苷酸含量(如Forskolin和NaNitprusside)将 也被调查。2)H-3哇巴因结合率。时间 半最大值和最大值结合、关联、解离所需 和平衡解离常数(Kd)和结合位密度 (Bmax)将在指定的相同实验条件下进行测量 用于同位素通量。3)哇巴因敏感的Rb-86摄取。摄取率 将在与H-3-哇巴因相同的实验条件下进行测量 有约束力的。这些研究的结果应该提供更直接的证据 对于两个离子传输系统的存在和激活， 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 Cl-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 Cl-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.