FLUID AND ELECTROLYTE SECRETION BY PANCREATIC DUCTS

这项建议的主要目标是了解 体液和电解质的分泌，由胰腺外分泌。胰腺 液体和电解质分泌物有腺泡和导管成分， 很可能是通过不同的机制发生的。此外，分泌物 机制可能在导管树上有所不同。确实有 显著的物种变异性；大鼠胰腺代表一个极端 分泌相对富含氯离子的分泌液，而豚鼠胰腺 分泌富含HCO3-的贫氯液体。因此，我们建议 利用这些自然产生的变异来识别和 描述导致胰腺积液的主要机制和 电解质分泌。为了实现这一目标，我们发展了 所需的技术：准备隔离小叶间导管或 未附着腺泡，显微解剖，小叶内灌流 管道，并灌流主管道；测量细胞内浓度 用单细胞或单细胞的光子计数测定和Cl-，H+/HCO3-和Ca2+ 荧光染料负载细胞的图像采集和分析； 测量特定转运体介导的离子通量。我们还有 开发了一种新的简单的技术来同时记录 高密度脂蛋白单细胞内离子活度和细胞体积 时间分辨率。这些技术将被用于1)研究和比较 H+/HCO3-在大鼠和豚鼠胰管中的转运机制， 它们受特定激动剂的调节及其与细胞体积的关系 监管。这些研究的目的是为了发现它们的活性机制。 负责将HCO3-分泌到管腔。2)测定氯离子 各种导管(和腺泡)细胞的运输机制。它是 希望我们能够确定活跃的机制 跨上皮细胞对氯离子的吸收及其细胞基础 以及物种的变异。3)将酸碱和氯离子转运蛋白定位到 使用灌流导管的浆膜和/或腔内导管细胞膜。这个 这些研究的目的是开发和测试生理和 腺泡和导管流体的热力学模型和 电解质分泌。4)细胞体积调节机制的研究。 了解单个胰管(和腺泡)细胞 体积补偿机制及其相互关系 液体和电解液整个过程中的转运体 分泌物。我希望拟议的研究将扩大这一知识 并确定流体和电解液的潜在机制 胰腺外分泌的分泌物。

The principal objective of this proposal is to understand the mechanisms of fluid and electrolyte secretion, by the exocrine pancreas. Pancreatic fluid and electrolyte secretion has an acinar and ductal components which most probably occur by different mechanisms. In addition, the secretory mechanism is likely to differ along the ductal tree. There are significant species variability; the rat pancreas represents one extreme secreting fluid relatively rich in Cl- whereas the guinea pig pancreas secretes fluid poor in Cl- and rich in HCO3-. We therefore propose to make use of these naturally occurring variabilities to identify and characterize the key mechanisms responsible for pancreatic fluid and electrolyte secretion. Towards achieving this goal, we have developed the techniques required to: prepare isolated interlobular ducts with or without acini attached to them, microdissect and perfuse intralobular ducts, and perfuse main ducts; measure the intracellular concentrations of and Cl-, H+/HCO3- and Ca 2+ using photon counting from single cells or image acquisition and analysis of cells loaded with fluorescent dyes; measure ion fluxes mediated by specific transporters. We have also developed a new and simple technique for the simultaneous recording of intracellular ionic activities and cell volume of single cells with high time resolution. These techniques will be used to 1) Study and compare H+/HCO3- transport mechanisms in rat and guinea pig pancreatic ducts, their regulation by specific agonists and relation to cell volume regulation. These studies are aimed at discovering the active mechanisms responsible for HCO3- secretion to the duct lumen. 2) Determine Cl- transport mechanisms by the various ductal (and acinar) cells. It is hoped that we will be able to determine the mechanism of active transepithelial Cl- absorption by duct cells and the basis for cellular and species variations. 3) Localize acid base and Cl- transporters to the serosal and/or luminal ductal cell membranes using perfused ducts. The purpose of these studies is to develop and test physiologically and thermodynamically sound models for acinar and ductal fluid and electrolyte secretion. 4) Study mechanisms of cell volume regulation in single pancreatic duct (and acinar) cells to understand the cellular volume compensatory mechanism and interrelationships between the transporters during the overall process of fluid and electrolyte secretion. I hope that the proposed studies will extend the knowledge and determine the underlying mechanisms of fluid and electrolyte secretion by the exocrine pancreas.