FLUID AND ELECTROLYTE SECRETION BY PANCREATIC DUCTS

本提案的主要目的是了解 液体和电解质的分泌，由胰腺外分泌。 胰腺 液体和电解质分泌具有腺泡和导管成分， 很可能是通过不同的机制发生的。 此外，分泌 沿着导管树，这种机制可能沿着不同。 有 显著的物种差异;大鼠胰腺代表了一个极端 分泌液中Cl-相对丰富，而豚鼠胰腺 分泌贫Cl-、富HCO 3-的液体。 因此我们建议 利用这些自然发生的变化来识别和 表征负责胰液的关键机制， 电解质分泌 为了实现这一目标，我们制定了 所需的技术：制备孤立的小叶间导管或 无腺泡附着，显微解剖，小叶内灌注 导管和灌注主导管;测量细胞内浓度 和Cl-，H+/HCO 3-和Ca 2+的光子计数从单细胞或 对装载有荧光染料的细胞进行图像采集和分析; 测量由特定转运蛋白介导的离子通量。 我们还 开发了一种新的和简单的技术， 细胞内离子活性和细胞体积的高 时间分辨率 这些技术将用于1）研究和比较 大鼠和豚鼠胰管中的H+/HCO 3-转运机制， 它们通过特定激动剂的调节以及与细胞体积的关系 调控 这些研究的目的是发现积极的机制 负责将HCO 3分泌到导管腔。2)测定Cl- 各种导管（和腺泡）细胞的运输机制。 是 希望我们能够确定积极的机制， 导管细胞的跨上皮Cl-吸收和细胞的基础 和物种变异。3)将酸碱和Cl-转运蛋白定位于 浆膜和/或管腔导管细胞膜。 的 这些研究的目的是开发和测试生理和 腺泡和导管液的解剖学合理模型， 电解质分泌4)细胞体积调节机制的研究 单个胰管（和腺泡）细胞，以了解细胞 体积补偿机制和相互关系 在液体和电解质的整个过程中的转运蛋白 分泌物 我希望拟议的研究将扩大知识 并确定液体和电解质的潜在机制 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.