RUI: Mechanisms of CO2 and Chloride Ion Translocation Across Isolated Perfused Crab Gills

将使用分离的灌流蟹鳃来研究二氧化碳和氯离子通过鳃的转移。通过鳃的二氧化碳通量是一个复杂的过程，原因有几个：1)位于细胞表面和细胞内部的碳酸酐酶，催化二氧化碳的水合和脱水反应；2)二氧化碳是由活跃的代谢过程内源产生的；以及3)水合成碳酸氢盐的二氧化碳通过C1-/HCO3-交换在氯离子吸收中发挥作用。在低盐度胁迫期间，上述过程对动物排泄二氧化碳和吸收氯离子的数量重要性和贡献还知之甚少。这项提案概述了对假设进行测试的实验，这些假设将阐明双重(CO2和C1-)和相关的易位过程。这项研究与任何代谢活跃的上皮细胞的离子摄取过程普遍相关，旨在确定C1-/HCO3-交换器的存在和位置，确定鳃产生的二氧化碳的数量和去向，测量内源性产生的二氧化碳对C1-/HCO3-交换的定量贡献，并测定细胞表面和胞内碳酸酐酶在二氧化碳排泄和氯离子吸收中的定量作用。这些结果对于我们理解正常和污染水域中水生动物的酸平衡、呼吸和离子调节之间的相互作用具有重要意义。

The translocation of CO2 and chloride ions through gills will be studied using isolated perfused crab gills. CO2 flux across the gill is a process which can be complex due to several factors: 1) carbonic anhydrase, which catalyzes the hydration and dehydration reactions of CO2, is located on the cell surface and inside the cell; 2) CO2 is generated endogenously by active metabolic processes; and 3) CO2 hydrated to bicarbonate plays a role in chloride uptake via C1-/HCO3-exchange. The quantitative importance and contribution of the above processes to the excretion of CO2 out of the animal and the uptake of chloride during low salinity stress is poorly understood. This proposal outlines experiments testing hypotheses which will elucidate the dual (CO2 and C1-) and related translocation processes. This study, which has general relevance to ion uptake processes in any metabolically active epithelium, is designed to determine the existence and location of C1-/HCO3-exchanger, determine the amount and the fate of the CO2 produced by the gill, measure the quantitative contribution of endogenously produced CO2 to C1- /HCO3-exchange, and determine the quantitative function of cell surface and intracellular carbonic anhydrase in CO2 excretion and chloride uptake. The results have importance to our understanding of the interplay between acid balance, respiration and ion regulation of aquatic animals in normal and polluted waters.