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

点击翻译按钮获取中文摘要

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.