Effects of Perfusate HCO3−andPco2on Chloride Uptake in Perfused Gills of Rainbow Trout (Salmo gairdneri)

Publisher Website
Google Scholar
Abstract
Experiments were conducted using a saline-perfused trout (Salmo gairdneri) head preparation in an attempt to determine the origin of HCO3−involved in gill apical Cl−/HCO3−exchange, the possibilities being plasma CO2or HCO3−. Initial results showed that branchial Cl−influx was stimulated both by increased perfusate [HCO3−] and Pco2. Subsequent experiments employing the chloride transport inhibitors, SITS and thiocyanate, indicated that stimulation of Cl−influx by HCO3−probably was due to gill hemodynamic alterations and not to increased entry of HCO3−into the gill epithelium. We conclude that CO2entry into the gill epithelium from plasma and its subsequent hydration to HCO3−and H+, by carbonic anhydrase, is a major pathway by which HCQ3−for Cl−/HCO3−exchange is generated.