Abstract

Dog and rat liver contain carbonic anhydrase in supernatant and particulate fractions. Hepatic bile of both species has higher HC0₃^- and lower Cl^- concentration than plasma. The enzyme in all fractions of dog liver was inhibited by unsubstituted aromatic sulfonamides at concentrations of 10^-6 to 10^-9 M. In vivo, administration of these drugs at doses which yield > 99% enzyme inhibition lowered biliary HCO₃^- and raised biliary Cl^- concentrations. Certain of the drugs were secreted by liver and concentrated in the bile of both species. Rat liver supernatant carbonic anhydrase was nearly refractory to sulfonamide inhibition in vitro; this is the first example of such lowered response in the animal kingdom. Biliary electrolytes in the rat were accordingly not altered by high doses of these sulfonamides.