Carbonic anhydrase in rat liver and rabbit skeletal muscle: further evidence for the specificity of the histochemical cobalt-phosphate method of Hansson.

Rat liver and rabbit skeletal muscle were studied by Hansson's method for histochemical demonstration of carbonic anhydrase activity. In histochemical model experiments purified male rat liver carbonic anhydrase was much more resistant to acetazolamide than rat erythrocyte carbonic anhydrase. Male rat liver slices showed cytoplasmic staining, which was about 1000 times more resistant to acetazolamide and ethoxzolamide than that of female rat liver or erthyrocytes of either sex. Rabbit skeletal muscle slices showed staining at the sarcolemma of all fibers, whereas the staining of the sarcoplasm varied. The walls of capillaries situated within the muscle bundles were intensely stained. The sarcoplasmic staining of a certain number of fibers was at least 1000 times less sensitive to acetazolamide than the other staining. These findings, which are in good agreement with biochemical data, show that the sulfonamides inhibit histochemical staining in a specific way. This is strong evidence for the specificity of the method.