Human carbonic anhydrases. VI. Levels of isozymes in old and young erythrocytes and in various tissues.

The more acidic, minor isozymes of human carbonic anhydrase types B and C are present in higher concentrations in the older erythrocyte populations. The levels of all of these isozymes can be determined quantitatively by immunochemical methods following their separation by electiofocusing. A wide variety of human tissues have been assayed for carbonic anhydrases. Significant levels of the C type were found in all tissues except cardiac muscle and testis. Carbonic anhydrases of the B type was found only in kidney medulla and gall bladder mucosa.