The relationship between carbonic anhydrase activity and zinc content of erythrocytes in normal,in anemic and other pathologic conditions

A good correlation exists between zinc content and carbonic anhydrase activityof the red blood cells under all conditions studied, including anemia and polycythemia. In almost all patients with anemias other than pernicious anemia, bothzinc and carbonic anhydrase levels were lowered in parallel fashion. These changeswere proportional to decreases in hematocrit and hemoglobin levels and erythrocyte counts so that both zinc and carbonic anhydrase values per unit of RBC werein the normal range. In a few instances of anemia associated with leukemia andin one of sickle cell anemia, neither zinc content nor carbonic anhydrase activitywas decreased in proportion to the anemia; in these cases the zinc and carbonicanhydrase levels per unit of blood were both elevated to the same degree.

Patients with pernicious anemia showed no decrease in absolute values for zincand carbonic anhydrase activity in spite of marked lowering of hematocrit andhemoglobin levels and of erythrocyte count. Accordingly, both zinc concentrationand carbonic anhydrase activity per unit of blood were elevated, often to a markeddegree. These increases were parallel, varying inversely with the degree of anemia;when they regressed under treatment, both did so at the same rate.

There are no methods available for estimating carbonic anhydrase concentration;all methods now in use measure only the activity of the enzyme. It is suggestedthat zinc concentration could be used as an indicator of carbonic anhydrase contentof the red blood cells.

Note: ACKNOWLEDGMENTSDrs. Joseph C. Aub and Ira T. Nathanson were kind enough to refer several patients for study. Dr.Byrl J. Kennedy was most helpful in regard to obtaining samples of blood. The technical work wasperformed by Miss Mary Lou Roney, Betty Hickey and Marion Taylor.