Carbonic anhydrase activity and erythrocyte count in the blood of zinc-deficient rats.

Eighteen male Sprague Dawley rats were divided into three groups. They were offered a semisynthetic casein diet containing either 1.2 mg Zn/kg dry matter (depletion group) or 100 mg Zn/kg dry matter (ad libitum and pair-fed control groups). At the beginning and on the 5th and 24th day of the experiment, blood was removed from a tail vein by incision to determine erythrocyte count and carbonic anhydrase activity. The zinc-depleted animals displayed a great increase in erythrocytes during the course of the experiment as compared to the ad libitum control animals. The erythrocyte counts of the pair-fed animals were also increased after 24 days on experiment, but remained significantly lower than those of the depleted animals. The activity of the carbonic anhydrase per ml blood was the same in all groups at the end of the experiment. When, however, the carbonic anhydrase activity was expressed per unit of erythrocytes, the zinc-deficient animals had a significantly lower enzyme activity than both the ad libitum and the pair-fed control rats.