Human carbonic anhydrase I concentration in erythrocytes during pregnancy and the menstrual cycle.

Carbonic anhydrase I (HCAI) concentrations were measured in erythrocytes (RBC) taken from nine women at intervals throughout their pregnancies and from thirteen normal women during the menstrual cycle. No significant changes in RBC HCAI concentrations were found in any instance. Small changes which were found in RBC HCAI concentrations were within experimental error and did not correlate with any other measured parameter. Changes in RBC HCAI concentrations in six men over a four-week period were of similar order to that found in the thirteen normal women over a similar length of time.