Activity of carbonic anhydrase in stored blood

The activity of carbonic anhydrase in blood stored in CPD at 4 degrees C for up to 31 days was measured electrometrically at 5-day intervals and compared with that in fresh blood taken from four normal subjects. No change in activity in stored red cell lysates was observed over this period. There was a clear increase in activity in serum from stored blood with time. These results are discussed in the context of alveolar-to-arterial carbon dioxide gradients seen occasionally in patients following massive transfusions of stored blood.