The effect of phlebotomy on canine erythrocyte metabolism.

Enzyme activity declines with erythrocyte age in most mammals. To test this concept in the dog, we decreased the PCV to less than 20 by phlebotomy. The erythrocytes were restored rapidly (1.57 per cent per day). The resulting decline in the mean erythrocyte age was accompanied by increased activity by most of the erythrocyte enzymes studied. Enzymes with lower initial enzymatic activity (hexokinase, pyruvate kinase, 6-phosphogluconate dehydrogenase and glutathione reductase) increased proportionally more than those with higher initial activity (lactate dehydrogenase, 3-phosphoglycerate kinase, glyceraldehyde-3-dehydrogenase and glucose-6-dehydrogenase). Among species, increases in enzyme activity after phlebotomy appear to be related to each species' life span. Most of the metabolites increased concomitantly with the highest reticulocyte period. Diphosphoglycerate concentrations did not change significantly during the experiment.