CARBOHYDRATE METABOLISM IN BABESIA RODHAINI - DIFFERENCES IN METABOLISM OF NORMAL AND INFECTED RAT ERYTHROCYTES

Glucose metabolism in rat erythrocytes appeared to be qualitatively similar to that reported for the erythrocytes of other mammalian species, although the rates of oxygen uptake and glucose utilization were greater than those of the erythrocytes of larger animals. Erythrocytes incubated with excess glucose as substrate had a high equilibrium ratio of pyruvate to lactate, which may have been due to high rates of NADH-dependent methemoglobin reductase activity. When rat erythrocytes were deprived of substrate they continued to respire at a constant rate for at least 2 hours; there was a marked accumulation of pyruvate during this period. Increased reticulocyte percentage in rats' blood led to increased respiratory and glycolytic rates. There was a high positive correlation between reticulocyte percentage and oxygen uptake. B. rodhaini-infected rat erythrocytes exhibited rates of oxygen uptake and glycolysis far in excess of normal rat erythrocytes. However, the ratio of oxygen uptake to glucose utilization was no greater than that in normal rat erythrocytes, and less than that reported for erythrocytes infected with Plasmodium spp., suggesting, therefore, a greater dependence of B. rodhaini on anaerobic metabolism. Lactate was always the major end product of glucose metabolism in B. rodhaini-infected red blood cells. The glycolytic ratios, and the percentages of glucose which could be accounted for as oxygen uptake, lactate, and pyruvate, indicated a greater use of glucose for synthetic purposes in infected cells when compared with normal rat erythrocytes. When the parasite was within its host erythrocyte, it continued to respire and produce lactate and pyruvate for some hours in the absence of added substrate. © 1969.