Summary.During in vitro incubation in Krebs Ringer phosphate (KRP) medium, rat erythrocytes about 20% parasitized with B. rodhaini used two to four times as much gtucose as unparasitized erythrocytes. However, the ATP concentration and ATP production of parasitized erythrocytes decreased. For example, before incubation the ATP concentration in parasitized erythrocytes was significantly higher than unparasitized erythrocytes, but following 0-5 h incubation it was reduced to about the same as in unparasitized erythrocytes.Addition of 5 X 10-3 M adenosine to the basal medium increased the ATP production and the adenylate energy charge of parasitized erythrocytes. Infectivity tests in susceptible mice showed that, despite these seemingly favourable changes in energy metabolism, adenosine had no detectable effect on the survival of B. rodhaini. Absence of infectivity showed the inability of KRP medium to support B. rodhaini for 22 h in vitro with or without adenosine.Adenosine also greatly decreased the glucose uptake by parasitized erythrocytes, apparently by competitive inhibition, since lactate production was unchanged.
INTRODUCTIONStudies of the metabolism of haemoprotozoan parasites of the genus Babesia are relevant to the production of living vaccines against bovine infections (Callow, 1977). The present series of investigations was designed to study the in vitro metabolism and survival in basal salts media of Babesia rodhaini.Metabolic studies of Babesia rodhaini (Rickard, 1969;Momen, 1979) provided information on the in vitro metabolism, particularly carbohydrate metabolism, of the parasite in basal salts media. There was no information, however, on the in vitro survival or energy metabolism of the parasite in basal media.