Abstract
The glycolytic pathway in T.sergenti-parasitized bovine erythrocytes was studied. As the parasitemia of infected calves progressed, the activities of the four enzymes involved in the Embden-Meycrhoff pathway, hexokinase (Hx), phosphofructokinase (PFK), pyruvate kinase (PK) and lactate dehydrogenase (LDH), and the glucose consumption rate increased significantly in all five calves, but not in the erythrocytes obtained from three phlebotomized calves. The enzymes involved in the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G-6-PD) and 6-phosphogluconate dehydrogenase (6-PGD), were unchanged. On the other hand, two intermediate compounds, ATP and GSH varied. ATP levels at the late stage of parasitemia began to vary rapidly (3/5 calves) or decrcased to half of the level of pre-parasitemia. GSH concentrations in 4/5 calves gradually decreased during the course of the parasitemia, but one calf remains unchanged until the end of experiment. In the experiment in which infected cells were fractionated by density gradient, the peaks of the glycolytic enzyme activities except that of G-6-PD, essentially coincided with the peak of the parasitized erythrocytes. It is concluded that the activity of the Embden-Meyerhoff pathway in T.sergenti-parasitized erythrocytes is accelerated, though that of the pentose phosphate pathway remains obscure, and this phenomenon may depend on the glycolytic system of intraerythrocytic protozoa.
