EFFECT OF ACUTE TRYPANOSOMA-VIVAX INFECTION ON CATTLE ERYTHROCYTE GLUTATHIONE AND SUSCEPTIBILITY TO IN-VITRO PEROXIDATION

During acute Trypanosoma vivax infection of calves, produced by intrav enous inoculation, the mean packed cell volume and red blood cell coun ts of the infected animals decreased significantly (P < 0.05) between Days 6 and 13 post-infection (pi). The moderately severe normocytic an aemia started to develop during the first wave of parasitaemia which o ccurred from Day 2 pi and peaked between Days 4 and 5 pi, The mean ery throcyte glutathione (GSH) concentration of the infected calves decrea sed significantly (P < 0.05) from 58.4 +/- 11.4 mg 100ml(-1) red blood cells (RBC) on Day 0 pi to 44.5 +/- 12.8 mg 100ml(-1) RBC on Day 5 pi . As the GSH values recovered on Day 6 pi and increased thereafter, an other slight decrease (P > 0.05) in GSH concentration occurred on Day 12 pi at the second peak of parasitaemia followed by a significant (P < 0.05) increase to 79.1 +/- 14.6 mg 100ml(-1) RBC on Day 13 pi. In th e uninfected calves, the mean GSH values ranged from 47.7 +/- 7.0 to 6 0.8 +/- 6.8 mg 100ml(-1) RBC. When washed, erythrocytes of the infecte d and uninfected calves were separately challenged with hydrogen perox ide. They produced comparable amounts of thiobarbituric acid reactive substances as a measure of by-products of lipid peroxidation. This sug gested that the ability of the erythrocytes to prevent peroxidative in jury was not reduced, because GSH regeneration was probably enhanced a nd the antioxidant capacity of the erythrocytes was maintained.