Effect of trasylol on packed cell volume and plasma kallikrein activation in acute Babesia argentina infection of splenectomised calves.

Three groups of four splenectomised calves, three months old, were infected with Babesia argentina parasites. One group was inoculated intravenously with 2000 kallikrein inhibitor units (kiu)/kg body weight of the broad-spectrum proteinase inhibitor, Trasylol, three times a day for 5 days commencing on the 3rd day after infection (early treatment). The same dose of Trasylol was given to a second group for 3 days commencing 8 days after infection (late treatment). The third group was untreated. Parasite multiplication rates were similar in the three groups. In the early treated group levels of activated kallikrein in plasma were significantly lower than those in the other two groups. The early treatment group also showed significantly higher levels of plasma kallikrein inhibitor. No significant differences in total plasma kallikrein levels were seen among the three groups. Packed cell volumes in the treated groups remained significantly higher than those in the controls. The implications of these findings are discussed.