The Effect of Vincristine on the Platelet Count in Rats

Abstract

S ummary . The effect of vincristine on the platelet count of rats is described. It was found that, depending upon dosage, the drug can cause either a thrombocytosis or marrow hypoplasia with thrombocytopenia in normal rats. Thrombocytosis was found even after prolonged treatment with vincristine when this was given at appropriate dosage. The thrombocytosis promoting effect of the drug was not enhanced by an increase in the splenic platelet pool or decreased by splenectomy. However, it was abolished when prior treatment was given to suppress marrow thrombopoiesis.