Effect of Vincristine on Platelet Production in Mice

Abstract

S ummary Platelet production was investigated using [ 75 Se]selenomethionine bio‐assay in C57BL mice after a single injection of vincristine within the dose range 0.2–3.2 mg/kg. The changes in the circulating platelet count were also followed. There was an immediate, not strictly dose‐dependent, fall in the number of platelets, a quick recovery with an overshoot after small doses, delayed recovery with a moderate overshoot after intermediate doses and a slow recovery returning to normal levels after large doses. The drug caused an overproduction of platelets with every dose used, but this was not necessarily reflected in the peripheral platelet count. It seems unlikely, at least after the smaller doses, that the early fall in platelets plays a role in the increased platelet production. Platelet precursors are resistant to a single dose of vincristine and the drug may have a primary stimulatory effect on the megakaryocytopoietic system.