In vivo cell kinetic effects of vincristine on the spontaneous AKR leukemia: recruitment of non-proliferating cells.

In order to investigate the influence of a cell-cycle specific agent on the cytokinetic behavior of a leukemic cell population in vivo, labeling studies with tritiated thymidine (3HTDR) followed by administration of vincristine (VCR) were performed on thymic cells of advanced AKR leukemic mice and evaluated utilizing a combined autoradiographic-Feulgen-microspectrophotometric technique. Twelve hours after a single drug injection the stathmokinetic effect of VCR was observed as reflected by an accumulation of cells in the S/G2-M phase of the mitotic cycle. Within 28 h this effect was no longer evident, but the significant increase in % unlabeled S/G2-M cells strongly suggested an influx of previously non-proliferating cells into the proliferating compartment (recruitment).