RAPID CHANGES IN NUCLEOSIDE TRANSPORT INDUCED BY GROWTH INHIBITORS : Studies with Neoplastic Mast Cells

Aqueous extracts of murine embryonic or uterine tissue, or [⁶N]O²'-dibutyryl 3',5'-adenosine monophosphate (dbc-AMP) which were cytostatic for the murine mastocytoma P815Y in vitro also induced rapid changes in the incorporation of exogenous nucleosides into acid-insoluble material. However, these alterations were not a consequence of growth arrest. Different dose-response curves were obtained for cytostasis and inhibition of [³H]-nucleoside incorporation, and changes in [³H]thymidine uptake were detected within 15 min of treatment with the inhibitors. Also, there were differential effects of each inhibitor on the incorporation of ³H-labeled thymidine, uridine, adenosine, or choline into acid-insoluble material.