Dipyridamole suppresses uptake of thymidine in human and bovine cells in vitro.

Dipyridamole has been shown to induce proliferative activity in heart muscle capillary wall cells in the rat. To test whether this effect is due to direct cellular stimulation we tested the substance in various in vitro systems (human lymphocytes, glial cells and endothelial cells; and bovine endothelial cells). During these conditions dipyridamole did not influence cellular proliferation. In all cell systems tested, uptake of labelled thymidine showed an inhibition by dipyridamole. This confirms the earlier finding that dipyridamole inhibits nucleoside uptake, and extends the finding to human cells.