Amphotericin B renders stationary phase hepatoma cells sensitive to dipyridamole

This study provides evidence that the dipyridamole inhibitory effect on nucleoside incorporation changed with culture time. Lag and log phase hepatoma 3924A cells were highly sensitive to dipyridamole with IC50 values for thymidine incorporation of 0.20 and 0.31 microM, respectively. In contrast, stationary phase cells were comparatively insensitive to dipyridamole with an IC50 of 38.9 microM. Amphotericin B (10 microM) restored the sensitivity of stationary phase cells to dipyridamole, lowering the IC50 value for thymidine incorporation to 0.25 microM. Amphotericin B also enhanced the cytotoxicity of dipyridamole to hepatoma 3924A cells. The combination of amphotericin B and dipyridamole may be useful in cancer chemotherapy.