Inhibition of uridine incorporation into rna in mammalian cells by agents affecting the properties of the cell membrane: Chloropromazine, dipyridamole and phenylethanol

Abstract The effects of chloropromazine, dipyridamole and 2-phenylethanol on the permeability of the cell membrane and on the metabolism of exogenous uridine by Ehrlich ascites cells were compared, by following the rate of fluorescein efflux from the cells, the incorporation of the labelled nucleoside into RNA and by determining the distribution of the label between the various metabolites. The main effect of chloropromazine was on the passive permeability of the cell membrane, decreasing it at low concentration and increasing it at higher ones; the latter effect was enhanced by irradiation with visible light. Dipyridamole did not modify the passive permeability, but blocked the entry of the nucleoside into the cell. Phenylethanol inhibited the entry of the nucleoside and increased the cell permeability.