UPTAKE OF NUCLEOSIDES BY CELLS IN CULTURE .2. INHIBITION BY 2-MERCAPTO-I-(BETA-4-PYRIDETHYL)BENZIMIDAZOLE

The uptake of radioactive ribo- and deoxyribonucleosides into the acid-soluble and insoluble material of cells was inhibited by 2-mercapto-1-(β-4-pyridethyl)benzimidazole (MPB). The effect was reversible during the first 2-h exposure of cells to the compound. The de novo synthesis of nucleic acids, as measured by 32PO3-4 incorporation, was unaffected during a short-term incubation with MPB although extending the treatment resulted in irreversible damage to cellular viability. It is concluded that MPB inhibits nucleoside uptake and affects cells not by direct inhibition of RNA synthesis but by accumulation of damage at another site. © 1969.