Deoxyribonucleoside triphosphate pools and adenosine toxicity

The toxic effect of adenosine on the metabolism of malignant lymphoid cells has been studied in relation to the activity of intracellular adenosine deaminase. Exposure in vitro of L1210 and L5178Y cells for 48 hr to adenosine demonstrated that concentrations above 10^?5 M inhibited cell division, the toxic effect being inversely proportional to intracellular adenosine deaminase levels. Measurement of the deoxyribonucleoside triphosphate pools in cells exposed to adenosine resulted in a 22 per cent reduction in the pyrimidine deoxyribonucleoside triphosphates. Adenosine-mediated growth inhibition was markedly enhanced by coformycin, a potent inhibitor of adenosine deaminase.