Turnover of purine nucleotides in rabbit erythrocytes: lack of in vivo effect of the nucleoside transport inhibitor, p-nitrobenzyl-6-thioguanosine.

Abstract

The turnover of purine nucleotides in rabbit erythrocytes in vivo was studied by following the decline with time in the erythrocyte content of 14C-purine metabolites; the half-times of 14C-metabolites of adenine-8-14C and guanine-8-14C were about 30 h and 6 h, respectively. The possibility that purine nucleosides external to the erythrocyte might be involved in nucleotide turnover was tested in experiments which measured the effect on turnover of the inhibitor of nucleoside transport, p-nitrobenzyl-6-thioguanosine. This compound profoundly inhibited a transport-dependent aspect of nucleoside metabolism in erythrocytes, the formation of inosine from externally provided hypoxanthine and guanosine. However, only minor effects on turnover of labelled purine metabolites resulted from treatment of erythrocytes either in vitro or in vivo with the nucleoside transport inhibitor. Multiple intravenous injections of the inhibitor blocked nucleoside transport in erythrocytes, but had only minor effects on the turnover of metabolites of adenine and guanine. It is concluded that purine nucleosides per se are not importantly involved in the turnover of erythrocyte nucleotide pools.