ALL NUCLEOSIDE TRANSPORTERS IN BOVINE CHROMAFFIN CELLS ARE NITROBENZYLTHIOINOSINE SENSITIVE

Nitrobenzylthioinosine is an effective inhibitor of adenosine transport in chromaffin cells. When adenosine transport was measured at a 0.15 μM adenosine concentration, in the presence of variable concentrations of nitrobenzylthioinosine, ranging from 10-14 to 10-6 M, a half-maximal inhibitory concentration value (IC50) of 1 ± 0.3 nM was deduced. This compound has the capacity to inhibit the total adenosine transport at 10-7 M concentration. Nitroenzylthioinosine acts in a non-competitive manner in blocking adenosine transport, as deduced from a Dixon plot, with a constant inhibition value (K1) of 0.01 ± 0.003 nM. The results suggest that all nucleoside transporters present in bovine chromaffin cells are sensitive to the nitrobenzylthioinosine inhibition. © 1990.