The accumulation of [ 3H]phenylisopropyl adenosine ([ 3H]PIA) and [ 3H]adenosine into rabbit retinal neurons is inhibited by nitrobenzylthioinosine (NBI)

Uptake of [ 3H]adenosine and [ 3H] R-phenylisopropyladenosine ( R-PIA) into retinal cells was assessed autoradiographically, in the presence and absence of the purine nucleoside transport inhibitor, nitrobenzylthioinosine (NBI). Under control conditions, both purine nucleosides were accumulated in cell bodies localized to the ganglion cell layer, and the inner nuclear layer. In the presence of NBI, significantly less accumulation of nucleosides within cell bodies was observed, particularly within the inner nuclear layer, suggesting that most of the uptake occured via the transport of both substrates. The stereoisomer of adenosine, l-[ 3H]adenosine, was not accumulated into retinal cells consistent with the view that the accumulation of both adenosine and R-PIA occurs via the purine nucleoside transporter.