To study the possible mechanism of renoprotective effects of adenosine A₁-receptor antagonist against radiocontrast media (RCM)-induced nephropathy, we investigated the effects of adenosine A₁-receptor antagonist on tubuloglomerular feedback (TGF) activity prior to and following application of RCM in chronic NO-depleted rats. TGF in NO-depleted rats was significantly enhanced compared with that in normal rats. After RCM application, the enhanced TGF was continued. A selective adenosine A₁-receptor antagonist, KW-3902 (8-(noradamantan-3-yl)-1, 3-dipropylxanthine), inhibited the enhanced TGF. These results suggest that KW-3902 could inhibit TGF in chronic NO-depleted rats. Renoprotective effects by adenosine antagonists could be partly due to an inhibition of TGF via the blockade of the adenosine A₁-receptor.