In experiments on the isolated ileum of guinea pigs and rats it was shown that 1,3-dipropyl-8-phenylxanthine (DPPX) is a highly potent adenosine antagonist blocking A1-adenosine receptors of the myenteric plexus (pA2 = 7.29 +/- 0.06) and allosterically modulating affinity of A2-receptors of the intestinal smooth muscles to adenosine (pA2 = 6.64 +/- 0.05). DPPX exerted no influence on purinergic (PR2), adrenergic and opiate receptors of the nervous and muscular cells of the intestine. Exceeding the activity of theophylline by 339-87 times, DPPX failed to exert the selective effect on A1- and A2-subtypes of adenosine receptors.