The adenosine receptor antagonist, 8-phenyltheophylline, causes diuresis and saliuresis in the rat

The diuretic and adenosine antagonist actions of two alkylxanthines have been compared in the conscious rat. 8-Phenyltheophylline (10 mg kg-1) antagonized adenosine-induced bradycardia in the rat for at least 3 h whereas enprofylline (10 mg kg-1) had no effect on this response. 8-Phenyltheophylline (10 mg kg-1) evoked diuresis and saliuresis in the rat whereas enprofylline (10 mg kg-1) had no effect on excretory parameters. These results indicate that the diuretic action of some alkylxanthines may be related to adenosine antagonism.