Radiographic contrast media (CM) can induce renal failure and this may serve as an experimental model of acute renal failure (ARF). One vasoactive factor likely to be involved in ARF is adenosine. In a double-blind, placebo-controlled study we investigated the effect of theophylline (TP), an adenosine receptor antagonist, regarding changes in renal hemodynamics induced by CM. Thirty-nine patients who received 100 ml of a non-ionic low osmolar CM (iopromide) were studied for changes in GFR and RPF by continuous inulin and PAH clearance before and until four hours after CM application. Forty-five minutes before the application of CM, patients were randomized and received either theophylline (5 mg/kg body wt) or the vehicle and placebo (saline) intravenously in a blinded manner. We additionally measured the creatinine clearance on the day before and two days after CM application. Sodium excretion, N-acetyl-beta-glucosaminidase (NAG) excretion, plasma renin activity (PRA) and aldosterone levels were also measured before and after CM application. Theophylline levels were within the therapeutic range in patients of the theophylline group during and four hours after CM application (59.0 +/- 10.6 mumol/liter and 40.1 +/- 10.9 mumol/liter). GFR, measured by inulin clearance significantly declined under CM application in patients without TP application (N = 19; 88 +/- 40 to 75 +/- 32 ml/min/1.72 m2; P < 0.01). In the group of patients receiving theophylline (N = 18) the GFR remained constant (75 +/- 26 vs. 78 +/- 33 ml/min/1.72 m2).(ABSTRACT TRUNCATED AT 250 WORDS)