[Effect of methylxanthines on urinary prostaglandin E excretion of rats acutely loaded with salt and water (author's transl)].

The effect of methylxanthines (theophylline, theobromine, caffeine) on urinary prostaglandin E (PGE) excretion in rats was investigated. Male rats, weighing 270-300g only were used. Food was withdrawn 3 hr before the experiment and water intake was free during the test period. In saline or water loaded experiments, 0.9%, 9% NaCl solution or water containing each drug was administered orally in a volume of 2.5 ml/100g. The urinary PGE was measured by bioassay using rat stomach fundus strip. In rats loaded with isotonic saline, the urinary PGE excretion was increased by methylxanthines and the greatest effect was seen with theophylline. The effect of theophylline on PGE excretion was evident in non-loaded and isotonic saline-loaded rats. In particular, the percentages of PGE, sodium and chloride in the urine were remarkably increased, as compared with findings in the control. In non-loaded and isotonic saline-loaded rats, the urinary PGE excretion induced by theophylline correlated significantly with the sodium and chloride excretion. These results suggest the participation of renal PGE in the effects of theophylline on kidney function.