[Effects of some drugs on plasma uric acid in rats--actions of catecholamines and beta-blocking agents]

Effects of catecholamines on plasma uric acid and allantoin levels were studied in oxonate-treated rats and non-treated rats. 1) In non-treated rats, epinephrine, isoproterenol and phenylephrine, which were injected intravenously, clearly increased plasma uric acid and allantoin, and norepinephrine had only a slight effect. The orders of potency to increase plasma uric acid and allantoin were epinephrine greater than isoproterenol greater than phenylephrine greater than norepinephrine. Beta-adrenoceptor agonists also increased plasma uric acid and allantoin in non-treated rats. The order of potency to increase plasma uric acid was isoproterenol salbutamol trimetoquinol greater than terbutaline, and that of potency to increase plasma allantoin was isoproterenol salbutamol greater than or equal to trimetoquinol greater than terbutaline. 2) In oxonate-treated rats, the four beta-adrenoceptor agonists (50 micrograms/kg, i.v.) markedly potentiated the hyperuricemic effect of oxonate. These effects of beta-adrenoceptor agonists were inhibited by propranolol (2.0 mg/kg. i.v.). In addition, the effect of isoproterenol was inhibited by butoxamine (1.0 mg/kg, i.v.), but not by atenolol (1.0 mg/kg, i.v.). These results suggest that hyperuricemia induced by catecholamines is closely related to beta 2-adrenoceptor action.