Renin response to captopril in conscious dogs pretreated with indomethacin or propranolol

The present experiments were undertaken to examine the involvement of prostaglandins and intrarenal beta-adrenergic system in captopril-induced renin release using conscious dogs. In a first series of experiments, plasma renin activity (PRA) increased 2.5- to 5.2-fold after captopril (1 mg/kg, i.v.) administration. When the same dose of captopril was given in indomethacin (5 mg/kg, i.v.)-pretreated animals, PRA similarly increased. Mean arterial pressure (MAP) and heart rate (HR) were unchanged throughout the experiment in both non- and indomethacin-pretreated animals. In a second series of experiments, captopril-induced PRA elevation was observed under the condition of propranolol (1 mg/kg, i.v.)-pretreatment, although propranolol reduced base line PRA. Statistical analysis did not give a definite evidence that propranolol inhibits captopril-induced renin release. MAP and HR were not changed by captopril in propranolol-pretreated animals as well as in non-pretreated animals. These results suggest that prostaglandins and a real functional interaction with the beta-adrenergic system are not involved in the captopril-induced renin release in conscious dogs.