Cardiovascular effects of dihydralazine diazoxide and minoxidil alone or associated with propranolol in renal hypertensive rats.
Cardiovascular effects after intravenous administration of dihydralazine (0.5 mg/kg), diazoxide (10 mg/kg) and minoxidil (1 mg/kg) were studied in normotensive (NT) and renal hypertensive rats (HT) pretreated or not for seven consecutive day with propranolol (5 mg/kg per os). The hypotension induced by the three vasodilators in NT and HT rats was caused by decreased peripheral resistance and, in the case of minoxidil in HT rats by decreased cardiac output as well. Propranolol pretreatment of HT rats decreases the hypotensive effect induced by the three vasodilators. In the cases of dihydralazine and diazoxide, this effect is due to a lesser decrease of peripheral resistance; with minoxidil, it results from the absence of decreased cardiac output. Pretreatment of hypertensive rats with propranolol (5 mg/kg per os) for one week had no effect on blood pressure, but decreased heart rate and cardiac output and increased peripheral vascular resistance. Despite these cardiovascular modifications, the reactiveness to intravenous isoprenaline (1 to 4 microgram/kg) was the same in control and propranolol pretreated animals.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D003981:Diazoxide / Q000494:pharmacology; D004078:Dihydralazine / Q000494:pharmacology; D004347:Drug Interactions; D006439:Hemodynamics / Q000187:drug effects*; D006977:Hypertension, Renal / Q000503:physiopathology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008914:Minoxidil / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D000959:Antihypertensive Agents; D008914:Minoxidil; D011433:Propranolol; D007545:Isoproterenol; D003981:Diazoxide; D004078:Dihydralazine