CARDIOVASCULAR EFFECTS OF DIHYDRALAZINE, DIAZOXIDE AND MINOXIDIL ALONE OR ASSOCIATED WITH PROPRANOLOL IN RENAL HYPERTENSIVE RATS

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 251  (1) , 103-115
Abstract
Cardiovascular effects after i.v. 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 7 consecutive days with propranolol (5 mg/kg per os). The hypotension induced by the 3 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 3 vasodilators. In the cases of dihydralazine and diazoxide, this effect is due to a lesser decrease of peripheral resistance; with minoxidil, it is due to the absence of decreased cardiac output. Pretreatment of hypertensive rats with propranolol (5 mg/kg per os) for 1 wk 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 i.v. isoprenaline (1-4 .mu.g/kg) was the same in control and propranolol pretreated animals.