Depressor mechanism of enalapril in rats made hypertensive by norepinephrine or vasopressin.
We evaluated the antihypertensive mechanism of enalapril, a long-lasting inhibitor of angiotensin-converting enzyme, in rats made hypertensive by chronic infusion of norepinephrine or vasopressin. The hypertensive effect of norepinephrine (1.8 mg/kg/day intraperitoneal (i.p.] or vasopressin (7.2 U/kg/day i.p.) was completely abolished by simultaneous administration of enalapril (6 mg/kg/day i.p.). The antihypertensive effect of enalapril was not reversed by simultaneous administration of subpressor doses of angiotensin II (36 and 100 micrograms/kg/day i.p.). However, the hypertensive effects of angiotensin II at pressor doses (600 and 900 micrograms/kg/day i.p.) in enalapril-infused rats were not different from those in vehicle-infused rats. These results indicate that the hypotensive effect of enalapril may in part depend on a reduced sensitivity of the vasculature to norepinephrine and vasopressin, independent of inhibition of angiotensin II formation.
Yasujima
M
M
Second Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Abe
K
K
Tanno
M
M
Kanazawa
M
M
Yoshida
K
K
Sato
M
M
Takeuchi
K
K
Yoshinaga
K
K
D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004359:Drug Therapy, Combination; D004656:Enalapril / Q000008:administration & dosage / Q000494:pharmacology*; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy*; D007274:Injections, Intraperitoneal; D008297:Male; D009638:Norepinephrine; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins
D014667:Vasopressins; D000804:Angiotensin II; D004656:Enalapril; D009638:Norepinephrine