Hideo Honda, Kiyoshi Yamaguchi and Hiroshi Kogo
Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432 -1, Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract: Female Wistar rats were treated with 17beta-estradiol (E2) (10 microg, s.c.) or with sesame oil for 3 days. The relaxation induced by isoproterenol (10-9-3 x 10-6 M) in aortae precontracted with norepinephrine was significantly suppressed in aortae from E2-treated rats compared with the relaxation in those from control rats. NG-Nitro-L-arginine, a nitric oxide synthase inhibitor, inhibited isoproterenol-induced relaxation in aortae from both E2-treated and control rats. Metyrapone, a cytochrome P-450 monooxygenase inhibitor, inhibited it in aortae from control rats, but metyrapone enhanced the maximum relaxation in aortae from E2-treated rats. These results suggest that E2 modulates isoproterenol-induced vasodilation through nitric oxide and cytochrome P-450-dependent metabolites.
Keywords: Cytochrome P-450, Isoproterenol, 17beta-Estradiol