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