Effects of inhibitors of eicosanoid synthesis in the uterus of ovariectomized rats and rats in natural oestrus: relation with calcium

Abstract

1. The effects of 4 inhibitors of eicosanoid synthesis (ESIs)--mepacrine (MEP, 10(-5) - 3 x 10(-4) M), nordihydroguaiaretic acid (NDHGA, 10(-6) - 2 x 10(-5) M), indomethacin (IND, 2 x 10(-6) M and 2 x 10(-5) M) and imidazole (IMI, 10(-5) M and 10(-4) M)--on the motility induced by oxytocin (OT, 0.5 and 4 mU/ml) in uterus of rats in natural oestrus and of ovariectomized rats have been studied. 2. MEP, NDHGA and IND, but not IMI, inhibited the motility induced by both concentrations of OT in natural oestrus. Ovariectomy enhanced the effects of all ESIs, except the one of MEP. 3. MEP and NDHGA, but not IND or IMI, inhibited the contractions induced by methacholine (10(-5) M) and prostaglandin F2a (10(-6) M) and relaxed in a dose-dependent way the tonic component of the contractile response to KCl 60 mM (DI50: 6.14 +/- 0.38 and 1.38 +/- 0.29 x 10(-5) M, respectively). 4. CaCl2 (0.1-10 mM) reverted the relaxation of KCl contractions produced by MEP but not by NDHGA.