Effects of highly concentrated estrogen and progesterone on the contractile mechanism of the uterine smooth muscles

Abstract

The effects of a high concentrated estrogen and progesterone were studied on the contractile activities in isolated myometrial strips from humans and rats by recording isometric tension development. The contractions were reduced by 10(-5)-3 X 10(-5) M estrone (E1), estradiol (E2), estriol (E3), and progesterone (P) in non pregnant human uterus. The contractions were reduced by 10(-6)-10(-4) M E1, E2, E3 and P in non pregnant rat uterus. The contractions induced by 10(-8)-10(-5) M PGE2 and PGF2 alpha were reduced by 10(-5) M E2 and P in non pregnant rat uterus. The contractions induced by 10(-10)-3 X 10(-8) M oxytocin were reduced by 10(-5) M E2 and P in non pregnant rat uterus. The contractures induced by 10(-4)-10(-2) M Ca2+ were reduced by 10(-5) M E2 and P in non pregnant rat uterus. The effects of a high concentrated estrogen and progesterone were studied on Ca2+ influx and Ca2+ release from intracellular Ca store in the depolarized uterine smooth muscle cells from non pregnant rats. The inhibitory effects on the contractility by 3 X 10(-6)-3 X 10(-5) M E2, E3 and P supported the suggestion that estrogen and progesterone have an inhibitory action on Ca2+ influx and Ca2+ release from intracellular Ca store.