Mechanisms of Contraction and Relaxation in Human Term Pregnant Myometrium

The study discusses the problem of role of various substances in the mechanisms of contraction and relaxation of human term pregnant myometrium in the experimental in vitro conditions.

Human myometrium tissue samples were collected from term pregnant women who had to undergo Caesarean section. The effects of potassium ion channels openers and closers, phosphodiesterase inhibitors and tachykinins were measured in the reactivity of human term pregnant myometrium in the experimental in vitro conditions.

Specific agonist-opener of K_ATP potassium ion channels - pinacidil significantly reduced contractile activity of human term pregnant myometrial strips induced by administration of oxytocin in in vitro conditions, while the effect of specific agonist-opener of BK_Ca2+ potassium ion channels - NS1619 was not significant. Glibenclamide, specific K_ATP potassium ion channels antagonist-closer significantly increased contractile activity of human term pregnant myometrial strips in in vitro conditions. The contractile effect of specific antagonist-closer of BK_Ca2+ potassium ion channels - tetraethylammonium was not significant. Phosphodiesterase-4 inhibitor - rolipram and phosphodiesterase-5 inhibitor - sildenaphil led to statistically significant decrease of oxytocin-induced contractile activity in human term pregnant myometrial strips in in vitro conditions. Tachykinins - neurokinin A, neurokinin B and substance P markedly stimulated the activity of the human term pregnant myometrial strips in in vitro conditions.

The results showed the different effectiveness of potassium ion channels openers and closers, phosphodiesterase inhibitors as well as tachykinins in the mechanisms of contraction and relaxation of human term pregnant myometrium in in vitro conditions.