title: Potassium chloride effects on the hormonal signal transduction mechanisms underlying phasic myometrial contractions.
abstract: These studies sought to test the hypothesis that potassium-stimulated phasic myometrial contractions utilize cytosolic calcium oscillation-like mechanisms comparable to those activated in response to oxytocin. Uterine tissue was obtained from pro-oestrus/oestrus Sprague-Dawley rats. In vitro isometric contraction studies were performed using longitudinal myometrial strips; computer digitalized contraction data were analyzed for contraction area, and normalized for tissue cross-section area. Dose-response studies were performed using potassium chloride with and without inhibitors of cytosolic calcium oscillation mechanisms. Qualitative inositol-phosphate production studies were performed after preloading uterine tissue with [3H]inositol; subsequently, the individual inositol-phosphates produced in response to stimulation were isolated by anion exchange chromatography. Potassium chloride over a concentration of 10 to 30 mM produced a dose-related increase in phasic contractile activity. The potassium-stimulated phasic contractions were significantly suppressed in response to inhibition of phospholipase C, stimulation of protein kinase C, inhibition of calcium-induced calcium release, and prevention of extracellular calcium influx. The qualitative inositol-phosphate production studies confirmed activation of phospholipase C in response to 20 mM potassium. These studies have provided support for the hypothesis that potassium-stimulated phasic myometrial contractions activate intracellular signal transduction mechanisms comparable to those activated in response to hormonal uterotonic agonists.
authors.affiliation: Department of Obstetrics and Gynecology, University of Chicago, Illinois, USA.
authors.forename: M
authors.initials: M
authors.lastname: Phillippe
authors.forename: E K
authors.initials: EK
authors.lastname: Chien
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D007294:Inositol / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D009215:Myometrium / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D013268:Stimulation, Chemical; D010738:Type C Phospholipases / Q000378:metabolism; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D007295:Inositol Phosphates; D007294:Inositol; D011189:Potassium Chloride; D011493:Protein Kinase C; D010738:Type C Phospholipases; D002118:Calcium