Oxytocin-induced Ca-free contraction of rat uterine smooth muscle: effects of preincubation with EGTA and drugs.
1. The effect of the time of preincubation with 3 mM EGTA on oxytocin-induced Ca-free contraction of rat uterus was investigated. It was found 10(-2) unit/ml oxytocin induced sustained Ca-free contraction only after preincubation for 50 min or more. 2. The tension developed showed a biphasic relation to the time of preincubation with a minimum at 25 min. 3. Sustained Ca-free contraction could be repeated with only slight reduction in magnitude. 4. Oxytocin-induced Ca-free contraction was relaxed by isoproterenol. The effect of isoproterenol was inhibited by 3 X 10(-4) M 1,1-diphenyl-3-piperazino-1-butanol hydrochloride.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D004347:Drug Interactions; D004533:Egtazic Acid / Q000494:pharmacology*; D005026:Ethylene Glycols / Q000494:pharmacology*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects*
D005026:Ethylene Glycols; D010880:Piperidines; D010121:Oxytocin; D004533:Egtazic Acid; D007545:Isoproterenol; D002118:Calcium