Intracellular calcium stores and agonist-induced contractions in isolated human myometrium

Objective: We hypothesized that the release of calcium from intracellular stores contributes to the contractions produced by the agonists oxytocin, carbachol, and prostaglandin F 2 α in human myometrium. Study Design: Strips of myometrium were obtained at cesarean section and hysterectomy. The strip...

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Bibliographic Details
Published in:American journal of obstetrics and gynecology 1999-08, Vol.181 (2), p.468-476
Main Authors: Luckas, Murray J.M., Taggart, Michael J., Wray, Susan
Format: Article
Language:English
Subjects:
Adult
Agonist
Biological and medical sciences
calcium
Calcium - analysis
Calcium - metabolism
Carbachol - pharmacology
Dinoprost - pharmacology
Female
Genital system. Reproduction
Humans
Intracellular Fluid - metabolism
Medical sciences
myometrium
Myometrium - drug effects
Myometrium - physiology
Oxytocin - pharmacology
Pharmacology. Drug treatments
Potassium - administration & dosage
Potassium - pharmacology
Pregnancy
sarcoplasmic reticulum
Uterine Contraction - drug effects
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Summary:Objective: We hypothesized that the release of calcium from intracellular stores contributes to the contractions produced by the agonists oxytocin, carbachol, and prostaglandin F 2 α in human myometrium. Study Design: Strips of myometrium were obtained at cesarean section and hysterectomy. The strips were loaded with the calcium-sensitive dye Indo-1 to enable simultaneous measurement of tension and intracellular calcium levels. Agonist-induced responses in the presence and absence of extracellular calcium were studied. Results: Strips of myometrium were obtained from 48 women not in labor undergoing cesarean section and 6 women not pregnant undergoing hysterectomy. An increase in intracellular calcium level after agonist stimulation invariably preceded an increase in tension. Intracellular calcium level returned to baseline before myometrial relaxation. Oxytocin, carbachol, and prostaglandin F 2 α all gave both force and intracellular calcium responses in the absence of extracellular calcium, although both these responses were only 26% to 40% of the maximal response when extracellular calcium was present. Conclusions: Release of calcium from internal stores induced by oxytocin, carbachol, and prostaglandin F 2 α may contribute to agonist-induced myometrial force production. (Am J Obstet Gynecol 1999;181:468-76.)
ISSN:0002-9378
1097-6868
DOI:10.1016/S0002-9378(99)70580-6