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

• Published in: American journal of obstetrics and gynecology Vol. 181; no. 2; pp. 468 - 476
• Main Authors: Luckas, Murray J.M., Taggart, Michael J., Wray, Susan
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Philadelphia, PA Mosby, Inc 01.08.1999; Elsevier
• 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; myometrium; Agonist; calcium; sarcoplasmic reticulum; Human; Myometrium; Calcium; Arachidonic acid derivatives; Oxytocic; Inductor; In vitro; Contraction; Prostaglandin F2α; Chemotherapy; Carbachol; Female; Influence; Oxytocin(drug); Intracellular; Release
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/S0002-9378(99)70580-6

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.)