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Oxytocin increases the [Ca2+](i) sensitivity of human myometrium during the falling phase of phasic contractions
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UNSPECIFIED (1999) Oxytocin increases the [Ca2+](i) sensitivity of human myometrium during the falling phase of phasic contractions. In: 45th Annual Meeting of the Society-for-Gynecologic-Investigation, ATLANTA, GEORGIA, MAR 11-14, 1998. Published in: AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, 276 (2). E345-E351. ISSN 0193-1849.
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Abstract
Oxytocin is commonly used to induce or augment labor, but its mode of action is uncertain. To address the issue, isometric tension and the intracellular free Ca2+ concentration ([Ca2+](i)) were simultaneously recorded from isolated strips of pregnant human myometrium loaded with fura 2. The changes in [Ca2+](i) and tension during phasic contractions were indistinguishable in myometrium taken before or after the onset of labor, enabling samples to be pooled. Oxytocin (10 nM) had no effect on basal [Ca2+](i) or tension, but it increased both the [Ca2+](i) and the tension recorded during phasic contractions. Analysis of the [Ca2+](i)-tension relationship revealed that during the falling (relaxation) phase of the contractile response, oxytocin increased the tension recorded at each [Ca2+](i). By manipulating extracellular Ca2+ during phasic contractions, it was possible to ensure that the [Ca2+](i) signals were similar in the presence and absence of oxytocin, yet oxytocin still improved the [Ca2+](i)-tension relationship. We conclude that 10 nM oxytocin increases the [Ca2+](i) sensitivity of the contractile proteins only after a contraction has begun, possibly by causing inhibition of myosin light chain phosphatase.
Item Type: | Conference Item (UNSPECIFIED) | ||||
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Subjects: | R Medicine > RC Internal medicine Q Science > QP Physiology |
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Journal or Publication Title: | AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM | ||||
Publisher: | AMER PHYSIOLOGICAL SOC | ||||
ISSN: | 0193-1849 | ||||
Official Date: | February 1999 | ||||
Dates: |
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Volume: | 276 | ||||
Number: | 2 | ||||
Number of Pages: | 7 | ||||
Page Range: | E345-E351 | ||||
Publication Status: | Published | ||||
Title of Event: | 45th Annual Meeting of the Society-for-Gynecologic-Investigation | ||||
Location of Event: | ATLANTA, GEORGIA | ||||
Date(s) of Event: | MAR 11-14, 1998 |
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