Oxytocin increases the [Ca2+](i) sensitivity of human myometrium during the falling phase of phasic contractions
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, MAR 11-14, 1998, ATLANTA, GEORGIA.Full text not available from this repository.
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)|
|Subjects:||R Medicine > RC Internal medicine
Q Science > QP Physiology
|Journal or Publication Title:||AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM|
|Publisher:||AMER PHYSIOLOGICAL SOC|
|Number of Pages:||7|
|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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