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Oxytocin‐induced phosphorylation of myosin light chain is mediated by extracellular calcium influx in pregnant rat myometrium
Author(s) -
Shojo Hideki,
Kaneko Yuji
Publication year - 2001
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.551
Subject(s) - oxytocin , myometrium , extracellular , phosphorylation , myosin light chain kinase , verapamil , intracellular , chemistry , signal transduction , medicine , calcium , microbiology and biotechnology , endocrinology , biophysics , biology , biochemistry , uterus
Studies of oxytocin‐induced phosphorylation of myosin light chain (MLC), resulting in myometrial contraction, suggest that extracellular Ca 2+ influx is involved in its signal transduction. To explore the possibility that intracellular Ca 2+ mobilization by oxytocin may also contribute to MLC phosphorylation, we investigated the relative contributions of these Ca 2+ sources to oxytocin signal transduction in myometrium of pregnant rat. In pregnant rat myometrium, oxytocin‐induced Ca 2+ influx occurs via an L‐type voltage‐dependent Ca 2+ channel. Treatment with verapamil, an antagonist specific for these channels, significantly diminished MLC phosphorylation observed in response to oxytocin administration without affecting the release of Ca 2+ from intracellular Ca 2+ stores. Furthermore, oxytocin‐induced MLC phosphorylation was not observed when extracellular Ca 2+ was not present. Our results clearly indicate that extracellular Ca 2+ influx, rather than release from Ca 2+ storage sites, is essential for oxytocin‐induced MLC phosphorylation. Copyright © 2001 John Wiley & Sons, Ltd.