Oxytocin-induced phosphorylation of myosin light chain is mediated by extracellular calcium influx in pregnant rat myometrium
✍ Scribed by Hideki Shojo; Yuji Kaneko
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 125 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0952-3499
- DOI
- 10.1002/jmr.551
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✦ Synopsis
Abstract
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.