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Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells.

Publication ,  Journal Article
Hurd, WW; Natarajan, V; Fischer, JR; Singh, DM; Gibbs, SG; Fomin, VP
Published in: Am J Obstet Gynecol
August 2002

OBJECTIVE: The purpose of this study was to determine the effects of magnesium sulfate on inositol trisphosphate production and the mechanism of these effects. STUDY DESIGN: Myometrium was obtained at the time of cesarean delivery from women before labor at term. Inositol trisphosphate was measured in the primary myometrial cell cultures after stimulation with oxytocin, sodium fluoride, or Bay K 8644 with or without preincubation with magnesium sulfate or nifedipine. Experiments were performed in either calcium-containing or calcium-free medium that contained egtazic acid and after preincubation with the intracellular calcium chelator BAPTA-acetoxymethylester. Inositol trisphosphate production was measured by radioreceptor assay. In separate experiments, changes in intracellular calcium concentrations ([Ca(2+)](i)) were measured with the use of Fura-2 and spectrophotofluorometry. RESULTS: Oxytocin, sodium fluoride, and Bay K 8644 increased inositol trisphosphate production 2- to 4-fold. Preincubation with magnesium sulfate (3 x 10(-3) mol/L) for > or = 5 minutes decreased oxytocin-, sodium fluoride-, and Bay K 8644-induced inositol trisphosphate production in either calcium-containing or calcium-free media. Preincubation with BAPTA-acetoxymethylester decreased oxytocin-stimulated inositol trisphosphate production by 78% in calcium-containing media and completely prevented the oxytocin response in calcium-free media. Magnesium sulfate decreased inositol trisphosphate production in calcium-containing media but had no additional effect in calcium-free media. Oxytocin and Bay K 8644 increased [Ca(2+)](i) in either calcium-containing or calcium-free media, and magnesium sulfate reduced this in both cases. CONCLUSION: Magnesium sulfate appears to inhibit phosphatidylinositol-4, 5-bisphosphate-specific phospholipase C activity and subsequent calcium release in cultured myometrial cells by a direct effect on phospholipase C.

Duke Scholars

Published In

Am J Obstet Gynecol

DOI

ISSN

0002-9378

Publication Date

August 2002

Volume

187

Issue

2

Start / End Page

419 / 424

Location

United States

Related Subject Headings

  • Sodium Fluoride
  • Oxytocin
  • Obstetrics & Reproductive Medicine
  • Nifedipine
  • Myometrium
  • Magnesium Sulfate
  • Inositol 1,4,5-Trisphosphate
  • Humans
  • Female
  • Egtazic Acid
 

Citation

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MLA
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Hurd, W. W., Natarajan, V., Fischer, J. R., Singh, D. M., Gibbs, S. G., & Fomin, V. P. (2002). Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells. Am J Obstet Gynecol, 187(2), 419–424. https://doi.org/10.1067/mob.2002.123897
Hurd, William W., Viswanathan Natarajan, John R. Fischer, Dawn M. Singh, Shawn G. Gibbs, and Victor P. Fomin. “Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells.Am J Obstet Gynecol 187, no. 2 (August 2002): 419–24. https://doi.org/10.1067/mob.2002.123897.
Hurd WW, Natarajan V, Fischer JR, Singh DM, Gibbs SG, Fomin VP. Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells. Am J Obstet Gynecol. 2002 Aug;187(2):419–24.
Hurd, William W., et al. “Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells.Am J Obstet Gynecol, vol. 187, no. 2, Aug. 2002, pp. 419–24. Pubmed, doi:10.1067/mob.2002.123897.
Hurd WW, Natarajan V, Fischer JR, Singh DM, Gibbs SG, Fomin VP. Magnesium sulfate inhibits the oxytocin-induced production of inositol 1,4,5-trisphosphate in cultured human myometrial cells. Am J Obstet Gynecol. 2002 Aug;187(2):419–424.
Journal cover image

Published In

Am J Obstet Gynecol

DOI

ISSN

0002-9378

Publication Date

August 2002

Volume

187

Issue

2

Start / End Page

419 / 424

Location

United States

Related Subject Headings

  • Sodium Fluoride
  • Oxytocin
  • Obstetrics & Reproductive Medicine
  • Nifedipine
  • Myometrium
  • Magnesium Sulfate
  • Inositol 1,4,5-Trisphosphate
  • Humans
  • Female
  • Egtazic Acid