Role of extracellular magnesium in insulin secretion from rat insulinoma cells

M. Murakami, J. Ishizuka, S. Sumi, G. A. Nickols, C. W. Cooper, Courtney Townsend, J. C. Thompson

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Abstract

Magnesium (Mg2+) is an abundant intracellular cation that participates in the regulation of the intracellular concentration of ATP. In this study, we examined the relationship between insulin secretion and intracellular free Mg2+ ([Mg2+](i)) in a rat-insulinoma cell line (RIN m5F), using a fluorescent dye (Mag-fura-2). KCl, forskolin, and D-glyceraldehyde increased [Mg2+](i) and insulin secretion from RIN m5F cells in a dose-dependent fashion. Verapamil, a voltage-dependent Ca2+ channel blocker, inhibited the increase of [Mg2+](i) that was evoked by KCl, forskolin, and D- glyceraldehyde. In a Mg2+-free buffer, these agents failed to cause an elevation in [Mg2+](i); however, the insulin response to KCl and forskolin was enhanced, compared with that in the presence of Mg2+ (1.25 mM). Our findings suggest that [Mg2+](i) is dependent upon extracellular Mg2+, and the influx through the voltage-dependent Ca2+ channel. Mg2+ may competitively inhibit the voltage-dependent Ca2+ channel, which is known to play a role in insulin secretion. An absence of Mg2+ in the extracellular space may result in enhanced insulin secretion. [Mg2+](i) may play a role in insulin secretion from RIN m5F cells.

Original languageEnglish (US)
Pages (from-to)490-494
Number of pages5
JournalProceedings of the Society for Experimental Biology and Medicine
Volume200
Issue number4
StatePublished - 1992

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ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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Murakami, M., Ishizuka, J., Sumi, S., Nickols, G. A., Cooper, C. W., Townsend, C., & Thompson, J. C. (1992). Role of extracellular magnesium in insulin secretion from rat insulinoma cells. Proceedings of the Society for Experimental Biology and Medicine, 200(4), 490-494.