Role of Extracellular Magnesium in Insulin Secretion from Rat Insulinoma Cells

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

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


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). KCI, 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 KCI, forskolin, and D-glyceraldehyde. In a Mg2+-free buffer, these agents failed to cause an elevation in [Mg2+]i; however, the insulin response to KCI 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
Issue number4
StatePublished - Sep 1992
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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