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 language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the Society for Experimental Biology and Medicine|
|State||Published - 1992|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)