Interactions between magnesium and calcium in β-cell-rich pancreatic islets

P. O. Berggren, P. Bergsten, E. Gylfe

Research output: Contribution to journalArticle

Abstract

Calcium-magnesium interactions, total amounts of intracellular magnesium, and insulin release were studied in β-cell-rich pancreatic islets from ob/ob mice. Mg2+ inhibited the uptake of intracellular 45Ca and insulin release induced by glucose or high concentrations of potassium. Omission of Mg2+ from a Ca2+-deficient medium resulted in an increased efflux of 45Ca, whereas the characteristic glucose inhibition of the efflux was diminished. After addition of Mg2+ to a Mg2+-depleted medium, the glucose-stimulated 45Ca efflux was markedly reduced. Mg2+ inhibited the basal efflux of 45Ca, and this effect was preceded by a transient stimulation. Ca2+ but not Mg2+ stimulated 45Ca efflux in a medium depleted of Ca2+, Mg2+, and Na+. The data indicate that Mg2+ interferes with Ca2+ entry through voltage-dependent Ca2+ channels. Mg2+ may also inhibit the outward transport of Ca2+ from the cells at a site different from the Na+-Ca2+ countertransport mechanism. The total amount of intracellular magnesium remained unaffected by glucose and was not changed unless the ionic composition of the mediums were changed grossly. Under physiological conditions it is therefore unlikely that fluctuations in the intracellular Mg2+ concentration are part of the mechanism by which the functionally important Ca2+ is regulated.

Original languageEnglish
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume7
Issue number6
StatePublished - Jan 1 1983
Externally publishedYes

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Islets of Langerhans
Magnesium
Calcium
Glucose
Insulin
Potassium
Electric potential
Chemical analysis

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology

Cite this

Interactions between magnesium and calcium in β-cell-rich pancreatic islets. / Berggren, P. O.; Bergsten, P.; Gylfe, E.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 7, No. 6, 01.01.1983.

Research output: Contribution to journalArticle

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AB - Calcium-magnesium interactions, total amounts of intracellular magnesium, and insulin release were studied in β-cell-rich pancreatic islets from ob/ob mice. Mg2+ inhibited the uptake of intracellular 45Ca and insulin release induced by glucose or high concentrations of potassium. Omission of Mg2+ from a Ca2+-deficient medium resulted in an increased efflux of 45Ca, whereas the characteristic glucose inhibition of the efflux was diminished. After addition of Mg2+ to a Mg2+-depleted medium, the glucose-stimulated 45Ca efflux was markedly reduced. Mg2+ inhibited the basal efflux of 45Ca, and this effect was preceded by a transient stimulation. Ca2+ but not Mg2+ stimulated 45Ca efflux in a medium depleted of Ca2+, Mg2+, and Na+. The data indicate that Mg2+ interferes with Ca2+ entry through voltage-dependent Ca2+ channels. Mg2+ may also inhibit the outward transport of Ca2+ from the cells at a site different from the Na+-Ca2+ countertransport mechanism. The total amount of intracellular magnesium remained unaffected by glucose and was not changed unless the ionic composition of the mediums were changed grossly. Under physiological conditions it is therefore unlikely that fluctuations in the intracellular Mg2+ concentration are part of the mechanism by which the functionally important Ca2+ is regulated.

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