PMID: 6162455Aug 15, 1980Paper

Calcium and pancreatic beta-cell function. The mechanism of insulin secretion studied with the aid of lanthanum

The Biochemical Journal
P R FlattB Hellman

Abstract

La3+ was used to study the involvement of Ca2+ in insulin secretion in beta-cell-rich pancreatic islets micro-dissected from non-inbred ob/ob mice. Ultrastructural studies revealed that the localization of La3+ was entirely restricted to the exterior of the cells. Consistent with a membrane action, exposure to La3+ failed to affect glucose oxidation and either the sucrose space or the general ultrastructure of the islets. In contrast, La3+ had marked effects on insulin release and 45Ca fluxes. Exposure to La3+ resulted in pronounced inhibition of insulin release irrespective of the presence or absence of Ca2+, 3-isobutyl-1-methylxanthine or glucose. Perifusion experiments revealed that the inhibitory action was prompt, sustained and readily reversible. Removal of La3+ was associated with a subsequent prolonged stimulatory phase of insulin release even in medium deficient in Ca2+. This action could not be attributed to an increase in cyclic AMP, but was potentiated by 3-isobutyl-1-methylxanthine and abolished by L-adrenaline. La3+ displaced 45Ca from superficially located binding sites and inhibited the uptake and efflux of 45Ca. The stimulatory and inhibitory actions of glucose on 45Ca efflux were also abolished in the presence...Continue Reading

Citations

Dec 1, 1988·Biological Trace Element Research·T DasG Talukder
Feb 1, 1982·Acta Physiologica Scandinavica·T AnderssonB Hellman
Sep 5, 2019·FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology·Alicia J KowaltowskiOrian S Shirihai
Jul 1, 1995·Journal of Inorganic Biochemistry·D Bingham, M Dobrota

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