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Nutrient insulin secretagogues decrease 45Ca2+ efflux from islet cells by a mechanism other than the inhibition of the Na+-Ca2+ countertransport.

J C Henquin·R de Miguel·M G Garrino·M Hermans·M Nenquin
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Abstract

The mechanism whereby nutrient insulin secretagogues decrease 45Ca2+ efflux from islet cells is controversial. It was studied with mouse islets perifused with Ca2+-free solutions. In the presence of Na+, glucose and ketoisocaproate inhibited 45Ca2+ efflux by about 50%. Substitution of choline+ salts for Na+ salts decreased the efflux rate by 45%, but did not prevent glucose from decreasing it further. Ketoisocaproate also inhibited 45Ca2+ efflux, but less markedly than in an Na+ medium. Omission of Na+ decreased the efflux rate even when it was already lowered by glucose or ketoisocaproate. It is thus clear that nutrient insulin secretagogues decrease 45Ca2+ efflux from islet cells by a mechanism other than the inhibition of the Na+-Ca2+ countertransport, possibly by increasing sequestration of the ion in cellular organelles.

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AnimalsBiological Transport, ActiveCalciumCholineEgtazic AcidFemaleGlucoseInsulinInsulin SecretionIslets of LangerhansKeto AcidsMagnesiumMagnesium ChlorideMiceSodiumJournal ArticleResearch Support, Non-U.S. Gov't

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J C Henquin, R de Miguel, M G Garrino, M Hermans, M Nenquin. 1985-07-22. Nutrient insulin secretagogues decrease 45Ca2+ efflux from islet cells by a mechanism other than the inhibition of the Na+-Ca2+ countertransport.. https://doi.org/10.1016/0014-5793(85)81237-0

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