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

FEBS Letters

Hermans, M.¹  Henquin, J.C.¹  de Miguel, R.¹  Garrino, M.G.¹  Nenquin, M.¹ 

[1] Unité de Diabétologie et Nutrition, University of Louvain, Faculty of Medicine, UCL 54.74, B 1200 Brussels, Belgium

关键词: Pancreatic islet Glucose Ketoisocaproate Calcium efflux Sodium Sodium-calcium countertransport;   

DOI  :  10.1016/0014-5793(85)81237-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown