Glucose controls glucagon secretion with minor changes in alpha cell [Ca2+]c whereas sulfonylureas control glucagon secretion by increasing alpha cell [Ca2+]c and via somatostatin

Abstract

BACKGROUND AND AIMS: The mechanisms by which glucose (G) and KATP channels control glucagon release are poorly understood. A rise in [Ca2+]c is considered as a signal triggering glucagon secretion. However, the effects of glucose and KATP channels on α-cell [Ca2+]c are hotly debated. In the present study, we tested the effects of glucose and KATP channel blockers (sulfonylureas) on α-cell [Ca2+]c using mice expressing the Ca2+indicator, GCAMP6f, specifically in α-cells, and we studied the correlation between α-cell [Ca2+]c and glucagon secretion. We also investigated the paracrine influence of somatostatin (SST) using Sst-/- mice. [...