Pancreatic Function, Type 2 Diabetes, and Metabolism in Aging
Figure 1
The processes of GSIS. (1) Glucose is transported into the β cells through the translocation of the glucose transporters, especially GLUT2; (2) generation of ATP through the oxidation of glucose; (3) elevation the ratio of ATP/ADP induces closure of cell-surface ATP-sensitive K+ (KATP) channels, leading to cell membrane depolarization; (4) extracellular Ca2+ influx into the β cell; (5) a rise in cytosolic Ca2+ triggers the exocytosis of insulin granules. KATP: ATP-sensitive K+ channels, GLUT2: glucose transporter 2, GCK: phosphorylation by glucokinase, GPDH: glycerophosphate dehydrogenase, TCA cycle: tricarboxylic acid cycle, NADH: reduced form of Nicotinamide adenine dinucleotide, FADH2: reduced forms of flavin adenine dinucleotide, KG: alpha-ketoglutarate, ADP: adenosine diphosphate, ATP: Adenosine-5′-triphosphate.
