Figure 1

Figure 1: Pancreatic β-cell glucose-stimulated insulin secretion.  Glucose enters the cell through the glucose transporter 2 (GLUT2 transporter) and is metabolized to produce ATP, which increases the cytosolic ATP/ADP ratio.  This closes the K_ATP channel leading to membrane depolarization and activation of the voltage-dependent Ca²⁺ channel leading to an increase in cytosolic Ca²⁺ concentrations and activation of Ca²⁺-dependent mechanisms controlling insulin secretion.  In addition to the K_ATP-channel dependent pathway, there is also a K_ATP independent pathway.  This pathway involves modulation of insulin secretion by some metabolite of glucose metabolism that does not involve the K_ATP channel.