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Figure 1

Schematic model for glucose-dependent regulation of glucagon secretion in the mouse α-cell. Glucose is incorporated into the α-cell by the transporter SLC2A1. At low-glucose concentrations, the moderate activity of KATP channels situates the α-cell membrane potential in a range that allows the opening of voltage-dependent T- and N-type Ca2+ channels and voltage-dependent Na+ channels. Their activation triggers action potentials, Ca2+ influx and exocytosis of glucagon granules. The opening of A-type K+ channels is necessary for action potential repolarization. However, high-glucose concentrations elevate the intracellular ATP/ADP ratio, blocking KATP channels and depolarizing the membrane potential to a range where the inactivation of voltage-dependent channels takes place. This results in the inhibition of electrical activity, Ca2+ influx and glucagon secretion. The function of L-type channels predominates when cAMP levels are elevated. See text for further details.

This Article

  1. J Endocrinol vol. 199 no. 1 5-19