Tuesday, August 9, 2011

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Insulin secretion - local regulation


The diagram shows a beta cell of the islet of pancreas and will explain how local factors regulate secretion of insulin from it.
Glucose enters the cell via the GLUT-2 transporter. Inside the cell there is metabolism with the generation of ATP. This causes the ATP-sensitive K+ channel to close, as shown in A.
Closure of this channel leads to cell membrane depolarization. This in turn allows calcium ions to enter the cell via another calcium channel, shown in B. Increased intracellular calcium activates calcium dependent phospholipid protein kinase. This leads to exocytosis of insulin granules.

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