Time Dependent Potentiation of Insulin secretion
Glucose causes time dependent potentiation(TDP) of insulin secretion; that is exposure of islets beta cells to high glucose enhances insulin release in response to the stimulus applied later. Metabolizable amino acids and the glycolytic intermediates, glyceraldehyde show similar enhancement of insulin secretion. Conversely, non-metabolizable secretagogues, such as sulfanylurea(SU) and high K+, do not prime the beta cells in this TDP manner. In contrast merabolic inhibition abolishes TDP by glucose and the amino acids. Therefore metabolic stimulus, the mitochondrial intermediates in the case of amino acids, is required for TDP. Pharmacological activation of protein kinase C (pkC) by phorbolester also timedependently potentiates insulin secretion.
The beta cell priming by glucose through TDP manner occurs in a KATP channel independent manner. TDP also occurs under stringent Ca2+ free conditions.
by -Souti Das
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