The stimulus-secretion coupling of amino acid-induced insulin release metabolic interaction L-asparagine and L-leucine in pancreatic islets |
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Authors: | W.J. Malaisse F. Malaisse-Lagae A. Sener |
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Affiliation: | Laboratory of Experimental Medicine, Brussels University, B-1000 BrusselsBelgium |
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Abstract: | 1. Because L-asparagine augments insulin release evoked by L-leucine, the metabolism of these two amino acids was investigated in rat pancreatic islets. 2. L-Leucine inhibited the uptake and deamidation of L-asparagine, but failed to exert any obvious primary effect upon the further catabolism of aspartate derived from exogenous asparagine. 3. L-Asparagine augmented the oxidation of L-leucine, and effect possibly attributable to activaion of 2-ketoisocaproate dehydrogenase. 4. The association of L-asparagine and L-leucine exerted a sparing action on the utilization of endogenous amino acids, so that the integrated rate of nutrients oxidation was virtually identical in the sole presence of L-leucine and simultaneous presence of L-asparagine and L-leucine, respectively. 5. It is proposed that the enhancing action of L-asparagine upon insulin release evoked by L-leucine is attributable to an increased generation rate of cytosolic NADPH rather than any increase in nutrients oxidation. |
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Keywords: | Asparagine Leucine Insulin release Amino acid Stimulus-secretion coupling (Pancreatic islet) |
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