Article révisé par les pairs
Résumé : 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, an effect possibly attributable to activation 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.