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The stimulus-secretion coupling of amino acid-induced insulin release. Metabolic response of pancreatic islets of L-glutamine and L-leucine.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 1982 Aug 10; Vol. 257 (15), pp. 8731-7. - Publication Year :
- 1982
-
Abstract
- L-Glutamine markedly enhances insulin release evoked by L-leucine in rat pancreatic islets. The metabolic situation found in the islets exposed to both L-glutamine and L-leucine was investigated. L-Leucine slightly decreased the rate of L-glutamine deamidation, inhibited the conversion of glutamate to 2-ketoglutarate by transamination, increased the oxidative deamination of L-glutamate, stimulated the recirculation of 2-ketoglutarate to glutamate and inhibited the further oxidative metabolism of 2-ketoglutarate. L-Glutamine slightly decreased the rate of L-leucine conversion to 2-ketoisocaproate, but inhibited more severely the conversion of 2-ketoisocaproate to acetoacetate and CO2. Several of these findings appeared attributable to activation of glutamate dehydrogenase by L-leucine. When allowance was made for the influence of exogenous amino acids on the oxidation of endogenous fatty acids, a close parallelism was found between the rate of generation of reducing equivalents or O2 uptake and the insulin secretory response to L-leucine and/or L-glutamine. These findings reinforce the view that the process of nutrient-stimulated insulin release coincides with and may be attributable to an increase in catabolic fluxes in the islet cells.
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 257
- Issue :
- 15
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 7047526