Determination of extracellular and intracellular enrichments of [1-(13)C]-alpha-ketoisovalerate using enzymatically converted [1-(13)C]-valine standardization curves and gas chromatography-mass spectrometry. |
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| Authors: | W Kulik C Jakobs K de Meer |
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| Institution: | Department of Clinical Chemistry, University Hospital Vrije Universiteit, Amsterdam, The Netherlands. w.kulik@azvu.nl |
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| Abstract: | We report a validated method for the determination of extra- and intracellular 1-(13)C]-alpha-ketoisovalerate (1-(13)C]-KIV) enrichments by gas chromatography-mass spectrometry. Standardization curves were prepared by enzymatic oxidation of 1-(13)C]-valine enriched standards of known composition. Slopes of 1-(13)C]-valine standardization curves (mean+/-SD: 0.99+/-0.02, n=5) and 1-(13)C]-KIV standardization curves (mean+/-SD: 0.98+/-0.01, n=7) were not significantly different. The method was applied for the determination of 1-(13)C]-KIV enrichments in plasma and tissues during 1-(13)C]-valine infusion in a piglet. 1-(13)C]-KIV enrichment could be determined+/-0.1 MPE (C.V. 1%), and extracellular 1-(13)C]-KIV enrichment was a reliable estimate of intracellular (skeletal muscle, bone growth plate) 1-(13)C]-KIV enrichment. |
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