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- Title
Plasma alloisoleucine: Analytical method and clearance in ketoacid-supplemented normals.
- Authors
Ponto, Kim H.; Anderson, Pamela A.; Kies, Constance V.
- Abstract
Chromatographic separation of alloisoleucine (ALE) was achieved using a Beckman 6300 Amino Acid Analyzer equipped with a 20 cm lithium High Performance column and Li-A buffer. Twenty microliter samples were injected and the initial column temperature was 57°C. After 1.0 minute, the temperature was increased at a rate of 0.75°C/min to 70°C. Flow rate was maintained at 22 ml/hr. ALE eluted at 46 minutes. Accuracy of the method was 97.2% with spike recovery studies. Repeated analyses (N = 9) of a plasma sample containing ALE gave a SD of 0.04 and 1.37% RSD. Linearity using standard solutions of 1.25 to 100 µmol/100 ml was confirmed by a correlation coefficient of r = 0.999. Limit of quantitation was estimated at 0.2 µmol/100 ml. This method was used to determine the half-life of ALE in plasma of healthy humans fed ketoanalogue-supplemented diets on the first day and after 28 days of consumption. Plasma samples were taken at 0, 0.5, 1.0, 1.5, 2, 3, 4, 6, 8, 10, 12 and 24 hours post-dose of either 6.2 ± 0.25 g or 9.3 ± 0.55 g (meal dose) of a ketoacid mixture (KAM) containing 10.9% (R,S) α-keto-β-methylvalerate. Plasma ALE peaked at two hours post-dose with mean (±SEM) values of 3.4 ± 0.1 and 5.1 ± 0.2 µmol/100 ml for the low and high dose, respectively, on Day 1. Subjects then consumed three meal doses daily until Day 29. Plasma ALE accumulated with time so that fasting levels on Day 29 were 5.2 ± 0.4 and 6.22 ± 0.4 µmol/100 ml. Mean (±SEM) peak values on Day 29 were 7.7 ± 0.4 and 9.66 ± 0.5 µmol/100 ml. Estimates of half-life were in the range of 7 to 12 hours.
- Subjects
AMINO acid analysis; KETONIC acids; CHROMATOGRAPHIC analysis; TEMPERATURE; DIET
- Publication
Kidney International Supplement, 1989, Issue 27, p177
- ISSN
0098-6577
- Publication type
Article
- DOI
10.1111/1523-1755.ep17656674