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Nutritional efficiency of alpha-ketoisocaproate relative to leucine, assessed isotopically

Authors :
C. W. Kang
M. Walser
Source :
American Journal of Physiology-Endocrinology and Metabolism. 249:E355-E359
Publication Year :
1985
Publisher :
American Physiological Society, 1985.

Abstract

The efficiency of alpha-ketoisocaproate as a dietary substitute for leucine was assessed in rats by two techniques: first, the minimal dose of alpha-ketoisocaproate required, as a supplement to a leucine-free diet, to achieve a growth rate as great as animals receiving leucine was found to be between 2.2 and 4.4 times larger. Therefore the nutritional efficiency of alpha-ketoisocaproate lies between 0.23 and 0.46. Second, alpha-[1-14C]-ketoisocaproate and [3H]leucine were administered orally and the ratio of 14C/3H incorporated into the leucine of whole-body protein and fibrin was measured. This ratio, divided by the ratio 14C/3H injected, was the same in fibrin as in whole-body protein and averaged 0.39. Thus both techniques yield the same value, within the error of measurement, for the relative nutritional efficiency of alpha-ketoisocaproate. We also found that alpha-ketoisocaproate feeding at varying dosage did not alter this ratio in whole-body protein (measured in rats fasted overnight), suggesting that neither wide variations in growth rate nor exposure for 10 days to alpha-ketoisocaproate (in a diet of constant protein content) alters the relative rates of utilization (or oxidation) of alpha-ketoisocaproate vs. leucine.

Details

ISSN :
15221555 and 01931849
Volume :
249
Database :
OpenAIRE
Journal :
American Journal of Physiology-Endocrinology and Metabolism
Accession number :
edsair.doi.dedup.....8025c8765c7967bea003a59842d4242e
Full Text :
https://doi.org/10.1152/ajpendo.1985.249.4.e355