Validation of a method for measuring the short-term rate of urea synthesis after an amino acid load

Author:

Kay J. D. S.1,Seakins J. W. T.1,Geiseler D.1,Hjelm M.1

Affiliation:

1. The Department of Clinical Biochemistry, The Institute of Child Health, University of London, and the Hospitals for Sick Children, London

Abstract

1. The response of the plasma concentration of urea to the oral and intravenous administration of alanine was studied in healthy adult humans. 2. The instantaneous rate of urea synthesis was calculated by using a model-dependent procedure. The errors in this procedure were calculated and it was shown that analytical precision and sampling frequency, and the estimates of the distribution volume and elimination fluxes, were adequate to determine the synthesis parameters. 3. A direct test of the compartmental model was made by the intravenous injection of exogenous urea. The one-compartment model with first-order elimination gave a good fit to the experimental results at times greater than 8 min after the injection. 4. Both oral and intravenous loads of alanine had dose-dependent effects on the rate of urea synthesis. There was no evidence of a limit to the maximum possible rate of urea synthesis in these experiments and the values obtained were similar to published results for different stimuli and methods of measurement. 5. The rate of synthesis increased more rapidly after intravenous loads and subjective side-effects were less severe. The intravenous administration of alanine appears to be a suitable stimulus for urea synthesis.

Publisher

Portland Press Ltd.

Subject

General Medicine

Cited by 19 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Effect of protein restriction on15N transfer from dietary [15N]alanine and [15N]Spirulina platensisinto urea;American Journal of Physiology-Endocrinology and Metabolism;2001-08-01

2. Sulfate production depicts fed-state adaptation to protein restriction in humans;American Journal of Physiology-Endocrinology and Metabolism;2001-08-01

3. Use of sulfate production as a measure of short-term sulfur amino acid catabolism in humans;American Journal of Physiology-Endocrinology and Metabolism;2001-06-01

4. Tracer methods underestimate short-term variations in urea production in humans;American Journal of Physiology-Endocrinology and Metabolism;1998-03-01

5. Metabolic adaptation to protein restriction in insulin-dependent diabetes mellitus;American Journal of Physiology-Endocrinology and Metabolism;1997-01-01

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