In:
American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 286, No. 4 ( 2004-04), p. E665-E672
Abstract:
A method is introduced for quantitating protein synthetic rates in humans by use of 2 H 2 O. Its validity was tested in subjects with end-stage renal disease. Six clinically stable subjects, hemodialyzed three times weekly, ingested 2 H 2 O to a body water 2 H enrichment of ∼0.4%. On dialysis, body water enrichment declined to ∼0.1%. Enrichment of the α-hydrogen of plasma free alanine was also ∼0.4% before and ∼0.1% after dialysis. β-Hydrogen enrichment was ∼80-100% of α-hydrogen enrichment. 2 H 2 O was ingested to replace 2 H 2 O removed after each dialysis for 15-51 days, returning enrichment to ∼0.4%. Enrichment of alanine from plasma albumin gradually increased, with again ∼80-100% as much 2 H in β- as in α-hydrogens. With continued dialyses, without 2 H 2 O replacement, alanine from albumin enrichment gradually declined, whereas free alanine and water enrichments were negligible. The fractional albumin synthesis rate, calculated from the increase in enrichment in alanine from albumin, was 4.0 ± 0.5%/day, and from the decrease, 4.6 ± 0.2%/day. Thus body water enrichment in a subject given 2 H 2 O can be maintained constant long term. A rapid exchange, essentially complete, occurs between the hydrogens of alanine and body water. An integrated measure over a long period of albumin's synthetic rate can be estimated from both the rise in enrichment of alanine from the protein during 2 H 2 O ingestion and fall on 2 H 2 O withdrawal, while the subject's living routine is uninterrupted. Estimates are in subjects with renal disease, but the method should be applicable to estimates of protein synthetic rates in normal subjects and in other pathological states.
Type of Medium:
Online Resource
ISSN:
0193-1849
,
1522-1555
DOI:
10.1152/ajpendo.00271.2003
Language:
English
Publisher:
American Physiological Society
Publication Date:
2004
detail.hit.zdb_id:
1477331-4
SSG:
12
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