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Methionine and cysteine kinetics at different intakes of cystine in healthy adult men.
- Source :
-
The American journal of clinical nutrition [Am J Clin Nutr] 1994 Oct; Vol. 60 (4), pp. 525-33. - Publication Year :
- 1994
-
Abstract
- We investigated plasma methionine and cysteine kinetics in eight healthy adult men receiving for 6 d each of five L-amino acid diets supplying 13 mg methionine.kg-1.d-1 without cystine or 6.5 mg methionine.kg-1.d-1 plus 0, 5.2, 10.5, or 20.9 mg cystine.kg-1.d-1. On the morning of day 7, primed, constant intravenous infusions of L-[2H3-methyl, 1-13C]methionine and L-[3,3-2H]cysteine were given for 8 h (for the first 3 h subjects remained in a fasted state and for the next 5 h received small, equal meals at hourly intervals to achieve a fed state). Methionine and cysteine fluxes and rate of methionine oxidation were estimated from plasma methionine and cysteine labeling and 13C in expired air. Methionine oxidation declined (P < 0.05) with lowered methionine intake. Cysteine flux was similar across diets and dietary cystine did not affect tracer methionine oxidation. If there is a sparing effect of dietary cystine on the methionine requirement in adults, it probably takes place during the "first-pass" removal of these amino acids within the splanchnic region.
Details
- Language :
- English
- ISSN :
- 0002-9165
- Volume :
- 60
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The American journal of clinical nutrition
- Publication Type :
- Academic Journal
- Accession number :
- 8092087
- Full Text :
- https://doi.org/10.1093/ajcn/60.4.525