| Autor: |
Cuskelly GJ; Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611-0307, USA., Stacpoole PW, Williamson J, Baumgartner TG, Gregory JF 3rd |
| Jazyk: |
angličtina |
| Zdroj: |
American journal of physiology. Endocrinology and metabolism [Am J Physiol Endocrinol Metab] 2001 Dec; Vol. 281 (6), pp. E1182-90. |
| DOI: |
10.1152/ajpendo.2001.281.6.E1182 |
| Abstrakt: |
Folate and vitamin B(6) act in generating methyl groups for homocysteine remethylation, but the kinetic effects of folate or vitamin B(6) deficiency are not known. We used an intravenous primed, constant infusion of stable isotope-labeled serine, methionine, and leucine to investigate one-carbon metabolism in healthy control (n = 5), folate-deficient (n = 4), and vitamin B(6)-deficient (n = 5) human subjects. The plasma homocysteine concentration in folate-deficient subjects [15.9 +/- 2.1 (SD) micromol/l] was approximately two times that of control (7.4 +/- 1.7 micromol/l) and vitamin B(6)-deficient (7.7 +/- 2.1 micromol/l) subjects. The rate of methionine synthesis by homocysteine remethylation was depressed (P = 0.027) in folate deficiency but not in vitamin B(6) deficiency. For all subjects, the homocysteine remethylation rate was not significantly associated with plasma homocysteine concentration (r = -0.44, P = 0.12). The fractional synthesis rate of homocysteine from methionine was positively correlated with plasma homocysteine concentration (r = 0.60, P = 0.031), and a model incorporating both homocysteine remethylation and synthesis rates closely predicted plasma homocysteine levels (r = 0.85, P = 0.0015). Rates of homocysteine remethylation and serine synthesis were inversely correlated (r = -0.89, P < 0.001). These studies demonstrate distinctly different metabolic consequences of vitamin B(6) and folate deficiencies. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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