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posted 24. October 2004 13:37
Journal of Circadian Rhythms. September 3 2004.
Daily rhythms in plasma levels of homocysteine
Lena Lavie, and Peretz Lavie
Corresponding author.
Lena Lavie: lenal@tx.technion.ac.il; Peretz Lavie: plavie@tx.technion.ac.il
Received April 24, 2004; Accepted September 3, 2004.
Copyright © 2004 Lavie and Lavie; licensee BioMed Central Ltd.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
J Circadian Rhythms. 2004; 2: 5.
doi: 10.1186/1740-3391-2-5. Published online 2004 September 3.
Abstract
Background
There is accumulated evidence that plasma concentration of the sulfur-containing amino-acid homocysteine (Hcy) is a prognostic marker for cardiovascular morbidity and mortality. Both fasting levels of Hcy and post methionine loading levels are used as prognostic markers. The aim of the present study was to investigate the existence of a daily rhythm in plasma Hcy under strictly controlled nutritional and sleep-wake conditions. We also investigated if the time during which methionine loading is performed, i.e., morning or evening, had a different effect on the resultant plasma Hcy concentration.
Methods
Six healthy men aged 23–26 years participated in 4 experiments. In the first and second experiments, the daily rhythm in Hcy as well as in other amino acids was investigated under a normal or an inverse sleep-wake cycle. In the third and fourth, Hcy concentrations were investigated after a morning and evening methionine loading. To standardize food consumption in the first two experiments, subjects received every 3 hours 150 ml of specially designed low-protein liquid food (Ensure® formula).
Results
In both the first and second experiments there was a significant daily rhythm in Hcy concentrations with a mid-day nadir and a nocturnal peak. Strikingly different 24-h patterns were observed in methionine, leucine, isoleucine and tyrosine. In all, the 24-h curves revealed a strong influence of both the sleep-wake cycle and the feeding schedule. Methionine loading resulted in increased plasma Hcy levels during both morning and evening experiments, which were not significantly different from each other.
Conclusions
There is a daily rhythm in plasma concentration of the amino acid Hcy, and this rhythm is independent of sleep-wake and food consumption. In view of the fact that increased Hcy concentrations may be associated with increased cardiovascular risks, these findings may have clinical implications for the health of rotating shift workers.
See Full Text at Journal of Circadian Rhythms
[ 03. December 2004, 21:00: Message edited by: ISCID News Editor ]
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