The fractional synthesis rates of plasma proteins as determined using deuterated water are sensitive to dietary intake of lysine in rats
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Traditionally, the effect of dietary lysine upon health is determined through the concentrations of plasma proteins, but sometimes they are not responsive to lysine intake. We hypothesized that the fractional synthesis rates (FSRs) of plasma proteins may be more sensitive to dietary intake of lysine than protein concentrations in plasma. Seventy-two male Sprague–Dawley rats were divided randomly into three groups based on their diets provided for 18 weeks: low lysine (LG), normal lysine (NG) and high lysine (HG). Rats underwent labeling with deuterated water, a more reliable tracer than amino-acid tracers. The FSRs of albumin and immunoglobulin (Ig) G in plasma increased with increasing dietary intake of lysine. However, the albumin concentration in plasma in rats in the LG did not decrease significantly compared with that in the NG, and a similar result was shown for the IgG concentration between the NG and HG. These results suggested that the FSRs of albumin and IgG in plasma were more sensitive to dietary intake of lysine than their concentrations, and could be useful as sensitive indicators of the effect of dietary lysine upon health.
KeywordsLysine Albumin Immunoglobulin G Concentration Fractional synthesis rate Deuterated water
This study was funded by the National Natural Science Foundation of China (81472963). The authors are very grateful to Professor Xiaoguang Yang (National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention) for his invaluable suggestions on study design, and to Dr. Juan Liu (Analysis Center of Yangzhou University) for her skilled technical assistance.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This study was approved by the Animal Care and Use Committees of Yangzhou University. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
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