Submitted on February 10, 2009
Revised on April 24, 2009
Accepted on April 24, 2009
Dynamics of glutathione and ophthalmate traced
with 2H-enriched body water in rats and humans
Rajan S. Kombu1, Guofang Zhang1, Rime Abbas1, John J. Mieyal1, Vernon E. Anderson2, Joanne K. Kelleher PhD3, Juan R. Sanabria1, and Henri Brunengraber4*
1 Case Western Reserve University-School of Medicine
2 CWRU
3 M.I.T.
4 Case Western Reserve University
* To whom correspondence should be addressed. E-mail: hxb8{at}case.edu.
We developed a LC-MS/MS assay of the 2H-labeling of free and bound glutathione (GSH and GSSR, which includes glutathione disulfide) and ophthalmate (an index of GSH depletion) labeled from 2H-enriched body water. In rats whose body water was 2.5% 2H-enriched for up to 31 days, GSH labeling follows a complex pattern because of different rates of labeling of its constitutive aminoacids. In rats infused with [13C2, 15N-glycine]glutathione, the rate of appearance of plasma GSH was 2.1 µmol•min-1•kg-1, and the half-life of plasma GSH/GSSR was 6-8 min. In healthy humans whose body fluids were 0.5% 2H-enriched, the 2H-labeling of GSH/GSSR and ophthalmate can be precisely measured after 4 hr, with GSH being more rapidly labeled than GSSR. Since plasma GSH/GSSR derives mostly from liver, this technique opens the way to (i) noninvasive probing of the labeling pattern and redox status of the liver GSH system in humans, and (ii) assessing the usefulness of ophthalmate as an index of GSH depletion.
