title: Direct detection and evaluation of conversion of D-methionine into L-methionine in rats by stable isotope methodology.
abstract: The stereoselective kinetics of methionine enantiomers in rats was investigated to evaluate the fraction that converted from d-methionine to the L-enantiomer using a stable isotope methodology. After bolus i.v. administration of D- or L-[(2)H(3)]methionine, their plasma concentrations and that of endogenous L-methionine were determined by a stereoselective GC-MS method. L-[(2)H(3)]Methionine appeared rapidly after administration of D-[(2)H(3)]methionine, whereas D-[(2)H(3)]methionine was not detected after administration of L-[(2)H(3)]methionine. The fraction of conversion of D-[(2)H(3)]methionine into L-[(2)H(3)]methionine was estimated using the area under the plasma concentration vs. time curve of L-[(2)H(3)]methionine on D-[(2)H(3)]methionine administration and total clearance of L-[(2)H(3)]methionine on L-[(2)H(3)]methionine administration, and that fraction was >90%. This result demonstrates that almost all i.v. administered D-methionine is converted into the L-enantiomer in vivo.
authors.affiliation: Department of Pathophysiology, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan. hasegawa@ps.toyaku.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Kenji
authors.initials: K
authors.lastname: Akahane
authors.forename: Takao
authors.initials: T
authors.lastname: Hashimoto
mesh_terms: D000818:Animals; D019540:Area Under Curve; D008401:Gas Chromatography-Mass Spectrometry; D007553:Isotope Labeling / Q000379:methods; D008715:Methionine / Q000097:blood / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D013237:Stereoisomerism; D014316:Tritium
chemical_list: D014316:Tritium; D008715:Methionine