title: Measurement of unlabeled and stable isotope-labeled homoarginine, arginine and their metabolites in biological samples by GC-MS and GC-MS/MS.
abstract: Circulating and excretory L-homoarginine (hArg) and asymmetric dimethylarginine (ADMA) are cardiovascular risk factors. L-Arginine (Arg) is the common precursor of hArg and ADMA. This protocol describes gas chromatography-mass spectrometry (GC-MS) and gas chromatography-mass spectrometry-mass spectrometry (GC-MS/MS) methods for the quantitative determination of hArg, Arg and ADMA in biological samples, including human plasma, urine and sputum. Aliquots (10 µL) of native urine, plasma or serum ultrafiltrate (cutoff, 10 kDa), and acetone-deproteinized sputum samples are evaporated to dryness. Then, amino acids are derivatized to their methyl ester N-pentafluoropropionyl derivatives. In parallel, trideuteromethyl ester N-pentafluoropropionyl derivatives of hArg, Arg and ADMA are de novo synthesized from the unlabelled amino acids and used as internal standards. Alternatively, commercially available stable isotope-labeled analogs of hArg, Arg and ADMA are used as internal standards, and they are added to the native biological samples. Quantification is performed by selected ion monitoring in GC-MS and selected reaction monitoring in GC-MS/MS. By these protocols, unlabelled and stable isotope-labeled hArg, Arg and their metabolites including ADMA and ornithine can be measured equally accurately and precisely by GC-MS and GC-MS/MS in several different biological fluids in experimental and clinical settings.
authors.affiliation: Bioanalytical Research Laboratory for NO, Oxidative Stress and Eicosanoids (BIOFORNOX20), Centre of Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany.
authors.forename: Arslan Arinc
authors.initials: AA
authors.lastname: Kayacelebi
authors.forename: Ann-Kathrin
authors.initials: AK
authors.lastname: Knöfel
authors.forename: Bibiana
authors.initials: B
authors.lastname: Beckmann
authors.forename: Erik
authors.initials: E
authors.lastname: Hanff
authors.forename: Gregor
authors.initials: G
authors.lastname: Warnecke
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Tsikas
mesh_terms: D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006709:Homoarginine / Q000097:blood* / Q000652:urine*; D006801:Humans; D007553:Isotope Labeling; D008297:Male; D012680:Sensitivity and Specificity; D013183:Sputum / Q000378:metabolism*
chemical_list: D006709:Homoarginine