title: Opposite associations of plasma homoarginine and ornithine with arginine in healthy children and adolescents.
abstract: Homoarginine, a non-proteinogenic amino acid, is formed when lysine replaces ornithine in reactions catalyzed by hepatic urea cycle enzymes or lysine substitutes for glycine as a substrate of renal arginine:glycine amidinotransferase. Decreased circulating homoarginine and elevated ornithine, a downstream product of arginase, predict adverse cardiovascular outcome. Our aim was to investigate correlates of plasma homoarginine and ornithine and their relations with carotid vascular structure in 40 healthy children and adolescents aged 3-18 years without coexistent diseases or subclinical carotid atherosclerosis. Homoarginine, ornithine, arginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) were measured by liquid chromatography-tandem mass spectrometry with stable isotope-labeled internal standards. Intima-media thickness (IMT) and extra-medial thickness (EMT) of common carotid arteries were estimated by B-mode ultrasound. Homoarginine correlated with arginine (r = 0.43, p = 0.005), age (r = 0.42, p = 0.007) and, weakly, with an increased arginine-to-ornithine ratio, a putative measure of lower arginase activity (r = 0.31, p = 0.048). Ornithine correlated inversely with arginine (r = -0.64, p < 0.001). IMT, EMT or their sum were unrelated to any of the biochemical parameters (p > 0.12). Thus, opposite associations of plasma homoarginine and ornithine with arginine may partially result from possible involvement of arginase, an enzyme controlling homoarginine degradation and ornithine synthesis from arginine. Age-dependency of homoarginine levels can reflect developmental changes in homoarginine metabolism. However, neither homoarginine nor ornithine appears to be associated with carotid vascular structure in healthy children and adolescents.
authors.affiliation: Almed-Elektra Medical Center, 41-710 Ruda Śląska, Poland. surdacki.andreas@gmx.net.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Jaźwińska-Kozuba
authors.forename: Jens
authors.initials: J
authors.lastname: Martens-Lobenhoffer
authors.forename: Olga
authors.initials: O
authors.lastname: Kruszelnicka
authors.forename: Jarosław
authors.initials: J
authors.lastname: Rycaj
authors.forename: Bernadeta
authors.initials: B
authors.lastname: Chyrchel
authors.forename: Andrzej
authors.initials: A
authors.lastname: Surdacki
authors.forename: Stefanie M
authors.initials: SM
authors.lastname: Bode-Böger
mesh_terms: D000293:Adolescent; D001120:Arginine / Q000031:analogs & derivatives / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006709:Homoarginine / Q000097:blood*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008297:Male; D009952:Ornithine / Q000097:blood*; D013223:Statistics as Topic; D017539:Tunica Intima / Q000378:metabolism / Q000473:pathology
chemical_list: C487735:dimethylarginine; D006709:Homoarginine; D001120:Arginine; D009952:Ornithine; D008239:Lysine