Comprehensive analysis of the L-arginine/L-homoarginine/nitric oxide pathway in preterm neonates: potential roles for homoarginine and asymmetric dimethylarginine in foetal growth.
L-Arginine (Arg) and L-homoarginine (hArg) are precursors of nitric oxide (NO), a signalling molecule with multiple important roles in human organism. In the circulation of adults, high concentrations of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) and low concentrations of hArg emerged as cardiovascular risk factors. Yet, the importance of the Arg/hArg/NO pathway, especially of hArg and ADMA, in preterm neonates is little understood. We comprehensively investigated the Arg/hArg/NO pathway in 106 healthy preterm infants (51 boys, 55 girls) aged between 23 + 6 and 36 + 1 gestational weeks. Babies were divided into two groups: group I consisted of 31 babies with a gestational age of 23 + 6 - 29 + 6 weeks; group II comprised 75 children with a gestational age of 30 + 0 - 36 + 1 weeks. Plasma and urine concentrations of ADMA, SDMA, hArg, Arg, dimethylamine (DMA) which is the major urinary ADMA metabolite, as well as of nitrite and nitrate, the major NO metabolites, were determined by GC-MS and GC-MS/MS methods. ADMA and hArg plasma levels, but not the hArg/ADMA molar ratio, were significantly higher in group II than in group I: 895 ± 166 nM vs. 774 ± 164 nM (P = 0.001) for ADMA and 0.56 ± 0.04 µM vs. 0.48 ± 0.08 µM (P = 0.010) for hArg. There was no statistical difference between the groups with regard to urinary ADMA (12.2 ± 4.6 vs 12.8 ± 3.6 µmol/mmol creatinine; P = 0.61) and urinary SDMA. Urinary hArg, ADMA, SDMA correlated tightly with each other. Urinary excretion of DMA was slightly higher in group I compared to group II: 282 ± 44 vs. 247 ± 35 µmol/mmol creatinine (P = 0.004). The DMA/ADMA molar ratio in urine was tendentiously higher in neonates of group I compared to group II: 27 ± 13 vs. 20 ± 5 (P = 0.065). There were no differences between the groups with respect to Arg in plasma and to nitrite and nitrate in plasma and urine. In preterm neonates, ADMA and hArg biosynthesis increases with gestational age without remarkable changes in the hArg/ADMA ratio or NO biosynthesis. Our study suggests that ADMA and hArg are involved in foetal growth.
Department of Pediatrics, Hannover Medical School, Hannover, Germany.
Anna
A
Buck
Centre of Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.
Arslan Arinc
AA
Kayacelebi
Department of Pediatrics, Hannover Medical School, Hannover, Germany.|Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany.
Kristine
K
Chobanyan-Jürgens
Clinic for Pediatric Kidney-, Liver- and Metabolic Diseases, Hannover Medical School Hannover, Hannover, Germany.
Sabine
S
Illsinger
Department of Paediatric Pulmonology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.
Bettina
B
Bohnhorst
Centre of Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.
Bibiana
B
Beckmann
Centre of Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.
Erik
E
Hanff
Clinic for Pediatric Kidney-, Liver- and Metabolic Diseases, Hannover Medical School Hannover, Hannover, Germany.
Anibh M
AM
Das
Centre of Pharmacology and Toxicology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany. tsikas.dimitros@mh-hannover.de.
Dimitrios
D
Tsikas
Department of Neuropaediatrics, University Children's Hospital, Ruhr University, Bochum, Germany.
Thomas
T
Lücke
D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000502:physiology; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006709:Homoarginine / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D053858:Metabolic Networks and Pathways; D009569:Nitric Oxide / Q000378:metabolism*
C487735:dimethylarginine; D006709:Homoarginine; D009569:Nitric Oxide; D001120:Arginine
ADMA; Growth; Homoarginine; Nitric oxide (NO); Nitric oxide synthase (NOS); Preterm neonates