title: Alterations in whole-body arginine metabolism in chronic obstructive pulmonary disease.
abstract: Chronic obstructive pulmonary disease (COPD) is a condition characterized by systemic low-grade inflammation that could increase the production of nitric oxide (NO), of which arginine is the sole precursor. Arginine is derived from the breakdown of protein and through the conversion of citrulline to arginine (de novo arginine production).
  
  
  
  Our objective was to study whole-body arginine and citrulline and related metabolism in stable COPD patients.
  
  
  
  With the use of stable isotope methodology, we studied whole-body arginine and citrulline rates of appearance, de novo arginine (citrulline-to-arginine flux) and NO (arginine-to-citrulline flux) production, protein synthesis and breakdown rates, and plasma amino acid concentrations in a heterogeneous group of patients with moderate-to-severe COPD [n = 23, mean ± SE age: 65 ± 2 y, forced expiratory volume in 1 s (FEV1): 40% ± 2% of predicted], and a group of healthy older adults (n = 19, mean ± SE age: 64 ± 2 y, FEV1: 95% ± 4% of predicted).
  
  
  
  Although plasma arginine and citrulline concentrations were comparable between COPD patients and controls, whole-body arginine (P = 0.015) and citrulline (P = 0.026) rates of appearance were higher in COPD patients and related to a 57% greater de novo arginine production (P < 0.0001). Despite a higher whole-body arginine clearance in COPD patients (P < 0.0001), we found no difference in NO production.
  
  
  
  In stable patients with moderate-to-severe COPD, endogenous arginine production is upregulated to support a higher arginine utilization that is unrelated to whole-body NO production. This trial was registered at clinicaltrials.gov as NCT01173354 and NCT01172314.
authors.affiliation: Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX; and Departments of Geriatrics and.
authors.forename: Renate
authors.identifier: 0000-0002-5874-9060
authors.initials: R
authors.lastname: Jonker
authors.affiliation: Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX; and Departments of Geriatrics and nep.deutz@ctral.org.
authors.forename: Nicolaas Ep
authors.identifier: 0000-0001-5845-6447
authors.initials: NE
authors.lastname: Deutz
authors.affiliation: Pulmonary and Critical Care Medicine, University of Arkansas for Medical Sciences, Little Rock, AR.
authors.forename: Marcia L
authors.initials: ML
authors.lastname: Erbland
authors.affiliation: Pulmonary and Critical Care Medicine, University of Arkansas for Medical Sciences, Little Rock, AR.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Anderson
authors.affiliation: Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX; and Departments of Geriatrics and.
authors.forename: Mariëlle Pkj
authors.identifier: 0000-0001-9884-2553
authors.initials: MP
authors.lastname: Engelen
mesh_terms: D000368:Aged; D000596:Amino Acids / Q000097:blood; D001120:Arginine / Q000097:blood / Q000378:metabolism*; D002956:Citrulline / Q000097:blood / Q000378:metabolism; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D000596:Amino Acids; D011506:Proteins; D002956:Citrulline; D009569:Nitric Oxide; D001120:Arginine
keywords: COPD; arginine; citrulline; nitric oxide; protein breakdown