title: Sympathetic nervous response relative to the adenosine triphosphate supply-demand imbalance during exercise is augmented in patients with heart failure.
abstract: OBJECTIVE
  Increase in plasma hypoxanthine (HX) (purine nucleotide degradation product from working muscle) reflects insufficiency of adenosine triphosphate (ATP) supply during exercise, and the exercise-induced increase in plasma norepinephrine (NE) can be an index of sympathetic nerve activity. The aim of this study was to investigate the relationship between plasma NE and plasma HX during exercise in patients with heart failure (HF) according to its severity.
  
  
  METHODS
  Blood lactate, plasma HX, and plasma NE were measured at rest and after symptom-limited cardiopulmonary exercise test in 54 patients with HF (New York Heart Association [NYHA] classes I:18, II:20, III:16) and 19 normal subjects.
  
  
  RESULTS
  Peak work rate and peak oxygen uptake decreased as the NYHA functional class increased. Blood lactate and plasma HX levels at rest were comparable, but peak blood lactate (normal, NYHA I, II, III: 6.4+/-0.3, 5.6+/-0.4, 5.3+/-0.3, 3.5+/-0.2 mmol/L) and peak plasma HX (3.6+/-0.4, 3.0+/-0.5, 2.4+/-0.3, 1.4+/-0.1 micromol/L) were progressively smaller as HF worsened. Resting plasma NE (137+/-15, 180+/-29, 201+/-21, 318+/-55 pg/mL) was significantly higher in NYHA class III HF, but peak plasma NE (2,235+/-356, 2,021+/-326, 2,188+/-292, 2,210+/-316 pg/mL) was not different among groups. The ratio of the exercise increments in plasma NE to the increments in plasma HX during exercise (deltaplasma NE/deltaplasma HX: 666+/-96, 1,083+/-229, 1,252+/-222, 2,260+/-351) increased according to the severity of HF.
  
  
  CONCLUSIONS
  These data suggest that plasma levels of HX after maximal exercise are smaller as HF worsened, and sympathetic responsiveness to the imbalance of ATP supply-demand during exercise is augmented according to the severity of HF.
authors.affiliation: First Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan. kinugawa@grape.med.tottori-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kinugawa
authors.forename: K
authors.initials: K
authors.lastname: Ogino
authors.forename: N
authors.initials: N
authors.lastname: Noguchi
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: H
authors.initials: H
authors.lastname: Miyakoda
authors.forename: I
authors.initials: I
authors.lastname: Hisatome
authors.forename: C
authors.initials: C
authors.lastname: Shigemasa
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D015308:Anaerobic Threshold; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D019271:Hypoxanthine / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption; D013564:Sympathetic Nervous System / Q000503:physiopathology*
chemical_list: D019271:Hypoxanthine; D019344:Lactic Acid; D000244:Adenosine Diphosphate; D009638:Norepinephrine