title: Improvement of sympathetic response to exercise by oral administration of ascorbic acid in patients after myocardial infarction.
abstract: BACKGROUND
  Recent studies indicated that excessive oxidative stress in an animal heart failure model injures both the sympathetic nerve endings and receptors, resulting in disturbance of norepinephrine release and sensitivity to norepinephrine. However, it has not been clarified whether this phenomenon is expressed clinically in patients with heart disease. Therefore, we examined the efficacy of ascorbic acid administration as an antioxidant vitamin in relation to the heart rate and norepinephrine response to exercise in patients after myocardial infarction.
  
  
  METHODS
  In this randomized crossover trial, 21 male patients who had had myocardial infarction underwent symptom-limited ergometer cardiopulmonary exercise testing twice, that is, without and with ascorbic acid (2 g) administration. Plasma norepinephrine concentrations were assessed at rest and at peak exercise, and heart rate responsiveness to the norepinephrine increment from rest to peak exercise (DeltaHR/logDeltaNE) was calculated.
  
  
  RESULTS
  In the exercise test after ascorbic acid administration, peak oxygen consumption (VO(2)) improved over baseline. Ascorbic acid administration significantly increased the change in heart rate and norepinephrine from rest to peak exercise and DeltaHR/logDeltaNE. The increment in heart rate was significantly correlated with peak VO(2) in each test.
  
  
  CONCLUSIONS
  Ascorbic acid intake before exercise improved exercise capacity through enhancement of the heart rate and norepinephrine response to exercise in patients after myocardial infarction. These findings suggest that ascorbic acid intake improves sympathetic dysfunction resulting from injury by excessive oxidative stress after myocardial infarction.
authors.affiliation: The First Department of Internal Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan. s3088@nms.ac.jp
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Kato
authors.forename: Nagaharu
authors.initials: N
authors.lastname: Fukuma
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kimura-Kato
authors.forename: Noriko
authors.initials: N
authors.lastname: Aisu
authors.forename: Takaya
authors.initials: T
authors.lastname: Tuchida
authors.forename: Kousuke
authors.initials: K
authors.lastname: Mabuchi
authors.forename: Teruo
authors.initials: T
authors.lastname: Takano
mesh_terms: D000368:Aged; D001205:Ascorbic Acid / Q000097:blood / Q000627:therapeutic use*; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology / Q000628:therapy*; D009638:Norepinephrine / Q000097:blood / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D012146:Rest; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology
chemical_list: D001205:Ascorbic Acid; D009638:Norepinephrine