title: Vitamin C restores the contractile response to dobutamine and improves myocardial efficiency in patients with heart failure after anterior myocardial infarction.
abstract: BACKGROUND
  Excessive oxidative stress is considered one of the mechanisms of a decrease in contractile force without concomitant reduction in oxygen cost in failing myocardium. We hypothesized that the antioxidant vitamin C may help reverse hyporesponsiveness to beta-adrenergic stimulation and improve myocardial efficiency in patients with heart failure (HF) after myocardial infarction (MI).
  
  
  RESULTS
  Nineteen patients with mild to moderate HF due to previous MI (mean left ventricular [LV] ejection fraction 39%) were instrumented with conductance and coronary sinus thermodilution catheters. Left ventricular contractility, expressed as E(es), the slope of end-systolic pressure-volume relationship, and mechanical efficiency, expressed as the ratio of LV stroke work (SW) to myocardial oxygen consumption (MVO2), were measured in response to the intravenous infusion of dobutamine (4 microg/kg per min) before (Dob) and during (Dob + Vit C) the infusion of vitamin C (2.0-g bolus injection and subsequent 50-mg/min infusion through the jugular vein) (vitamin C group, n = 10). The infusion of vitamin C augmented the E(es) response to dobutamine by 20% +/- 8% (Dob 2.1 +/- 0.3, Dob + Vit C 2.5 +/- 0.4 mm Hg/mL, P < .01) and the SW/MVO2 response by 21% +/- 5% (Dob 36% +/- 3%, Dob + Vit C 43% +/- 4%, P < .01). In the control group (n = 9), E(es) and SW/MVO2 were measured in response to dobutamine before (Dob) and during (Dob + vehicle) the infusion of saline. No difference in E(es) or SW/MVO2 was observed between Dob and Dob + vehicle (E(es): Dob 2.1 +/- 0.2, Dob + vehicle 2.1 +/- 0.2 mm Hg/mL per square meter, P = nonsignificant) (SW/MVO2: Dob 35% +/- 4%, Dob + vehicle 33% +/- 4%, P = nonsignificant).
  
  
  CONCLUSIONS
  The administration of the antioxidant vitamin C enhances the contractile response to dobutamine and improves myocardial efficiency in patients with HF.
authors: Division of Cardiovascular and Respiratory Medicine, Kobe University Graduate School of Medicine, Kobe, Japan. shinke@med.kobe-u.ac.jp
authors: Toshiro
authors: T
authors: Shinke
authors: Junya
authors: J
authors: Shite
authors: Hideyuki
authors: H
authors: Takaoka
authors: Katsuya
authors: K
authors: Hata
authors: Nobutaka
authors: N
authors: Inoue
authors: Ryohei
authors: R
authors: Yoshikawa
authors: Hidenari
authors: H
authors: Matsumoto
authors: Hiroyuki
authors: H
authors: Masai
authors: Satoshi
authors: S
authors: Watanabe
authors: Tohru
authors: T
authors: Ozawa
authors: Hiromasa
authors: H
authors: Otake
authors: Daisuke
authors: D
authors: Matsumoto
authors: Ken-ichi
authors: K
authors: Hirata
authors: Mitsuhiro
authors: M
authors: Yokoyama
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000975:Antioxidants / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000494:pharmacology*; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004280:Dobutamine / Q000494:pharmacology*; D005260:Female; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D017382:Reactive Oxygen Species / Q000494:pharmacology; D013815:Thermodilution; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000975:Antioxidants; D002316:Cardiotonic Agents; D017382:Reactive Oxygen Species; D004280:Dobutamine; D001205:Ascorbic Acid