title: Vitamin C augments the inotropic response to dobutamine in humans with normal left ventricular function.
abstract: BACKGROUND
  We studied the effect of an antioxidant, the intracoronary infusion of vitamin C, on basal and dobutamine-stimulated left ventricular (LV) contractility.
  
  
  RESULTS
  Nineteen patients with normal ventricular function participated in this study. A micromanometer-tipped catheter was inserted into the LV. In the experimental group (n=10), an infusion catheter was positioned in the left main coronary artery. LV peak +dP/dt (LV +dP/dt) was measured in response to the intravenous infusion of dobutamine before (Dob) and during (Dob+vit C) the intracoronary infusion of vitamin C. The intracoronary infusion of vitamin C had no effect on basal LV +dP/dt or any other hemodynamic parameter. The infusion of vitamin C augmented the LV +dP/dt response to dobutamine by 22+/-4% (Dob, 1680+/-76 mm Hg/s; Dob+vit C, 1814+/-97 mm Hg/s, P<0.01). In the control group (n=9), LV +dP/dt was measured in response to sequential infusions of dobutamine (Dob, Dob-2) given at the same time intervals as in the experimental group but without the intracoronary infusion of vitamin C. In contrast to the experimental group, no difference in LV +dP/dt was observed between the 2 infusions of dobutamine (Dob, 1706+/-131 mm Hg/s; Dob-2, 1709+/-138 mm Hg/s, P=NS).
  
  
  CONCLUSIONS
  The administration of the antioxidant vitamin C augments the inotropic response to dobutamine in humans. This suggests that redox environment contributes to the adrenergic regulation of ventricular contractility.
authors.affiliation: Bayer Cardiovascular Clinical Research Laboratory, Division of Cardiology, Mount Sinai Hospital, University of Toronto, Ontario, Canada. gary.newton@utoronto.ca
authors.forename: S
authors.initials: S
authors.lastname: Mak
authors.forename: G E
authors.initials: GE
authors.lastname: Newton
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D006328:Cardiac Catheterization; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003327:Coronary Disease / Q000628:therapy; D003331:Coronary Vessels; D003924:Diabetes Mellitus, Type 2 / Q000628:therapy; D004280:Dobutamine / Q000494:pharmacology*; D004357:Drug Synergism; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000628:therapy; D007261:Infusions, Intra-Arterial; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D010084:Oxidation-Reduction; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D000975:Antioxidants; D002316:Cardiotonic Agents; D004280:Dobutamine; D001205:Ascorbic Acid