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This Article Full Text Full Text (PDF) All Versions of this Article: 289/6/H2424    most recent 00453.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Mak, S. Articles by Newton, G. E. Search for Related Content PubMed PubMed Citation Articles by Mak, S. Articles by Newton, G. E.

Effect of vitamin C and L-NMMA on the inotropic response to dobutamine in patients with heart failure

Cardiovascular Clinical Research Laboratory, Division of Cardiology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada

Submitted 5 May 2005 ; accepted in final form 15 July 2005

The positive effect of vitamin C on left ventricular (LV) inotropic responses to dobutamine, observed in patients with preserved LV function, is lost in heart failure (HF). We tested the hypothesis that in HF, endogenous nitric oxide (NO) opposes the positive effect of vitamin C on adrenergically stimulated contractility by examining the effects of vitamin C on dobutamine responses during NO synthase inhibition. In 11 HF patients, a micromanometer-tipped catheter was inserted into the LV and an infusion catheter was positioned in the left main coronary artery. The peak positive rate of change of LV pressure (LV +dP/dt) was measured in response to intravenous dobutamine (Dob-1). After recontrol, intracoronary N^G-monomethyl-L-arginine (L-NMMA) was infused before reinfusion of dobutamine (L-NMMA + Dob-2). Finally, intracoronary vitamin C was infused in addition to intracoronary L-NMMA and dobutamine (L-NMMA + Dob-2 + vitamin C). Intracoronary L-NMMA alone had no effect on LV +dP/dt. After a stable inotropic response to intracoronary L-NMMA and dobutamine was established, the addition of intracoronary vitamin C resulted in a modest but significant increase in LV +dP/dt. The change in LV +dP/dt in response to dobutamine alone was 25 ± 5%, with intracoronary L-NMMA, 27 ± 6%, and with intracoronary L-NMMA plus vitamin C, 37 ± 5% (P < 0.05 vs. Dob-1 and L-NMMA + Dob-2). These findings demonstrate that an interaction between endogenous NO and redox environment exists and exerts some influence on stimulated contractility in HF.

antioxidants; nitric oxide