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Blockade of nitric oxide synthesis reduces myocardial oxygen consumption in vivo.
- Source :
-
Circulation [Circulation] 1997 Mar 04; Vol. 95 (5), pp. 1328-34. - Publication Year :
- 1997
-
Abstract
- Background: Although cardiac myocytes and coronary vascular endothelium are known to express a constitutive form of NO synthase, the in vivo effects of tonic endogenous production of NO on myocardial O2 consumption and contractile performance remain unclear.<br />Methods and Results: The effects of blockade of NO synthase were determined in intact dogs. Myocardial O2 consumption decreased systematically over a wide range of hemodynamic demand after the systemic administration of N omega-nitro-L-arginine methyl ester (L-NAME) or N omega-nitro-L-arginine. Decreases after doses of 1 and 10 mg/kg L-NAME averaged 23 +/- 3.8% and 34 +/- 7.2% at a heart rate of 90 bpm in open-chest animals. Similar reductions occurred after the administration of L-NAME and N omega-nitro-L-arginine in chronically instrumented animals and were unaffected by beta-adrenergic blockade. Intracoronary infusion of L-NAME in chronically instrumented animals reduced both myocardial O2 consumption and regional segment shortening, even at a dose that did not increase systemic arterial pressure.<br />Conclusions: The blockade of NO synthesis reduces myocardial O2 consumption in vivo. The decrease in O2 consumption is accompanied by a decrease in segment shortening. It involves a direct myocardial action of NO, is unaffected by beta-blockade, and is consistent with in vitro studies indicating that low levels of NO augment contractile performance by inhibition of a cGMP-dependent phosphodiesterase.
- Subjects :
- Animals
Blood Pressure drug effects
Carbon Dioxide blood
Coronary Circulation drug effects
Dogs
Heart physiology
Heart Rate drug effects
Myocardial Contraction drug effects
Nitric Oxide physiology
Oxygen blood
Ventricular Function, Left drug effects
Enzyme Inhibitors pharmacology
Heart drug effects
Hemodynamics drug effects
Myocardium metabolism
NG-Nitroarginine Methyl Ester pharmacology
Nitric Oxide Synthase antagonists & inhibitors
Nitroarginine pharmacology
Oxygen Consumption drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0009-7322
- Volume :
- 95
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Circulation
- Publication Type :
- Academic Journal
- Accession number :
- 9054867
- Full Text :
- https://doi.org/10.1161/01.cir.95.5.1328