Nitric oxide modulates right ventricular flow and oxygen consumption during norepinephrine infusion.
This study was designed to test if nitric oxide (NO) contributes to norepinephrine-induced right coronary vasodilation and if NO blunts the norepinephrine-induced increase in myocardial oxygen consumption (MVO(2)) in the right ventricle. In five anesthetized, open-chest dogs, mean aortic pressure, heart rate, right ventricular rate of pressure development over time (dP/dt), right coronary blood flow, and right ventricular MVO(2) were measured before and during graded intracoronary infusions of norepinephrine in the absence and presence of a NO synthase blocker, N(omega)-nitro-L-arginine methyl ester (L-NAME; 150 microg/min i.c.). During both conditions, right coronary blood flow and right ventricular MVO(2) significantly increased with graded infusions of norepinephrine. L-NAME significantly blunted the coronary hyperemic response to norepinephrine, although L-NAME did not alter the relationship between right ventricular MVO(2) and norepinephrine dose. However, when right ventricular function was indexed by heart rate x right ventricular maximum dP/dt x peak right ventricular systolic pressure, L-NAME significantly increased the oxygen cost of right ventricular function. These results indicate that NO contributes to norepinephrine-induced right coronary vasodilation and improves right ventricular oxygen utilization efficiency.
Setty
Srinath
S
Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699, USA. ssetty@hsc.unt.edu
Tune
Johnathan D
JD
Downey
H Fred
HF
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D017942:Nitric Acid / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000502:physiology*; D012044:Regression Analysis; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D016278:Ventricular Function, Right
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D017942:Nitric Acid; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine