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Nitric oxide modulates right ventricular flow and oxygen consumption during norepinephrine infusion
Srinath Setty1, Johnathan D Tune, H Fred Downey
1Department of Integrative Physiology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699, USA. ssetty@hsc.unt.edu
American Journal of Physiology. Heart and Circulatory Physiology
|January 15, 2002
Summary
Nitric oxide (NO) aids norepinephrine-induced vasodilation in the right coronary artery. NO also enhances right ventricular oxygen efficiency, despite not altering oxygen consumption during norepinephrine infusion.
Area of Science:
- Cardiovascular Physiology
- Myocardial Metabolism
Background:
- Norepinephrine increases myocardial oxygen consumption (MVO2) and can affect coronary blood flow.
- The role of nitric oxide (NO) in modulating these effects in the right ventricle is not fully understood.
Purpose of the Study:
- To investigate NO's contribution to norepinephrine-induced right coronary vasodilation.
- To determine if NO influences the norepinephrine-induced increase in right ventricular MVO2.
Main Methods:
- Anesthetized, open-chest dogs were used.
- Measurements included aortic pressure, heart rate, right ventricular contractility (dP/dt), coronary blood flow, and MVO2.
- Norepinephrine was infused, with and without the NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME).
Main Results:
- Norepinephrine increased right coronary blood flow and MVO2.
- L-NAME blunted the coronary blood flow response to norepinephrine.
- L-NAME increased the oxygen cost of right ventricular function, indexed by heart rate x dP/dt x systolic pressure.
Conclusions:
- NO plays a significant role in norepinephrine-induced vasodilation of the right coronary artery.
- NO improves the efficiency of oxygen utilization in the right ventricle during norepinephrine administration.