Effect of inhaled nitric oxide on cardiovascular response to catecholaminein heart failure

We examined the dose responses to continuous infusion of isoproterenol (ISO ) and norepinephrine (NE) in normal (control) and procainamide-induced hear t failure dogs with or without inhalation of 70 ppm nitric oxide (NO). Inha led NO affected neither left Ventricular (LV) function nor hemodynamics at baseline in both control and heart failure dogs. There were no significant differences in the responses to ISO and NE with or without inhaled NO in th e control. The responses of LV dP/dt to ISO and NE were significantly enhan ced in heart failure; however, they were not affected by inhaled NO. In con trast, LV pressure and dimension at end diastole were sig significantly inc reased, and pulmonary vascular resistance (PVR) was significantly decreased by inhaled NO during infusion of both ISO and NE in heart failure. In conc lusion the positive inotropic response to cathecholamine is not affected by inhaled NO even in heart failure. Inhaled NO decreases PVR, but potentiall y increases LV preload in the presence of additional stress of cathecholami ne in heart failure.