Figure 1. Effects of N-methyl-L-arginine (20 mg/kg intravenous) on mean arterial pressure, cardiac output, and systemic vascular resistance in awake dogs (open square) and anesthetized with 1.2% halothane (open circle). St = Steady - state control before N-methyl-L-arginine injection; *P < 0.05 versus control. P < 0.05 versus the magnitude of changes induced by N-methyl-L-arginine in awake dogs.