A: bar graphs showing responses to the iv injections of the vasodilators albuterol, isoproterenol, fasudil, histamine, and PGE1. B: iv injections of the vasoconstrictors U-46619, phenylephrine, and angiotensin II and acute ventilatory hypoxia (10% O2-90% N2 gas) on pulmonary and systemic arterial pressure and cardiac output before and after treatment with ODQ (5 mg/kg iv). n, No. of experiments. *P < 0.05 compared with control, paired analysis.