Fig. 4. ( A ) Mean arterial pressure (MAP), ( B ) mean pulmonary arterial pressure (PAP), ( C ) systemic vascular resistance (SVR), ( D ) pulmonary vascular resistance (PVR), ( E ) cardiac output, and ( F ) plasma methemoglobin concentration of awake lambs after infusion of 37°C autologous whole blood (12 ml/kg) (n = 6), after intravenous HBOC-201 (n = 5) or HBOC-201 (12 ml/kg) after pretreatment with a sodium nitrite infusion (1 mg/kg over 5 min; n = 4). * P < 0.05; HBOC-201 differs from autologous blood and from HBOC-201 after nitrite. † P < 0.05; autologous whole blood differs from HBOC-201 with or without nitrite infusion. § P < 0.05; differs from before nitrite administration. HBOC = hemoglobin-based oxygen-carrying solution.