Fig. 4.

Inhaled NO is a selective pulmonary vasodilator with actions on the systemic vasculature. A schematic of an alveolar-capillary unit is presented highlighting the ability of inhaled NO to dilate pulmonary arterioles and reduce pulmonary artery pressure (PAP). Although inhaled NO does not dilate systemic arterioles or alter systemic arterial pressure (SAP) under normal conditions, inhaled NO does have systemic effects which are described in the text and may be mediated by circulating cells exposed to NO in the lungs and blood-borne NO derivatives: SNO-proteins — S-nitroso proteins including SNO-albumin; SNO-Hb — S-nitroso-hemoglobin (nitrosylated on Cys⁹³ of the β chain); NO-Fe-Hb – nytrosyl-hemoglobin; and nitrite.