NO IN PULMONARY-ARTERY HYPERTENSION

Endothelium-derived nitric oxide (NO) is a powerful pulmonary vasodila tor which also prevents adhesion and agregation of platelets, controls growth of smooth muscle and influences the expression of growth promo ting and vasoactive substances. Impaired endothelial NO production con tributes to pulmonary vasoconstriction and vascular remodeling in seve ral forms of pulmonary hypertension, notably neonatal and hypoxic pulm onary hypertension. While chronic NO inhibition in utero produces pers istent pulmonary hypertension in newborn lambs, chronic inhalation of NO in rats exposed to hypoxia opposes development of pulmonary hyperte nsion. Exogenous NO gas delivered via the airspaces is a selective pul monary vasodilator now employed as therapy in various lung disorders.