Clinical perspective of hypoxia-mediated pulmonary hypertension.

Pulmonary hypertension is a condition associated with a variety of pulmonary disorders whose common denominator is alveolar hypoxia. Such disorders include chronic obstructive pulmonary disease, pulmonary fibrosis, sleep-disordered breathing, and exposure to high altitude. Acute hypoxia is characterized by vasoconstriction of small pulmonary arteries, a phenomenon called hypoxic pulmonary vasoconstriction. With prolonged hypoxia, thickening of the smooth vascular layer of the small pulmonary arteries occurs, a phenomenon described as pulmonary vascular remodeling. Although the core mechanisms of both vasoconstriction and remodeling are thought to reside in the smooth muscle cell layer, the endothelium modulates these two processes. The purpose of this review is briefly to (a) discuss the mechanisms of hypoxic pulmonary hypertension as it pertains to certain disease states, and (b) examine the pathways that have potential therapeutic applications for this condition.