[Physiopathology of pulmonary arterial hypertension. Cellular and molecular aspects]

The combined effects of vasoconstriction, remodelling of the pulmonary vessel walls and in situ thrombosis contribute to the increase in pulmonary vascular resistance during pulmonary arterial hypertension. Vascular remodelling involves all the sheaths of the vessel wall and all the cell types of which it is composed (endothelial cells, smooth muscle cells, fibroblasts, inflammatory cells and platelets). Excessive vasoconstriction has been related to a defect in the function of expression of the potassium channels and endothelial dysfunction. This leads to chronic insufficiency in the production of vasodilators, notably nitrogen monoxide and prostacyclin and the excessive production of vasoconstrictors such as endotheline-1. These defects contribute to the increase in vascular tonus and pulmonary vascular remodelling and represent pertinent pharmacological targets. Certain growth factors, including those of the super-family of transforming growth factor beta, angiopoietine-1 and serotonin, may play a part in the pathogenesis of pulmonary arterial hypertension.