COPD also includes a gradual increase in pulmonary arterial pressure, and 20–91% (depending on the definition, severity and measurement of COPD) have developed pulmonary hypertension.105 Endothelin-1 (ET-1) is an effective vasoconstrictor produced by endothelial cells, which can stimulate the contraction and proliferation of vascular smooth muscle cells. This evidence concerns the gene EDN1 and pulmonary hypertension.