NOS3 and endothelial dysfunction: Wang et al. demonstrated that Indinavir, at a clinical plasma concentration, can cause endothelial dysfunction through eNOS (endothelial nitric oxide synthase) down-regulation in porcine pulmonary artery rings and HPAECs (human pulmonary arterial endothelial cells), and that endothelium-dependent relaxation of the vessel rings was also reduced following Indinavir treatment [83].