We recently demonstrated that the lipid mediator leukotriene B4 (LTB4) produced by infiltrating macrophages in pulmonary hypertension lungs induced EC apoptosis via suppression of endothelial nitric oxide synthase (eNOS); LTB4 was found to induce significant EC apoptotic death in a dose-dependent manner within 24 h of culture [62]. Here, NOS3 is linked to pulmonary arterial hypertension.