Reduced endothelial dependent vasodilation in vessels from TLR4−/− mice is associated with increased superoxide generation

► The absence of TLR4 is associated with reduced endothelial cell function in mesenteric arteries. ► TLR4−/− mouse arteries have reduced acetylcholine responses. ► TLR4−/− have increased superoxide levels when stimulated with acetylcholine. ► An increase in superoxide generation reduces the activity of endothelial derived nitric oxide.