TNF and acute respiratory distress syndrome: Interestingly, selective inhibition of iNOS in vitro with 10 μM L-NIL (Figure 6C) or in vivo inhibition of TNF-α by etanercept (Figure 6D) completely restored contractile response to phenylephrine in endothelium-intact aortic rings from ALI animals, as seen with endothelial removal and L-NAME.