GW274150 and GW273629 are potent and highly selective inhibitors of inducible nitric oxide synthase in vitro and in vivo.

1 GW274150 ([2-[(1-iminoethyl) amino]ethyl]-L-homocysteine) and GW273629 (3-[[2-[(1-iminoethyl)amino]ethyl]sulphonyl]-L-alanine) are potent, time-dependent, highly selective inhibitors of human inducible nitric oxide synthase (iNOS) vs endothelial NOS (eNOS) (>100-fold) or neuronal NOS (nNOS) (>80-fold). GW274150 and GW273629 are arginine competitive, NADPH-dependent inhibitors of human iNOS with steady state K(d) values of <40 and <90 nM, respectively. 2 GW274150 and GW273629 inhibited intracellular iNOS in J774 cells in a time-dependent manner, reaching IC(50) values of 0.