Fig. 2.
(A) Dose response of NAM versus NAM N-oxide production by HLMs (Km = 2.98 mM, Vmax = 60.14 pmol/mg per minute). (B) NAM N-oxide production by HLMs is not significantly inhibited by heat in the absence of NADPH (substrate NAM at 2 mM). (C) Effect of selective P450 inhibitors against major hepatic P450 enzymes on NAM N-oxide production (100 μM diethyldithiocarbamate, CYP2E1; 1 μM tranylcypromine, CYP2A6; 100 μM fluconazole, CYP2C9; 10 μM ketoconazole, CYP3A4; 100 μM α-naphthoflavone, CYP1A2; 1 μM quinidine, CYP2D6; and 300 μM orphenadrine, CYP2B6). Substrate NAM was at 2 mM. Mean ± S.D. of triplicate determinations. *P < 0.05 by Student’s t test.