[Effect of nitric oxide on NF-kappaB activation induced by cigarette smoke extract in rat alveolar macrophage]

To explore the effect of nitric oxide on NF-kappaB activation in rat alveolar macrophage(AM) induced by cigarette smoke extract(CSE) and the involved mechanism.

AMs were co-cultured with NO precursor L-arginine (L-Arg) or inhibitor of inducible nitric oxide synthase L-N(6)(1-iminoethyl)lysine (L-NIL) and CSE. The expression of NF-kappaB was determined by immunocytochemistrical staining, the content of I-kappaB protein was detected by Western blot, the level of NO in supernatant was assayed by Griess reaction.

CSE could induce NF-kappaB activation and decrease level of I-kappaB. L-Arg augmented CSE-induced NF-kappaB activation and decreased I-kappaB content at low concentration while inhibited CSE-induced NF-kappaB activation at high concentration, but there was not any significant difference of the expression of I-kappaB. The percentage of NF-kappaB nucleus dyeing positive cells was lower and the expression of I-kappaB was higher in response to CSE plus various concentrations of L-NIL as compared with that in response to CSE alone (P<0.01). The changes induced by L-NIL were concentration-dependent.

NO may up-regulate and down-regulate the activation of NF-kappaB induced by CSE according to difference in NO concentration in AMs.