Figure 1.

TNFα-induced iNOS expression in 3T3-F442A. (a) Preadipocytes and 10 days-differentiated 3T3-F442A cells were treated or not for 20 h with TNFα (20 ng ml⁻¹). Protein extracts were analysed by Western blot using specific NOS antibodies. Representative blots from three independent experiments are shown. A protein extract from murine macrophages (RAW 264.7) treated with a mixture of IFNγ (10 ng ml⁻¹) plus LPS (1 μg ml⁻¹) was used as a positive control for iNOS. (b) TNFα-induced nitrite production on preadipocytes and differentiated adipocytes. Results are expressed as mean±s.e.m. from three independent experiments performed in duplicate. $ indicates a statistically significant difference between control and TNFα-treated cells, while * indicates a statistically significant difference between preadipocytes and differentiated adipocytes (one-way ANOVA followed by a Dunnett's post hoc test, P<0.05). (c) TNFα-induced nitrite production in differentiated adipocytes and NO-synthase inhibition. Results are expressed as mean±s.e.m. from three independent experiments performed in duplicate. * indicates a statistically significant difference induced by the treatment with L-NAME (one-way ANOVA followed by a Dunnett's post hoc test, P<0.05). Complete inhibition of TNFα-induced nitrite production was also obtained with aminoguanidine (1 mM) or S-methyl-isothiourea (1 mM; data not shown).