Fig. 1.

Lipopolysaccharide/tumor necrosis factor-α (LPS/TNF) treatment induces inducible nitric oxide synthase (iNOS) and arginase II in bovine pulmonary arterial endothelial cells (bPAEC). bPAEC were incubated for 24 h in the presence of either vehicle or LPS/TNF. After 24 h, the cells were harvested for mRNA. A: under the conditions of our study, treatment with LPS/TNF resulted in a threefold increase in mRNA for iNOS. B: LPS/TNF treatment resulted in a decrease in endothelial nitric oxide synthase (eNOS) mRNA expression. n = 4 in each group. C: LPS/TNF treatment had no significant effect on arginase I mRNA expression. D: LPS/TNF treatment resulted in significantly greater arginase II mRNA levels. Values are means ± SE; n = 4 in each group. *LPS/TNF different from control, P < 0.005. E: Since there was a large variation in arginase I mRNA expression in these bPAEC, we performed Western blotting on cell protein lysates from a separate set of experiments in bPAEC treated for 24 h with either vehicle (control) or LPS/TNF. Mirroring the mRNA results, arginase I protein levels were not different between control and LPS/TNF-treated bPAEC, while arginase II protein expression was substantially greater in LPS/TNF-treated bPAEC than in control bPAEC.