Fig. 4. Effects of isoflurane pretreatment on nitrite production induced by lipopolysaccharide (LPS) plus interferon γ (IFN-γ). Rat NR8383 macrophages were pretreated with or without 2% isoflurane (2% iso). They were then exposed to 100 ng/ml LPS plus 50 U/ml IFN-γ for 24 h at 30 min after the isoflurane pretreatment (Isopre). The culture medium was collected for nitrite measurement. Results are mean ± SD (n = 5). * P < 0.05 compared with the control cells. # P < 0.05 compared with the cells incubated with LPS plus IFN-γ.