Objective      To investigate the protective effect of isoflurane on H9c2 cell injury induced by hypoxia-reoxygenation via Nrf2-ARE signaling pathway.       Methods      H9c2 cells were cultured and divided into control group

hypoxia-reoxygenation group

isoflurane pre-treatment group

Nrf2 siRNA transfection group

nonspecific transfection group (scramble group)

nonspecific transfection with isoflurane pretreatment group

and Nrf2 siRNA transfection with isoflurane pretreatment group. Cell viability and apoptosis were evaluated by MTT assay and TUNEL assay

respectively. The levels of MDA and GSH were tested with TBA method and spectrophotometric method. qRT-PCR and Western blotting were performed to detect the expression of Nrf2

HO-1 and NQO1 at mRNA and protein levels.       Results      Compared with the control group

the decreased cell viability

increased cell apoptosis

raised MDA level

and descended GSH level were observed in the hypoxia-reoxygenation group. Meanwhile

both of the mRNA and protein levels of Nrf2

HO-1 and NQO1 were remarkably down-regulated in the hypoxia-reoxygenation group compared with the control group (P0.05). Isoflurane pre-treatment significantly improved H9c2 cell viability

reduced the number of apoptotic cells

decreased MDA level and increased GSH level compared with the hypoxia-reoxygenation group (P0.05). Furthermore

the mRNA and protein levels of Nrf2

HO-1 and NQO1 in H9c2 cells were also up-regulated after isoflurane treatment (P0.05). Compared with the hypoxia-reoxygenation group and the scramble group

the expression of Nrf2 in the siRNA transfection group was significantly decreased (P0.05)

and 2% isoflurane had no significant effect on the expression of Nrf2. The cell viability was significantly decreased

and apoptotic cells were notably increased in the Nrf2 siRNA transfection with isoflurane pretreatment group compared with the control group

isoflurane pretreatment group and nonspecific transfection with isoflurane pretreatment group (P0.05). Meanwhile

the MDA level was notably up-regulated

and the GSH level was remarkably down-regulated in the Nrf2 siRNA transfection with isoflurane pretreatment group.       Conclusion      The protective effect of isoflurane on hypoxia-reoxygenation-injured H9c2 cells is confirmed

and it is possibly related with the activation of Nrf2-ARE signaling pathway.