Objective     To study the expression change of endoplasmic reticulum stress proteins and inflammatory cytokines during hypoxia/reoxygenation in rat renal tubular epithelial cell line NRK-52E

and to discuss the relationship between endoplasmic reticulum stress and hypoxia/reoxygenation-induced inflammation in NRK-52E cells.     Methods    NRK-52E

cells were cultured in DMEM containing 5% fetal bovine serum in a thermostatic incubator (37  C

5% CO

2

). The cells were divided into a normal control group and a hypoxia/reoxygenation (H/R) group. LDH activity in the supernatant of cell culture media was tested with an automatic biochemical analyzer. The expression of glucose-regulated protein 78 (GRP78) and of CCAAT/enhancer-binding protein homologous protein (CHOP) was detected with Western blot analysis. The IL-β level in the supernatant of cell culture media was measured with ELISA.     Results    LDH activity in the supernatant of cell culture medium of the H/R group (45.93±6.42 U/L) increased significantly

as compared with that of the control group (22.07±1.23 U/L) (

P

<

0.05). GRP78 expression level (GRP78/β-actin) and CHOP expression level (CHOP/β-actin) in the cells of the H/R group was 1.24±0.04 and 1.19±0.05

respectively

significantly higher than those of the control group 0.80±0.04 (

P

<

0.05) and 0.81±0.05 (

P

<

0.05)

respectively. The IL-β level in the H/R group (14.93±2.26 pg/ml) had a remarkable difference from that in the control group (6.55±2.03 pg/ml) (

P

<

0.01).     Conclusion    Hypoxia/reoxygenation can induce endoplasmic reticulum stress and inflammation in rat renal tubular epithelial cells. CHOP expression up-regulated by endoplasmic reticulum stress is probably important in the hypoxia/reoxygenation-induced inflammation in renal tubular epithelial cells.