[Effects of protein disulfide isomerase on hyperglycemia and hypoxia/reoxygenation injury in H9c2 cardiomyocytes].

Objective: To explore the effect of protein disulfide isomerase (PDI) in diabetic ischemic heart disease. Methods: We established an in vitro model of high glucose and hypoxia/reoxygenation in H9c2 rat myocardial cells. Cultured cells were divided into four groups: Control, high glucose (HG), hypoxia/reoxygenation (H/R) and HG+H/R. Changes in PDI expression mediated by PDI adenovirus(Ad-PDI) infection and siRNA(PDI-siRNA) transfection in myocardial cells were observed by inverted fluorescence microscopy. We also measured lactate dehydrogenase(LDH) activity and malondialdehyde(MDA) and high molecular weight(HMW)-APN concentrations. PDI, APN, cleaved caspase-3, and glucose regulated protein 78 (Grp78) protein expression were detected. Results: PDI expression was significantly decreased in the HG, H/R and HG+H/R groups compared to the Control group; however, LDH activity[(179.7±10.4) U/L、(218.4±18.4) U/L、(328.2±5.3) U/L vs (91.0±11.0) U/L], MDA concentration[(7.0±0.4) µmol/L、(10.0±1.0) µmol/L、(11.7±1.0) µmol/L vs (4.2±1.8) µmol/L], cleaved caspase-3, and Grp78 expression were increased. Interestingly, APN and HMW-APN expression were decreased [(2.01±0.21) µg/L、(1.64±0.27) µg/L、(1.20±0.14) µg/L vs (2.62±0.12) µg/L, all P<0.05]. Over expression of PDI attenuated high glucose and hypoxia/reoxygenation induced apoptosis and oxidative stress in H9c2 cardiomyocytes(all P<0.05), and simultaneously increased APN and HMW-APN expression [(2.86±0.03) µg/L vs (3.03±0.10) µg/L、(2.06±0.05) µg/L vs (2.31±0.06) µg/L、(1.83±0.07) µg/L vs (1.96±0.11) µg/L、(1.20±0.06) µg/L vs (1.39±0.09) µg/L]. PDI-siRNA transfection increased LDH activity, MDA concentration, and cleaved caspase-3 and Grp78 expression, and decreased APN and HMW-APN expression [(0.75±0.09) µg/L vs (0.59±0.09) µg/L、(0.62±0.04) µg/L vs (0.53±0.05) µg/L、(0.55±0.14) µg/L vs (0.51±0.12) µg/L、(0.48±0.12) µg/L vs (0.35±0.08) µg/L] in response to different treatments in cultured H9c2 cardiomyocytes (all P<0.05). Conclusion: PDI may regulate the expression of APN and HMW-APN, and play an important role in the function of diabetic ischemia-reperfusion cardiomyocytes.