The Relationship Between Hypoxia Inducible Factor-1and Heme Oxygenase-1in Hypoxia/Reoxygenation Injury Of H9C2Cardiomyocytes

Objective:To investigate the relationship and role of hypoxia inducible factor-1(HIF-1) andheme oxygenase-1(HO-1) in hypoxia/reoxygenation(H/R) injury of H9C2cardiom-yocytes.Methods:(1).The H9C2cardiomyocytes were cultured to subconfluence in vitro andsubjected to hypoxia/reoxygenation(10h/6h).(2).The cultured cells were randomly allocated to the following treatmentgroups: normal group, H/R group, the H/R plus YC-1(an inhibitor of HIF-1activation) group, the H/R plus DMOG(an inducer of HIF-1activation) group, theH/R plus ZnPP IX(an inhibitor of HO-1activation)group, the H/R plus Hemin(aninducer of HIF-1activation) group.(3).HIF-1and HO-1levels were determined by Western blotting and reversetranscription polymerase chain reaction,respectively. cardiomyocytes apoptosis andviability were assessed by Annexin V/FITC apoptosis and MTT assay, respectively.cardiac injury was evaluated by LDH leakage and MDAlevels.Results:(1).Compared with the H/R group, pretreatment with HO-1inducer Heminreduced cell apoptosis(9.67±1.62%vs20.93±2.66%,p<0.05),LDH activity(75.13±4.75IU/L vs104.93±11.89IU/L,p<0.05),and MDA levels(2.41±0.26nmol/ml vs3.41±0.12nmol/ml,p<0.05),as well as increased cell survival(82.54±2.07%vs44.98±2.20%,p<0.05);while pretreatment with HO-1inhibitor ZnPP increased cellapoptosis(38.91±2.57%vs20.93±2.66%,p<0.05), LDH activity (135.97±5.14IU/L vs104.93±11.89IU/L,p<0.05),and MDA levels(4.82±0.43nmol/ml vs3.41±0.12nmol/ml,p<0.05),as well as reduced cell survival(35.43±1.13%vs44.98±2.20%,p<0.05). (2).Compared with the H/R group,pretreatment with HIF-1inducer DMOGreduced cell apoptosis(11.93±1.72%vs20.93±2.66%,p<0.05),LDH activity(77.53±2.66IU/L vs104.93±11.89IU/L,p<0.05),and MDA levels(2.36±0.08nmol/ml vs3.41±0.12nmol/ml,p<0.05), as well as increased cell survival(78.13±1.69%vs44.98±2.20%,p<0.05);while pretreatment with HIF-1inhibitor YC-1increased cellapoptosis(44.01±3.76%vs20.93±2.66%,p<0.05), LDH activity(151.33±4.19IU/L vs104.93±11.89IU/L,p<0.05),and MDA levels(5.22±0.18nmol/ml vs3.41±0.12nmol/ml,p<0.05),as well as reduced cell survival(30.61±2.00%vs44.98±2.20%,p<0.05).(3).Compared with the normal group, the protein and mRNA levels of HIF-1andHO-1were significantly increased in H/R group(p <0.05);(4).Compared with the H/R group, the protein levels of HIF-1and HO-1weresignificantly increased in H/R plus DMOG group(p<0.05); the protein levels of HIF-1and HO-1were significantly reduced in H/R plus YC-1group(p<0.05); the proteinand mRNAlevels of HO-1were significantly increased（p<0.05）,whereas the proteinand mRNA levels of HIF-1were not changed in Hemin plus H/R group(p>0.05);theprotein and mRNA levels of HO-1were significantly reduced（p<0.05）,whereas theprotein and mRNA levels of HIF-1were not changed in ZnPP plus H/Rgroup(p>0.05);Conclusion:(1).HO-1has the potential to exert protective effects against hypoxia/reoxy-genation injury of H9C2cardiomyocytesvia via anti-apoptosis and anti-oxidativestress.(2).HIF-1has also the potential to exert protective effects against hypoxia/reoxygenation injury of H9C2cardiomyocytes via anti-apoptosis and anti-oxidativestress.(3).HIF-1can effect the expression of HO-1in hypoxia/reoxygenation injury ofH9C2cardiomyocytes,whereas HO-1doesn,t have effect on HIF-1.