ABSTRACT
Objective: To investigate the effect and mechanism of helix B surface peptide (HBSP) on myocardial ischemia reperfusion injury (MIRI) in experimental mice. Methods: The MIRI model was established by ligation of anterior descending coronary artery of the mice for 45 min and followed by corresponding treatment at 5 min before reperfusion. A total of 64 male ICR mice were randomly assigned to 4 group:①Sham group,②MIRI group, the mice received normal saline at 5 min before reperfusion,③HBSP group, MIRI mice received HBSP at 5 min before reperfusion and④HBSP+PD98059 group, MIRI mice received PD98059 (a speciifc blocker of ERK1/2) at 20 min before reperfusion and followed by HBSP at 5 min before reperfusion.n=16 in each group, all animals were treated for 2 hours. The area of myocardial infarction (MI) was detected by TTC-EB double staining method, the myocardial apoptosis rate was examined by TUNEL method, the levels of protein expression of ERK1/2 and phosphorylation of ERK1/2 were measured by Western blot analysis. Results: Compared with MIRI group, HBSP group presented decreased MI area, decreased myocardial apoptosis rate and increased phopsphorylation level of ERK1/2, allP Conclusion: HBSP may reduce the MI area via inhibiting myocardial apoptosis and therefore, protecting the experimental mice from MIRI; the mechanism might be related to the activation of ERK1/2 pathway.
ABSTRACT
Objective To observe the expression of caspase-3 and transposition of Omi/HtrA2 in H9C2 by erythropoietin and/or Omi/HtrA2 silencing to explore the related anti-apoptotic mechanisms.Methods The cultured H9C2 cardiomyocytes were divided into control group,H/R group (anoxia 2 h and re-oxygenation 24 h), and different concentrations of EPO treatment groups.The release rate of lactate dehydrogenase (LDH)in cell supernatant was measured in each group.Expressions of cleaved caspase-3 and Omi/HtrA2 were measured by Western blot;then the transposition of Omi/HtrA2 between cytoplasm and mitochondria was observed.Specific siRNA interfering fragment was transfected into H9C2 cardiomyocytes by liposome method.Its silencing effect on Omi/HtrA2 was measured by RT-PCR and Western blot.The survival rate,release rate and expression of cleaved caspase-3 were measured.And the expression of Omi/HtrA2 was measured in cytoplasm and mitochondria in H9C2 (transposition of Omi/HtrA2 ).Results Compared with H/R group,the release of LDH and expression of cleaved caspase-3 were decreased; the transposition of Omi/HtrA2 from mitochondria to cytoplasm in H/R treatment groups was increased compared with control group,while that in EPO (20 IU/mL)group decreased.si-HtrA2 group transfected with siRNA showed a decreased release of LDH and expression of cleaved caspase-3 with all significant variances (P <0.05).Conclusion EPO exerts a cytoprotective effect by inhibiting the transposition of Omi/HtrA2 and hence the activation of caspases-3 pathway.