缺氧诱导因子-1在缺氧预处理心肌保护中的作用及其机制研究

Role of hypoxia- inducible factor-1 in cardioprotection of hypoxic preconditioning

目的:研究缺氧诱导因子-1(HIF-1)在缺氧预处理(HPC)心肌细胞保护中的作用及其机制。方法:在培养的SD乳鼠心肌细胞缺氧/复氧(H/R)模型上,观察HPC对于24h后心肌细胞H/R损伤的影响,以MTT法测定心肌细胞存活率,试剂盒测定培养液中乳酸脱氢酶(LDH)活性。制备心肌细胞蛋白提取物,以磷酸化的细胞外信号调节激酶(ERK1/2)抗体测定HPC后不同时间ERK1/2活性,以聚丙烯酰胺电泳迁移实验观察HIF-1α磷酸化,并观察蛋白磷酸酶激动剂BDM和ERKs的上游激酶(MEK1/2)抑制剂PD98059对于HPC诱导的HIF-1α磷酸化以及心肌细胞保护作用的影响。结果:HPC可以提高心肌细胞H/R后存活率、减少LDH漏出,并激活ERK1/2,使HIF-1α发生磷酸化;蛋白磷酸酶激动剂BDM和ERKs的上游激酶MEK抑制剂PD98059可以消除HPC诱导的HIF-1α磷酸化和心肌细胞保护作用。结论:HPC可以提高乳鼠心肌细胞对于H/R的耐受性,其机制涉及ERKs介导的HIF-1α磷酸化。

AIM: To investigate the effects of hypoxia-inducible factor-1 (HIF-1) on cardioprotection of hypoxic preconditioning (HPC) and its mechanisms. METHODS: In the model of hypoxia/reoxygenation (H/R) of cardiomyocytes from neonatal Spargue-Dawley rats, delayed cardioprotective effects of HPC on lethal H/R were observed. Whole cell extracts were prepared for determining activities of extracellular signal-regulated protein kinases (ERKs) and HIF-1α phosphorylation. RESULTS: HPC significantly promoted survival and membrane integrity of cardiomyocytes subjected to sustained H/R. SDS-PAGE mobility shift experiments showed increased phophorylation level of HIF-1α in hypoxic preconditioned cardiomyocytes. ERK1/2 were activated at 10 min after HPC and returned to the control level at 60 min. CONCLUSION: HPC protects neonatal cardiomyocytes from H/B injury. HIF-1α phosphorylation induced by ERKs might contribute to the cardioprotection of HPC.