Huang Yi-Feng, Gong Kai-Zheng, Zhang Zhen-Gang
Department of Cardiology, The 2nd Clinical Medical College of Yangzhou University, Yangzhou 225001.
Sheng Li Xue Bao. 2003 Aug 25;55(4):454-8.
Preconditioning (PC) exhibits earlier and delayed protection. But the mechanism of cellular signaling in delayed protection of PC remains unclear. We explored the roles of ERK(1/2) and p38 MAPK(alpha/beta) (p38(alpha/beta)) in delayed protection of anoxia preconditioning (APC). The anoxia/reoxygenation (A/R) injury and APC models were established in cultured neonatal rat cardiomyocytes. An ERK(1/2) inhibitor (PD98059) and a p38(alpha/beta) blocker (SB203580) were applied and their effects on A/R and APC models were observed. The cellular contents of MDA, SOD, cell viability and LDH release was measured at the end of the study. ERK(1/2) and p38 MAPK total activity was measured by in-gel myelin basic protein phosphorylation assay at different points during sustained anoxia. The results obtained are as follows: (1) PD98059 (but not SB203580), administered in preconditioning anoxia phase in APC group, abolished completely the delayed protection of APC; (2) SB203580 administered in sustained anoxia phase in A/R group could relieve cell injury induced by anoxia, but not by PD98059; (3) the highest activity of ERK(1/2) and p38 MAPK induced by anoxia appeared at 4 h after the beginning of sustained anoxia. APC inhibited the over activation of both ERK(1/2) and p38 during the following sustained anoxia. These results suggest that ERK(1/2) activation during preconditioning may be an important link of cell signal transduction in the mechanism of APC delayed protection. p38(alpha/beta) activation at the preconditioning stage dose not participate in signaling of APC delayed protection. The excessive activation of p38(alpha/beta) is possibly a key factor in mediating cell injury induced by sustained anoxia. The inhibition of p38(alpha/beta) excessive activation during subsequent sustained anoxia might play a role in delayed protection mechanism of APC.
预处理（PC）具有早期和延迟保护作用。但PC延迟保护中的细胞信号传导机制仍不清楚。我们探讨了细胞外信号调节激酶（ERK）（1/2）和p38丝裂原活化蛋白激酶（α/β）（p38（α/β））在缺氧预处理（APC）延迟保护中的作用。在培养的新生大鼠心肌细胞中建立缺氧/复氧（A/R）损伤和APC模型。应用ERK（1/2）抑制剂（PD98059）和p38（α/β）阻滞剂（SB203580），观察它们对A/R和APC模型的影响。在研究结束时测量丙二醛（MDA）、超氧化物歧化酶（SOD）的细胞含量、细胞活力和乳酸脱氢酶（LDH）释放。在持续性缺氧期间的不同时间点，通过凝胶内髓鞘碱性蛋白磷酸化测定法测量ERK（1/2）和p38丝裂原活化蛋白激酶的总活性。获得的结果如下：（1）在APC组的预处理缺氧阶段给予PD98059（而非SB203580），可完全消除APC的延迟保护作用；（2）在A/R组的持续性缺氧阶段给予SB203580可减轻缺氧诱导的细胞损伤，但PD98059无此作用；（3）缺氧诱导的ERK（1/2）和p38丝裂原活化蛋白激酶的最高活性出现在持续性缺氧开始后4小时。APC在随后的持续性缺氧期间抑制了ERK（1/2）和p38的过度激活。这些结果表明，预处理期间ERK（1/2）的激活可能是APC延迟保护机制中细胞信号转导的重要环节。预处理阶段p38（α/β）的激活不参与APC延迟保护的信号传导。p38（α/β）的过度激活可能是介导持续性缺氧诱导的细胞损伤的关键因素。在随后的持续性缺氧期间抑制p38（α/β）的过度激活可能在APC的延迟保护机制中起作用。
