ERK信号蛋白在吗啡预处理减轻大鼠全心缺血/再灌注损伤中的作用

Role of ERK signaling protein in morphine preconditioning reducing global ischemia-reperfusion injury in isolated rat hearts

目的探讨细胞外信号调节激酶(extracellular signaling-regulated kinase,ERK)在吗啡预处理减轻大鼠全心缺血/再灌注损伤中的作用。方法健康成年♂SD大鼠,采用随机数字表法分为6组(n=10):对照组(control,CON)、缺血/再灌注组(ischemia/reperfusion,I/R)、缺血预处理组(ischemia preconditioning,IPC)、吗啡1μmol·L^(-1)预处理组(morphine preconditioning,MPC)、MPC+ERK抑制剂PD98059组(MPD)、ERK抑制剂PD98059对照组(PD)。利用Langendorff灌流系统对各组大鼠离体心脏在进行相应处理后,化学比色法检测基线、再灌注5、10 min时冠脉流出液乳酸脱氢酶(lactate dehydrogenase,LDH)活性;同时利用充水球囊置入左心室持续监测左心室发展压(left ventricular developed pressure,LVDP)。2,3,5-氯化三苯基四氮唑(triphenyltetrazolium chloride,TTC)染色测量梗死区(infarct size,IS)、缺血危险区(area at risk,AAR)体积及IS/AAR比值;Western blot检测心肌组织ERK磷酸化水平。结果与I/R组比较,MPC组IS和IS/AAR减小,再灌注5、10 min时LDH活性降低,再灌注结束时LVDP升高,心肌组织磷酸化ERK(p-ERK)相对表达量增加;ERK抑制剂PD98059阻断MPC的保护作用,增加心肌梗死面积,升高再灌注5、10 min时LDH活性,降低再灌注末LVDP,此外,PD98059抑制MPC诱导的ERK磷酸化。结论吗啡预处理可能通过诱导ERK磷酸化水平升高而减轻大鼠全心缺血/再灌注损伤。

Aim To observe the role of ERK signaling protein in morphine preconditioning reducing global ischemia-reperfusion injury in isolated rat hearts. Methods Adult male Sprague-Dawley rats were distributed into six groups( n = 10 for each) using a random number table: control group( CON),ischemia-reperfusion group( I/R),ischemia preconditioning group( IPC),morphine preconditioning group at the concentration of1 μmol·L^(-1)( MPC),ERK inhibitor PD98059 + MPC( MPD),and group of ERK inhibitor-PD98059( PD).The isolated rat hearts were treated on a Langendorff perfusion apparatus system. The coronary effluent was collected at 15 min of equilibration( baseline),5 and10 min of reperfusion for detection of the activity of LDH. Meanwhile,a water-filled balloon was inserted into the left ventricular for continuous LVDP measurement. The IS and AAR and IS/AAR ratios were observed by TTC. Western blot was used to examine the level of phosphorylated ERK in myocardium. Results As compared with the I/R group,MPC significantly decreased IS and IS/AAR ratio as well as LDH activities at 5 min and 10 min of reperfusion,but improved the LVDP at the end of reperfusion. Moreover,the phosphorylation level of ERK in myocardium was upregulated by MPC. However,ERK inhibitor PD98059 could block the protective effects of MPC,as indicated by the increased IS and IS/AAR ratio,elevated LDH activity at the reperfusion of 5 and 10 min,and the suppressed LVDP at the end of reperfusion. Furthermore,the MPC-induced phosphorylation of ERK was also reversed by PD98059. Conclusion Morphine preconditioning may confer cardio-protection against the global ischemia-reperfusion injury in rat hearts through enhancing the phosphorylation of ERK.