吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38MAPK表达的影响

目的 评价吡那地尔超极化停搏对大鼠离体心脏缺血再灌注时p38丝裂原活化蛋白激酶(p38MAPK)表达的影响.方法 成年雄性SD大鼠48只,体重250～300 g,采用随机数字表法,将大鼠随机分为6组(n=8):自然停搏组(A组)、St.Thomas组(B组)、吡那地尔超极化停搏组(C组)、5-羟葵酸(5-HD)组(D组)、HMR-1098组(E组)和5-HD+HMR-1098组(F组).采用Langendorff离体心脏灌注模型,K-H液平衡灌注15 min后,A组阻断主动脉,不予停搏液灌注,使其自然停搏；B组灌注St.Thomas停搏液；C组灌注吡那地尔超极化停搏液；D组、E组和F组K-H液平衡灌注10 min后,分别灌注含5-HD、HMR-1098、5-HD+ HMR-1098的K-H液5min,再灌注吡那地尔超级化停搏液.心脏停跳缺血60 min后,K-H液再灌注30 min.于平衡灌注15 min和再灌注20 min时记录冠脉流量(CF)、心率(HR)、左室发展压(LVDP)、左室收缩压(LVSP)和左室压力瞬时最大变化率(dp/dtmax)；于再灌注30 min时取心肌组织,采用Western blot法测定心肌磷酸化p38MAPK和非磷酸化p38MAPK的表达.结果 与C组相比,A组、B组、D组、E组和F组再灌注20min时CF、HR、LVSP、LVDP及dp/dt/dymax降低,再灌注30 min时磷酸化p38MAPK表达下调,非磷酸化p38MAPK表达上调(P＜0.05)；与E组相比,D组和F组再灌注20 min时CF、HR、LVSP、LVDP及dp/dtmax降低,再灌注30 min时磷酸化p38MAPK表达下调,非磷酸化p38MAPK表达上调(P＜0.05).结论 吡那地尔超极化停搏可改善大鼠离体缺血再灌注心脏功能,其机制与上调磷酸化p38MAPK表达,下调非磷酸化p38MAPK表达有关,而这种调控作用与线粒体ATP敏感性钾通道关系更密切.

Effect of pinacidil hyperpolarized arrest on p38 mitogen-activited protein kinase expression during myocardial ischemia-reperfusion in isolated rat hearts

Objective To investigate the effect ofpinacidil hyperpolarizaed arrest on p38 mitogen-activited protein kinase (p38MAPK) during myocardial ischemia-reperfusion (I/R) in isolated rat hearts.Methods Fortyeight male SD rats weighting 250-300 g were randomly divided into 6 groups( n =8 each): natural arrest group (group A) ; St.Thomas group (group B) ; pinacidil hyperpolarization arrest group (group C) ;5-hydroxydecanoate (5-HD) group (group D);HMR-1098 group(group E) and 5-HD + HMR-1098 group(group F).Langendorff reperfusion model was established and K-H solution was retrogradely perfused for 15 min.In group A the hearts were arrested naturally afar perfusion was stopped; in group B St.Thomas solution was perfused; in group C pinacidil hyperpolarization solution was perfused; in the other three groups,K-H solution was perfused to isolated rat hearts for 10 min followed by 5 min 5-HD (group D) or HMR-1098(group E) or 5-HD and HMR-1098(group F) perfusion,then hyperpolarization arrest solution was given in each group.Each hearts suffered 60 min ischemia after arrest followed by 30 min K-H solution reperfusion.Coronary flow(CF),HR,left ventricular developed pressure( LVDP),left ventricular systolic pressure(LVSP) and the maximum rate of pressure rise (dp/dtmax) were measured at the end of 15 min K-H solution perfusion and at 20 min of reperfusion.Myocardial phosphatic and nonphosphatic p38MAPK expression was determined by Western blot at 30 min of reperfusion.Results Compared with group C,CF,HR,LVDP,LVSP and dp/dtmax were significantly decreased at 20 min of reperfusion and phosphatic p38MAPK expression was down-regulated,non-phosphatic p38MAPK expression was up-regulated at 30 min of reperfusion in groups A,B,D,E and F (P ＜ 0.05).Compared with group E,CF,HR,LVDP,LVSP and dp/ dtmax were significantly decreased at 20 min of reperfusion and phosphatic p38MAPK expression was down-regulated,non-phosphatic p38MAPK expression was up-regulated at 30 min of reperfusion in groups D and F ( P ＜0.05).Conclusion Hyperpolarized arrest induced by pinacidil can improve cardiac function following myocardial I/R injury by up-regulating phosphatic p38MAPK expression,down-regulating non-phosphatic p38 MAPK expression and mitochondrial potassium channel is more important than membranous one during the regulation of phosphatic p38MAPK expression.