吗啡后处理对大鼠离体心脏缺血再灌注损伤的影响

目的 评价吗啡后处理对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠,体重180～200 g,应用Langendorff灌流装置,采用全心停灌45 min、再灌注60 min的方法制备大鼠离体心脏缺血再灌注模型.实验一:取模型制备成功的心脏32个,随机分为4组(n=8):Ⅰ组～Ⅳ组,Ⅰ组不予处理,Ⅱ组～Ⅳ组于再灌注即刻分别灌注含0.3、3.0和30 μmol/L吗啡的K-H液10 min,随后灌注正常K-H液50 min;实验二:根据实验一的结果,选择对离体心脏缺血再灌注损伤影响最强的吗啡浓度,另取模型制备成功的心脏32个,随机分为4组(n=8):Ⅰ组～Ⅳ组,Ⅰ组不予处理,Ⅱ组～Ⅳ组于再灌注即刻分别灌注含吗啡的K-H液5、10和20 min,随后灌注正常K-H液50 min;实验三:根据实验二的结果,选取对离体心脏缺血再灌注损伤影响最强的吗啡后处理方法.另取模型制备成功的心脏37个,随机分为5组:Ⅰ组(n=8)不予处理;Ⅱ组(n=8)、Ⅲ组～Ⅴ组(n=7)于再灌注即刻分别灌注含吗啡、10 μmol/L非选择性阿片受体阻断剂纳洛酮和吗啡、5 μmol/L选择性κ受体阻断剂nor-binahorphimine和吗啡、5 μmol/L选择性δ受体阻断剂naltrindole和吗啡的K-H液,各组均再灌注正常K-H液50 min.于再灌注60 min时测定心肌肌酸激酶同工酶(CK-MB)活性,计算心肌缺血危险区/梗塞区(IS/AAR).结果 根据实验一、二的结果于再灌注即刻灌注含3.0 μmol/L吗啡的K-H液10 min行后处理.实验三的结果:与Ⅰ组比较,Ⅱ组和Ⅴ组心肌IS/AAR和CK-MB活性降低,Ⅳ组心肌CK-MB活性降低(P<0.05或0.01),Ⅲ组以上指标差异无统计学意义(P>0.05);与Ⅱ组比较,Ⅲ组和Ⅳ组心肌IS/AAR和CK-MB活性升高(P<0.01),Ⅴ组上述指标差异无统计学意义(P>0.05).结论 吗啡后处理可减轻大鼠离体心脏缺血再灌注损伤,此作用可能与激活心肌κ受体有关.

Effects of morphine postconditioning on ischemia-reperfusion injury in isolated rat hearts

Objective To determine whether morphine postconditioning (MP) could protect the heart against ischemia reperfusion (I/R) injury and which specific type(s) of the opioid receptor is involved in the cardioprotective effect produced by hiP. Methods Male SD rots weighing 180-200 g were killed after intraperitoneal heparin 500 U/kg. The hearts were immediately removed and passively perfused in a Langendorff apparatus with K-H solution gassed with 95% O2-5% CO2. HR and left ventricular systolic pressure (LVSP) were measured from a fluid-filled latex balloon in the left ventricle. Global myocardial ischemia was induced by interrupting perfusion for 45 min followed by 60 min reperfusion. The experiment was performed in 3 parts. In Part Ⅰ 32 isolated rat hearts were randomly divided into 4 groups (n = 8 each): group Ⅰ control received no treatment; group Ⅱ ,Ⅲ,Ⅳ were first perfused with K-H solution containing morphine 0.3, 3.0 and 30 μmol/L respectively for 10 min immediately after the end of ischemia followed by 50 min normal K-H solution perfusion. In part Ⅱ,the concentration of morphine in K-H solution which provided the best cardio-protective effects was chosen according to the result of Part Ⅰ , 32 isolated rat hearts were randomly divided into 4 groups ( n = 8 each) : group Ⅰ received no treatment; gvoup Ⅱ,ⅢⅣ were first perfused with K-H solution containing morphine for 5, 10, 20 min respectively immediately after ischemia followed by 50 min peffusion with normal K-H solution. In part Ⅲ,the MP method which provided the best cardio-protective effects was chosen according to the result of Part Ⅱ , 37 isolated rat hearts were randomly divided into 5 groups: group Ⅰ control (n=8);group Ⅱ-Ⅴ were first perfused for 10 min with K-H solution containing morphine (Ⅱ,n = 8)/morphine + naloxone 10 μmol/L(Ⅲ, n = 7)/morphine + nor-binaltorphimine 5 μmol/L (specific κ receptor antagonist, n = 7)/morphine + nalu'indole 5 μmol/L (specific δ receptor antagonist, n = 7) followed by 50 min reperfusion with normal K-H solution. Myocardial CK-MB activity was measured and myocardial infarct size (IS/AAR) determined (by 2,3,5-triphenyl tetrazolium staining) at the end of 60 min reperfusion.Results The postconditioning with morphine 3.0 μmol/L perfusion for 10 min provided the best cardio-protective effects in terms of IS/AAR and myocardial release of CK-MB. Nuloxone completely abolished the cardio-protective effects of MP. Nor-binaltorphimine partly reversed the protective effect of MP, while naltrindole had no effects on MP. Conclusion MP protects the heart against I/R injury via activating κ receptor.