挥发性麻醉药对大鼠离体心脏缺血再灌注损伤的影响

目的： 研究挥发性麻醉药对大鼠离体心脏缺血再灌注损伤的影响。方法： SD大鼠136只，随机分为17组，每组8只。采用Langendorff离体大鼠心脏模型。按给药方式分为6大组：假手术组（含1亚组）：自然灌流85 min;对照组（含4亚组）：平衡15 min为1亚组，平衡后续灌15 min为1亚组，平衡续灌后缺血10 min为1亚组，平衡续灌缺血25 min后复灌30 min为1亚组;氟烷组（含3亚组）：平衡15 min后，灌注含1.5 MAC氟烷灌注液15 min为1亚组，平衡续灌含药液后缺血10 min为1亚组，平衡续灌缺血25 min复灌含1.5 MAC氟烷的灌注液30 min为1亚组;1.5 MAC的恩氟烷、异氟烷、七氟烷大组，各大组包括3亚组，处理同氟烷组。记录各组心脏在平衡15 min、给药后(或续灌15 min)、复灌30min的左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室发展压(LVDP)、左室压力升高或降低最大速率(±dp/dtmax)、心率（HR）、冠脉流量（CF）。实验结束后测定心肌超氧化物歧化酶（SOD）活性、心肌丙二醛（MDA）含量、高能磷酸盐（ATP）含量、Na＋-K＋-ATP酶、Ca2＋-ATP酶活性。结果： （1）恩氟烷、异氟烷、七氟烷组在给药后CF高于对照组（P<0.05）；各用药组在给药后LVDP、±dp/dtmax低于对照组（P<0.01）、而LVEDP高于对照组（P<0.05）；复灌30 min各用药组LVDP、±dp/dtmax高于对照组（P<0.01）。氟烷、异氟烷组在给药后和复灌30 min的HR低于对照组（P<0.05或P<0.01）。（2）各用药组在缺血前、缺血期和复灌30 min的心肌ATP含量高于及复灌30 min SOD活性高于对照组，MDA含量低于对照组（P<0.05或P<0.01）。（3）氟烷、恩氟烷、异氟烷组在缺血前Ca2＋-ATP酶活性低于对照组、各用药组在缺血期和复灌30 min此酶活性高于对照组（P<0.05或P<0.01）。（4）在复灌30min，氟烷组的Na＋-K＋-ATP酶活性高于对照组和其它3用药组（P<0.05或P<0.01）。结论： 挥发性麻醉药可抑制心肌收缩功能，对缺血再灌注心肌有保护作用。缺血再灌注后，能明显促进心肌功能与代谢的恢复，而且能提高CF、心肌Ca2＋-ATP酶及Na＋-K＋-ATP酶活性。     

二氮嗪后处理对离体大鼠心功能及线粒体心磷脂的影响

目的:建立离体大鼠心肌缺血/再灌注损伤模型,观察二氮嗪(diazoxide,D)后处理对缺血/再灌注损伤离体大鼠心功能及线粒体心磷脂的影响,并探讨ATP敏感性钾通道在二氮嗪后处理心肌保护中的作用。方法:采用Langendorff装置建立离体大鼠心肌缺血/再灌注损伤模型,将SD大鼠随机分为对照组(control)、缺血再灌注模型组(I/R)、二氮嗪后处理组(I/R+D)、5-羟葵酸拮抗二氮嗪后处理组(I/R+5-HD+D),每组8只,均先灌注平衡20 min。Control组:灌注平衡后续灌70 min;I/R组:缺血前灌注4℃ST.Thomas停跳液,全心缺血40 min,再灌30 min;I/R+D组:全心缺血40 min,缺血后给予含二氮嗪(50μmol/L)的K-H液灌注5 min后,再灌25 min;I/R+5-HD+D组:二氮嗪后处理前给予含5-羟葵酸(100μmol/L)的K-H液灌注5 min,再灌20 min。观察各组续(再)灌注末心率、冠脉流出液量、心功能、心肌酶学及心肌线粒体心磷脂的变化。结果:各组续(再)灌注末比较,I/R组较control组及I/R+D组心率减慢、冠脉流出液量降低,心功能明显受损,心肌酶增加,心磷酯含量减少,但与I/R+5-HD+D无明显差异。结论:二氮嗪后处理通过增加线粒体心磷脂含量,减少心肌酶的释放,改善心脏功能,减轻心肌的再灌注损伤,产生心肌保护作用。5-羟葵酸能够完全阻断二氮嗪的心肌保护作用。     

NO参与缺血预处理对大鼠骨骼肌缺血再灌注损伤的保护作用

目的研究缺血预处理(IPC)对大鼠骨骼肌缺血再灌注损伤的保护作用及一氧化氮(NO)是否参与此保护作用。方法采用Wistar雌性大鼠,在左后肢跟部止血,同时使用血流监测仪测股四头肌的血流量,调整止血带的松紧程度,使血流量控制在上止血带前的30%。30只大鼠随机分成3组,分别为缺血再灌注组(n=10)、缺血预处理组(n=10)、缺血预处理+NAME组(n=10)。应用尼克酰胺腺嘌呤二核苷酸黄递酶2+2+(NADH)染色,检测股四头肌各型肌纤维横截面积,钙-腺苷三磷酸酶(Ca-ATPase)染色,观察细胞膜CaATPase分布。透射电镜观测肌细胞的超微结构变化。结果缺血再灌注组出现明显肌纤维破裂溶解,许多白细胞浸润,电镜下线粒体中含有大量空泡变性、肌纤维断裂、溶解和"Z线"排列整齐膜脂质过氧化物的增加。与缺血再灌注组相比,缺血预处理组显示了轻微的损害,正常的纤维和血管变形少,股四头肌各型肌纤维横2+截面积降低,细胞膜Ca-ATPase数量增加。缺血预处理+NAME组与缺血再灌注组相比没有明显改变。结论缺血预处理对大鼠骨骼肌缺血再灌注损伤有明显保护作用,NO参与这一保护作用。     

非创伤性预处理在离体心脏抗再灌注损伤中作用机制的探讨

目的:观察非创伤性肢体缺血预处理对大鼠离体再灌注心肌是否有保护作用。方法:实验采用体重(250±30)gSD雄性大鼠25只随机分成3组,在Langendorff装置上对大鼠离体心脏进行灌流。对照组(C,n=8):在灌注全程均用富氧K-H液(充以95%O₂+5%CO₂),在恒压(8.33kPa)、恒温(37℃)条件下灌注;缺氧/复氧组(A,n=8):预灌15min后,灌注心脏先全心缺血缺氧15min,随后15min复氧再灌注(37℃);非创伤性肢体缺血预处理组(N-WIP,n=9):先将大鼠双后肢捆绑5min,松开5min,反复4次后,随后的方法同R组。在相应时点分别测定冠脉流出液和心肌匀浆中超氧化物歧化酶(SOD)活性,Ca²⁺-Mg²⁺-ATP酶活性和丙二醛(MDA)含量,同时记录心肌细胞的单相动作电位(MAP)和心肌收缩张力曲线。结果:非创伤性肢体缺血预处理能使再灌注心律失常发生率显著低于A组;心肌组织中MDA含量显著低于A组,心肌组织中SOD活性显著高于A组,心肌细胞的膜电位、Ca²⁺-Mg²⁺-ATP酶活性及肌张力较稳定。结论:非创伤性肢体缺血预处理对大鼠离体再灌注心肌有明显的保护作用,可能是通过增强心肌的抗氧化能力、稳定心肌Ca²⁺-Mg²⁺-ATP酶活性和膜相结构等途径,提高心肌细胞对再灌注损伤的抵抗力。     

甘氨酰谷氨酰胺在大鼠离体心脏缺血/再灌注损伤中的保护作用研究

目的： 研究甘氨酰谷氨酰胺对缺血再灌注大鼠离体心脏的保护作用。方法：应用Langendorff离体心脏灌注系统建立心肌缺血再灌注模型。30只SD雄性大鼠随机分为正常对照组(control)、甘氨酰谷氨酰胺对照组(Gly-Gln)、缺血再灌注组(I/R)、缺血/再灌注+甘氨酰谷氨酰胺组(I/R+ Gly-Gln)。I/R组及I/R+ Gly-Gln组分别灌注30 min后,全心停灌20 min,再灌注40 min,I/R+ Gly-Gln组于再灌注时在灌流液中加入Gly-Gln;正常对照组连续灌流90 min,Gly-Gln对照组灌流液中加入Gly-Gln。记录各组灌注时,左室舒张末压(LVEDP)、左室发展压(LVDP)、左室压力最大变化速率(±dp/dtmax)、心率(HR)及心肌细胞单相动作电位(MAP);同时在相应的时点分别测定冠脉流出液中的乳酸脱氢酶（LDH)、肌酸激酶(CK)活性。结果：离体大鼠心脏缺血20min,再灌注40 min,导致严重的心功能抑制,表现为LVEDP升高,LVDP、±dp/dtmax降低;再灌注液中加入Gly-Gln后,LVEDP降低,LVDP、±dp/dtmax明显升高（P<0.01)。I/R+ Gly-Gln组冠脉流出液中LDH、CK活性明显低于I/R组(均P<0.01)。结论： Gly-Gln能有效减轻缺血再灌注引起的左室功能下降,减少心肌细胞LDH、CK的释出,表明Gly-Gln对缺血再灌注损伤的大鼠离体心脏具有保护作用。     

11,12-EET和缺血预处置对在体大鼠正常及再灌注心肌磷酸化ERK和p38MAPK表达的影响

目的:观察11,12-环氧二十碳三烯酸(11,12-EET)和缺血预处置对大鼠再灌注心肌组织磷酸化ERK1/ERK2和p38 MAPK表达的影响,了解大鼠心肌磷酸化ERK1/ERK2和p38 MAPK表达与预处置有否关系。方法: 使用雄性Wistar大鼠,通过结扎(60 min)和松开(30 min)冠状动脉左前降支,复制缺血/再灌注模型;采用缺血5 min,再灌注5 min两次造成缺血预处置。大鼠经手术并静脉给予6.24×10^-8mol/L 11,12-EET,稳定20 min,结扎冠脉复制缺血/再灌注模型。实验分5组:①正常组(norm);②假手术组(sham);③缺血再灌注组(I/R);④短阵缺血预处置组(SI+I/R);⑤11,12-EET预处置缺血/再灌注组(EET+I/R)。采用Western blot法测定心肌细胞外调节的蛋白激酶(ERK1/2)和p38 MAPK的表达程度,并观察再灌注过程中心功能的变化。结果: 再灌注30 min时,I/R组+dp/dt_max%、-dp/dt_max%和LVDP均显著低于sham组、SI+I/R组和EET+I/R组(P＜0.05);而I/R组大鼠心肌ERK1/2磷酸化表达明显高于sham组(P＜0.05),明显低于SI+I/R组和EET+I/R组(P＜0.05);I/R组大鼠心肌p38 MAPK磷酸化表达I/R组显著高于sham组、norm组、SI+I/R及EET+I/R组(P＜0.05)。结论:6.24×10^-8 11,12-EET mol/L具有保护心功能的作用,这种保护作用可能与大量激活磷酸化ERK1/2和抑制p38 MAPK有关。     

氟烷和七氟醚对缺血心肌功能和代谢及Ca2+-ATP酶活性的影响

目的: 研究氟烷、七氟醚(1.5MAC)对缺血心肌的影响。方法: 应用离体大鼠心脏Langendorff逆行灌注模型研究氟烷、七氟醚对心肌缺血前心率(HR)、左室舒张末期压力(LVEDP)、左室发展压(LVDP)、左室压力升高速率(+dp/dt)、左室压力下降速率(-dp/dt)和冠脉流量(CF)的影响,测定缺血前、缺血10min、缺血25min3个不同时间的心肌ATP含量、Ca²⁺-ATP酶活性,同时记录缺血间期左室内压的变化情况。结果: 七氟醚显著增加正常离体心脏的CF,氟烷、七氟醚均不同程度地抑制心肌收缩功能和Ca²⁺-ATP酶活性,能够增加正常心肌的能量贮备。缺血10min时,二药能够减缓心肌ATP含量及Ca²⁺-ATP酶活性的下降,氟烷的作用比较明显。缺血间期,氟烷明显推迟缺血性挛缩的起始时间,降低挛缩幅度。结论: 氟烷的抗缺血损伤作用优于七氟醚,延缓缺血期心肌ATP含量及Ca²⁺-ATP酶活性的下降可能是氟烷抗缺血损伤作用的重要机制之一。     

缺血预处理前加用腺苷对未成熟兔心肌再灌注损伤的影响

目的和方法:建立3-4周龄幼兔离体心脏左心作功模型,心脏缺血期间均间断灌注心脏停搏液,研究缺血预处理前加用腺苷对未成熟兔再灌注心肌的保护作用并探讨其机制。结果:再灌注期,缺血预处理前加用腺苷的心脏的左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室内压上升最大速率(+dp/dt_max)和左室内压下降最大速率(-dp/dt_max)恢复最佳,肌酸激酶(CK)漏出率低,心肌组织丙二醛(MDA)含量低、超氧化物歧化酶(SOD)活性高,心肌组织三磷酸腺苷和二磷酸腺苷(ATP+ADP)含量高;心肌含水量(MWC)低。结论:缺血预处理前加用腺苷能强化缺血预处理对未成熟兔再灌注心肌的保护作用。     

Effects of volatile anesthetic preconditioning on expression of NFκB-regulated genes in aged rat myocardium

Volatile anesthetic preconditioning has been shown to be a potent way to provide myocardium protection against ischemia/reperfusion (I/R) injury; however, this cardioprotection is lost in senescent animal models and elderly patients. NFκB-regulated genes have been linked to myocardial I/R injury and anesthetic preconditioning. Here, we investigated NFκB activation related to anesthetic preconditioning in aging rat myocardium. Isolated, Langendorff perfused rat hearts from Fischer 344 male rats, 24 months old, were randomly assigned to one of the three groups. The hearts of the control group were perfused with physiologic solution without any intervention. The hearts in the I/R group were subjected to 25 minutes ischemia and followed by 60 minutes reperfusion. The hearts in the treatment group were subjected to 10 minutes 2.5% sevoflurane, followed by 20 minutes washout and by 25 minutes ischemia and 60 minutes of reperfusion, respectively. Left ventricular developed pressure (LVDP) and left ventricular enddiastolic pressure (LVEDP) were measured. Western blot analysis was used to measure inhibitor of κB (IκB) and antiapoptotic genes: A1, ILP, c-IAP-2, Bcl-2, caspase 8 and caspase 9. Ischemia and reperfusion significantly decreased LVDP and increased LVEDP in aged rat hearts. Anesthetic preconditioning with sevoflurane did not change the effects I/R on LVDP and LVEDP, despite the fact that after treatment with anesthetic preconditioning, the levels of IκB, A1, ILP, caspase 8 and caspase 9 were significantly different compared to those of the control hearts. In conclusion, anesthetic preconditioning with sevoflurane does not improve myocardial systolic and diastolic functions. Our results suggest that the activation of NFκB regulated genes is different in the senescent myocardium and could account for loss of cardioprotection with aging.     

银杏达莫注射液抑制大鼠离体心脏缺血/再灌注损伤的机制研究

 目的：观察银杏达莫注射液预处理对大鼠离体心脏缺血/再灌注损伤的影响,并探讨其可能的作用机制。方法：SD雄性大鼠40只随机分成5组（n=8）：正常对照（NC）组、缺血/再灌注（I/R）组、缺血预处理（IPC+I/R）组、银杏达莫注射液预处理（GD+I/R）组和银杏达莫+氯化镧预处理（GD+LaCl3+I/R）组。观察各组相同时点（预灌30 min稳定点,缺血30 min,再灌5 min、30 min、60 min）的心功能指标,包括心率(HR)、左室收缩压(LVSP)和室内压变化速率（±dp/dtmax）,同时收集各时点冠脉流出液,检测其中乳酸脱氢酶（LDH）和肌酸激酶（CK）活性。实验结束后检测心肌线粒体Ca2+浓度和α-酮戊二酸脱氢酶（α-OGDH）含量。结果：与I/R组比较,IPC+I/R组和GD+I/R组在心脏再灌注期各项心功能指标均得到改善（P<0.05）;心肌LDH和CK的释放量降低（P<0.01）;线粒体内Ca2+超载降低（P<0.01）,且线粒体内α-OGDH含量升高（P<0.05）;而GD+I/R组中银杏达莫对心肌的保护作用被LaCl3抑制（P<0.05）。结论：银杏达莫可能通过抑制钙超载、增强线粒体酶活性以稳定线粒体能量代谢,从而缓解缺血/再灌注诱导的心肌细胞损伤。     

吡那地尔后处理大鼠缺血再灌注损伤心肌线粒体的蛋白质组学研究

 目的: 运用蛋白质组学研究方法探讨吡那地尔后处理对缺血再灌注损伤大鼠心肌的保护作用。方法: 建立Langendorff大鼠离体心脏缺血再灌注损伤模型,随机分为吡那地尔后处理组(Pina组)和缺血再灌注损伤组(I/R组),每组9只。提取心肌线粒体蛋白质行双向凝胶电泳,应用质谱鉴定差异大于2倍的蛋白质点。结果: Pina组与I/R组比较,共发现7个差异蛋白质:Pina组NADH脱氢酶1α亚复合体10亚基(NDUFA10)﹑NADH脱氢酶铁硫蛋白2(NDUFS2)和NADH脱氢酶黄素蛋白2(NDUFV2)表达低于I/R组;Pina组异柠檬酸脱氢酶α亚基(IDHA)和Δ^3,5-Δ^2,4-二烯酰辅酶A异构酶(ECH1)表达高于I/R组;另有2个蛋白质点均被鉴定为ATP合酶δ亚基,一个蛋白质点表达升高,而另一个表达降低。结论:吡那地尔后处理可能抑制了复合体Ⅰ的亚基(NDUFA10﹑NDUFS2和NDUFV2)代偿性增加,但促进了IDHA和ECH1表达并引发了ATP合酶δ亚基发生磷酸化,这些改变可能均与吡那地尔后处理保护心肌的作用有关。     

Attenuation of conduction delay by ischemic preconditioning reduces ischemia-induced ventricular arrhythmias

Ischemic preconditioning has been acknowledged as a powerful method of decreasing ischemic injury. However, the antiarrhythmic mechanism of ischemic preconditioning during ischemia is unclear. We studied the effects of ischemic preconditioning on arrhythmias and cardiac electrophysiology during ischemia in Langendorff rat hearts (n = 44). In the non-preconditioned group (PC(-); n = 24), the hearts underwent 5-min zero-flow global ischemia without any prior ischemic preconditioning. In the preconditioned group (PC(+); n = 20), the hearts were preconditioned by three cycles of 3-min zero-flow global ischemia and 5-min reperfusion before undergoing 5-min global ischemia. Ischemic preconditioning reduced the incidence of ischemia-induced arrhythmias (PC(-); 38.9%, PC(+): 8.3%, p < 0.05), shortened monophasic action potential duration (MAPD, P < 0.05), attenuated conduction delay (conduction time; PC(-): 234.2%, PC(+): 173.4%, P < 0.05) and increased the ventricular fibrillation threshold. Although the shortening of MAPD in PC(-) hearts was not influenced by the presence or absence of arrhythmias, conduction time prolongation at 3-min was more obvious in PC(-) hearts with arrhythmia than in PC(-) hearts without arrhythmia (PC(-) with arrhythmia: 220.2%, PC(-) without arrhythmia: 190.7%, P < 0.05). We concluded that ischemic preconditioning could protect the rat hearts from ischemia-induced arrhythmias and postulated that attenuation of conduction delay during ischemia might be an important factor in the antiarrhythmic action of ischemic preconditioning.     

Relation between ischemic preconditioning and the duration of sustained ischemia.

It has been reported that repetitive brief periods of ischemia and reperfusion (ischemic preconditioning, IP) cause a significant reduction in the extent of myocardial necrosis or in the incidence of reperfusion arrhythmias in rat heart. However, recent reports have stated that IP effect is diminished or lost in the canine or bovine heart if ischemia (mostly regional) is sustained for 40 min or longer. The main objective of this study is to assess whether IP provides myocardial protection in prolonged sustained ischemia under the condition of global ischemia in isolated rabbit heart. The hearts were subjected to 10-60 min sustained ischemia (SI) followed by 60 min reperfusion with (IP heart) or without IP (ISCH heart). IP was induced by 4 cycles of 5 min global ischemia and 5 min reperfusion. Left ventricular function (LVF), extent of infarction (EI) and ultrastructural changes were examined. As a whole, the LVF began to recover on reperfusion but there was no significant difference in the functional parameters. However, extracellular Ca2+ concentration was lower in the ISCH hearts (p < 0.05) and the EI was significantly different between the hearts which had received 60 min SI (67% in the ISCH versus 32% in the IP heart, p < 0.01). Ultrastructural changes were homogeneous in the ISCH hearts and became irreversible in accordance with increase of the duration of ischemia, while these changes were heterogeneous and restricted in the IP heart. These results suggest that IP does not attenuate the postischemic dysfunction in prolonged ischemia but it can provide an infarct size-limiting effect and delay ultrastructural changes. This cardioprotective effect may be related to calcium homeostasis.     

三氧化二砷预处理在离体心肌缺血-再灌注损伤中保护作用的初探

目的研究三氧化二砷（As2O3）预处理在心肌缺血-再灌注损伤中的保护作用,并初步探讨其机制。方法分别采用低中高三个剂量As2O3预处理大鼠,利用离体大鼠心脏Langendorff灌流模型,观察心功能、心肌梗死面积,SOD,MDA等指标的变化。结果As2O3预处理各组的左室舒张末压（LVDEP）、左室发展压（LVDP）、最大左室收缩速率（＋dP／dtmax）和最大左室舒张速率（-dP／dtmax）等各项心功能指标均得到明显改善,SOD活性显著升高,MDA含量大幅度下降。结论As2O3,预处理可对抗心肌缺血一再灌注性损伤,其作用可能与抗氧化应激有关。     

Troxerutin Preconditioning and Ischemic Postconditioning Modulate Inflammatory Response after Myocardial Ischemia/Reperfusion Injury in Rat Model

Protective effects of ischemic postconditioning in myocardial ischemia/reperfusion (I/R) injury have been ever demonstrated, but the exact mechanisms remain unclear. Because of their multiplex activities, using natural pharmaceuticals seems to be clinically interesting. The aim of present study was to investigate the effects of troxerutin preconditioning and ischemic postconditioning on inflammatory responses after myocardial I/R injury in a rat model. Twenty-four Wistar rats were divided into four groups as the control, troxerutin receiving (TXR), postconditioning receiving (PostC), and combined therapy (TXR + PostC). Rats’ isolated hearts underwent 30-min LAD regional ischemia followed by 45-min reperfusion. Troxerutin was orally administered for a month before I/R. Ischemic PostC was applied by alternative three cycles of 30-s R/I at the onset of reperfusion. The coronary effluent and ischemic left ventricular samples were used to determine the activities of creatine kinase (CK), intercellular adhesion molecule-1 (ICAM-1), interlukin-1beta (IL-1β), tumor-necrosis factor (TNF-α), and also histopathological studies. Pretreatment of rats with troxerutin significantly reduced myocardial inflammatory cytokines TNF-α and IL-1β levels and ICAM-1 activity after I/R insult compared to those of control I/R hearts (P?<?0.05). Application of PostC showed similar impacts on those parameters. In fact, anti-inflammatory mechanisms of both treatments were associated with their protective effects against myocardial damages causing from I/R injury. Pretreatment with troxerutin as well as postconditioning can induce cardioprotection through prevention of the cell-cell interaction and release of inflammatory mediators, minimizing I/R pathological changes in myocardial cells. These two treatments may share same mechanisms in their actions since they showed no significant additive effects.     

基于压力相平面推导的τ和K在评价离体缺血/再灌注大鼠心脏左心室舒张功能中的作用

目的:应用分析和比较基于压力相平面(PPP)推导的心室等容舒张期时间常数)(和室腔僵硬度常数(K)在离体大鼠心脏缺血/再灌注过程中的变化,探讨其在评价左心室舒张功能异常中的价值。方法:采用SD大鼠心肌不同时程缺血/再灌注模型,分别计算出LVEDP、-(dp/dt)max、和K。同时,检测冠脉流出液中的乳酸脱氢酶(LDH),并进行心肌电镜观察。结果:在再灌注过程中,在各缺血组均明显高于空白对照组(P0.05),K在各缺血组均明显低于空白对照组(P0.05);而且,随着缺血时间延长,更高,K更低(P0.05)。除了缺血15min组,其余各组LDH含量在再灌注10min和20min时均高于空白对照组(P0.05);缺血45min组和缺血60min组LDH含量在再灌注10min和20min时均高于缺血30min组(P0.05)。随着缺血时间延长,心肌超微结构发生异常改变。结论:基于PPP推导的和K可以作为定量评价离体大鼠心脏缺血/再灌注过程中的左心室舒张功能的指标,还可以反映缺血/再灌注损伤的严重程度。     

血红素氧化酶-1在离体大鼠心肌缺血预处理中的作用

目的：观察缺血预处理对离体大鼠心肌缺血再灌注后心功能、乳酸脱氢酶（LDH）活性和丙二醛（MDA）含量及血红素氧化酶-1活性的影响。方法：应用Langendorff离体大鼠等容收缩灌流模型行离体大鼠心脏灌流。缺血预处理方案为停灌5 min后再灌5 min反复3次,持续缺血再灌方案为停灌40 min后再灌20 min,监测正常对照组、缺血再灌组（IR）和缺血预处理组（IPC）心功能指标的同时,测定冠脉流出液LDH活性、心肌MDA含量和HO-1活性变化。结果：IPC组再灌20 min时的心功能恢复率显著高于IR组（P<0.01）,心肌血红素氧化酶-1活性也明显高于IR组（P<0.05）,而LDH活性及MDA含量显著少于IR组（均为P<0.01）。结论：血红素氧化酶-1活性增高可能与缺血预处理对大鼠缺血再灌心肌的保护作用有关。     

亚甲蓝减轻大鼠离体心脏缺血/再灌注引起的线粒体损伤

目的:探讨亚甲蓝(methylene blue,MB)对大鼠离体心脏缺血/再灌注(ischemia/reperfusion,I/R)线粒体损伤的作用。方法:将Spragure-Dawley大鼠随机分为对照组(control组)、I/R模型组和MB治疗组(I/R+MB组),建立Langendorff离体心脏灌注模型(n=6)。手术前2 h,MB组大鼠按2 mg/kg腹腔注射MB。对照组持续灌注K-H液110 min,I/R组与I/R+MB组平衡灌注20 min后停灌30 min,再灌注60 min。实时记录心率(HR)、左室发展压(LVDP)、左室最大压力变化速率(±dp/dt_(max))和左室舒张末压(LVEDP)。测定冠脉流出液中肌酸激酶MB同工酶(CK-MB)和乳酸脱氢酶(LDH)活性。测定心肌组织中活性氧簇(ROS)、丙二醛(MDA)和三磷酸腺苷(ATP)含量以及超氧化物歧化酶(SOD)活性。苏木精-伊红染色观察组织病理学变化。分离心肌组织线粒体,测定线粒体肿胀程度和线粒体膜电位(MMP)。结果:与对照组相比,I/R组的心功能恶化,冠脉流出液中的CK-MB和LDH活性升高,心肌组织中的ROS和MDA增加,SOD活性降低,ATP减少,线粒体肿胀程度升高,MMP下降(P0.05);与I/R组相比,I/R+MB组的心功能改善,CK-MB和LDH的释放减少,组织中的ROS和MDA减少,SOD活性和ATP含量升高,线粒体肿胀程度降低,MMP升高(P0.05)。结论:MB通过减轻线粒体损伤对大鼠离体I/R心脏发挥保护作用。     

Involvement of Ca(2+) in antiarrhythmic effect of ischemic preconditioning in isolated rat heart

We investigated the relationship between the effects of ischemic preconditioning (IPC) and Ca(2+) preconditioning (CPC) on reperfusion-induced arrhythmias. In the control group (noPC), Langendorff-perfused rat hearts were subjected to 5-min zero-flow global ischemia (I) followed by 15-min reperfusion (I/R). In ischemic preconditioning groups (IPC), the hearts were subjected to three cycles of 3-min global ischemia and 5-min reperfusion. In the CPC group, the hearts were exposed to three cycles of 3-min perfusion of higher Ca(2+) (2.3 mmol/l Ca(2+)) followed by 5-min perfusion of normal 1.3 mmol/l Ca(2+), and the hearts were then subjected to I/R. Verapamil was administered in several hearts of the IPC group (VR+IPC). Ventricular arrhythmias upon reperfusion were less frequently seen in the IPC and CPC groups than in the noPC and VR+IPC groups. IPC and CPC could attenuate conduction delay and enhance shortening of the monophasic action potential duration during ischemia. The ventricular fibrillation threshold measured at 1-min reperfusion was significantly higher in the IPC and CPC groups than in the noPC and VR+IPC groups. Verapamil completely abolished the salutary effects of IPC. These results demonstrate that Ca(2+) plays an important role in the antiarrhythmic effect of IPC during reperfusion.     

依达拉奉对离体大鼠心肌缺血再灌注损伤的保护作用

目的:探讨依达拉奉(ED)预先给药对大鼠离体心肌缺血再灌注(I/R)损伤的作用及其机制。方法:制作Langendorff主动脉逆行灌注心脏I/R模型。24只雄性大鼠随机分为三组(n均=8):对照组(C组)、I/R组、ED组。观察各组大鼠I/R后心功能指标:左室收缩峰压(LVSP)、左室压上升最大速率(+dp/dtmax)、左室压下降最大速率(-dp/dtmax)、冠脉流量(CF)、心肌细胞乳酸脱氢酶(LDH)及肌酸激酶同工酶(CK-MB)活性、心肌组织丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性。结果:与基础值和C组比较,I/R组再灌注时各时点的CF、LVSP、+dp/dtmax、-dp/dtmax降低(P<0.05);与I/R组比较,ED组再灌各时点的CF、LVSP、+dp/dtmax、-dp/dtmax增高(P<0.05);ED组心肌SOD活性明显高于I/R组(P<0.05),LDH及CK-MB活性、MDA含量低于I/R组(P<0.05)。结论:ED对I/R心肌有保护作用,能促进心功能恢复。其机制与清除自由基和减轻氧化应激有关。