依达拉奉对大鼠心肌再灌注抗凋亡作用的机制

目的：观察大鼠心肌缺血再灌注时依达拉奉抗凋亡作用的机制。方法：采用体外结扎大鼠左前降支制备大鼠心肌缺血再灌注模型。将Wistar大鼠随机分为对照组、缺血再灌注组、依达拉奉组（再灌注即刻经尾静脉注射依达拉奉3mg／kg）。分别用TUNEL染色法及免疫组化法检测心肌细胞凋亡、心肌凋亡蛋白Bcl-2、Bax的表达。结果：（1）凋亡检测结果示,对照组无细胞凋亡,依达拉奉组较缺血再灌注组凋亡细胞数明品减少[（13．11±1．58）比（24．33±1．38）,P〈0．01];（2）免疫组化结果示,依达拉奉组与缺血再灌注组Bcl-2、Bax蛋白表达均明显高于对照组（P〈0．01）;依达拉奉组较缺血再灌注组Bcl-2蛋白表达明显升高[（0．2300±0．0218）比（0．0924±0．0152）],而Bax蛋白表达明显降低[（0．0249±0．0042）比（O．1312±0．0173）],P均〈0．01;缺血再灌注组Bcl-2／Bax比值较对照组明显降低[（0．6906±0．0035）比（1．1632±0．0212）],依达拉奉组Bcl-2／Bax比值（7．4752±0．5573）较缺血再灌注组和对照组明显升高（P〈0．01）。结论：依达拉奉能够减少心肌细胞凋亡,心肌细胞凋亡的减轻与下调Bax蛋白表达,上调Bcl-2蛋白表达以及Bcl-2／Bax比值有关。     

钙敏感受体参与心肌缺血再灌注损伤诱发细胞凋亡的机制

目的 探讨钙敏感受体（CaSR）参与心肌缺血再灌注损伤诱发细胞凋亡的机制。方法 采用离体大鼠心肌缺血再灌注损伤模型。实验分5组：对照组灌注2h；缺血组单纯缺血40min；缺血再灌注组缺血40min再灌注2h；激动剂组同缺血再灌注组，在再灌注液中加入氯化钆（GdCl3）；阻断剂组同缺血再灌注组，在再灌注液中加入氯化镍（NiCl2）和氯化镉（CdCl2）。利用光镜观察各组心肌细胞凋亡情况；检测各组乳酸脱氢酶（LDH）活力和丙二醛（MDA）水平变化；Western Blot分析各组心肌组织中CaSR、Bcl-2和Caspase-3的表达。结果 缺血再灌注和激动剂组细胞凋亡指数、LDH活力和MDA水平明显高于对照组；同时CaSR、细胞浆中的Caspase-3表达也明显高于对照组．反之，Bcl-2表达低于对照组。结论 CaSR参与缺血再灌注损伤所诱发的细胞凋亡。     

竹叶总黄酮抗大鼠心肌细胞凋亡作用的研究

目的研究竹叶总黄酮对大鼠心肌缺血再灌注时心肌细胞凋亡的影响。方法用在体左冠状动脉前降支穿线结扎法制备心肌缺血再灌注模型。将60只SD大鼠分为6组：假手术组，缺血再灌注组，竹叶总黄酮高、中、低剂量组，阳性对照组每组10只。缺血30min，再灌注240min。采用缺口末端标记法（TUNEL）以及免疫组化法，检测心肌细胞凋亡千分率、Bcl-2、Bax、Cyt-c和caspase-3基因蛋白表达。结果TUNEL实验表明竹叶总黄酮能明显降低心肌组织凋亡的发生；与假手术组比较，缺血再灌注组Bax、Cyt-c、Bcl-2和caspase-3阳性表达增强（P〈0．01）；与缺血再灌注组比较，竹叶总黄酮明显抑制了Bax、Cyt-c和caspase-3表达但没有抑制Bcl-2表达。结论竹叶总黄酮对心肌缺血再灌注损伤具有保护作用。     

牛磺酸对大鼠心肌缺血再灌注损伤细胞凋亡的影响

目的观察牛磺酸对大鼠心肌缺血再灌注损伤后细胞凋亡的影响。方法实验大鼠40只,随机分为5组：假手术组（8只）,再灌注模型组（8只）,牛磺酸低、中、高剂量（30mg／kg、100mg／kg、300mg／kg）组（各8只）。再灌注后观察各组血清SOD、LDH、MDA含量,TUNEL法检测心肌细胞凋亡。结果①牛磺酸对大鼠心肌缺血再灌注后血清SOD、LDH、MDA含量的影响：与假手术组比较,其余各组大鼠血清SOD活性明显降低,LDH、MDA含量明显增高（P〈0．05,P〈0．01）;与模型组比较,牛磺酸中、高剂量组大鼠血清SOD活性明显升高（P〈0．01）,LDH、MDA含量明显降低（P〈0．05,P〈0．01）。②牛磺酸对大鼠心肌缺血再灌注（I／R）损伤后细胞凋亡的影响：I／R后心肌细胞凋亡指数（AI）为（45．6±4．6）,明显高于假手术组的（8．50±1．13）（P〈0．01）,牛磺酸低、中、高组分别为（37．03±3．52）、（30．32±8．23）和（25．62±6．12）,均明显低于I／R（P〈0．01）。结论牛磺酸可降低再灌注损伤大鼠氧自由基值,抑制心肌细胞凋亡。     

肾脏缺血后处理对兔急性缺血再灌注心肌细胞凋亡和Bcl-2、Bax蛋白表达的影响

目的研究肾脏缺血后处理对兔急性缺血再灌注心肌细胞凋亡的影响,并探讨其保护机制。方法24只新西兰大白兔随机分为3组,每组8只。（1）缺血再灌注组（IR组）：结扎左冠状动脉前降支1h,再灌注6h。（2）肾脏缺血后处理组（RI-Post组）：操作同IR组,在再灌注即刻用动脉血管夹反复夹闭左侧肾动脉（阻断30S,再通30S,重复3次）,再灌注6h。（3）药物干预组（MI组）：结扎左冠状动脉前降支1h,再灌注前10min给予蛋白激酶C抑制剂-GF109203X（O．05mg／kg）耳缘静脉注射持续10min,再灌注即刻行RI-Post组操作,最后心肌再灌注直至6h。实验结束,采用Tunel法检测24只兔梗死区的心肌细胞凋亡,用免疫组化法检测Bax和Bcl-2蛋白在心肌细胞中的表达水平。结果肾脏缺血后处理组与对照组和药物干预组比较,心肌细胞凋亡指数明显减少（P〈0．05）,Bcl-2表达明显增多（P〈0．01）,Bax表达明显减少（P〈0．05）;而药物干预组与对照组相比各检测指标无明显差别（P〉0．05）。结论肾脏缺血后处理可减少急性缺血再灌注后心肌细胞凋亡,并影响Bcl-2、Bax蛋白的表达,从而对缺血心肌产生保护作用,其保护机制可能与激活蛋白激酶C有关。     

培哚普利对心肌缺血再灌注损伤早期Toll样受体4表达的影响

目的观察培哚普利对缺血再灌注早期Toll样受体4蛋白（TLR4）的影响,初步探讨其对心肌缺血再灌注损伤的保护机制。方法30只Wistar大鼠随机分为假手术组、缺血再灌注组及培哚普利组。培哚普利组灌服培哚普利4mg／kg,每日1次,共7d。结扎大鼠左冠状动脉前降支（LAD）,建立大鼠缺血再灌注模型,光镜观察心肌形态学改变,TUNEI,法检测细胞凋亡数及免疫组化检测心肌组织中TLR4表达情况。结果与缺血再灌注组相比,培哚普利组炎症损伤减轻;培哚普利组心肌细胞凋亡数明显低于缺血再灌注组,但高于假手术组（P〈0．05）;培哚普利组心肌组织TLR4表达低于缺血再灌注组,但高于假手术组（P〈0．05）。结论培哚普利可减轻心肌缺血再灌注早期的细胞凋亡,其机制之一可能是通过抑制TLR4所介导的炎症反应实现的。     

心肌缺血/再灌注损伤后的肺组织损伤

目的初步探讨心肌缺血／再灌注损伤对肺组织损伤的可能机制。方法选取雄性成年SD大鼠（4～6月龄）,体重130～160g,建立成年大鼠缺血／再灌注模型。运用CK和MPO试剂盒检测肌酸激酶（CK）和髓过氧化物酶（MPO）的含量,运用双抗体夹心ABC—ELISA法检测细胞间黏附分子-1（ICAM-1）的含量。结果与伪手术组相比,缺血／再灌注大鼠的AN／AAR比值明显增高（P〈0．05）,CK在心肌缺血／再灌注大鼠血清中的含量明显升高（P〈0．05）,MPO与ICAM-1在心肌缺血／再灌注组大鼠血清和肺组织中含量明显升高（P〈0．05）。结论大鼠心肌缺血再灌注损伤后肺组织受到一定的损伤,可能与体循环中炎性介质的作用及肺组织的炎性应激有关。     

非小细胞肺癌Bcl-2基因蛋白表达及其与细胞凋亡和增殖的关系

目的探讨非小细胞肺癌Bcl-2蛋白表达与细胞凋亡和增殖的关系。方法采用SAB免疫组化法检测43例非小细胞肺癌及20例癌旁正常肺组织石蜡包埋标本Bcl-2蛋白及增殖细胞核抗原（PCNA）表达;用TUNEL法检测细胞凋亡。结果肺癌组织Bcl-2蛋白的表达显著高于癌旁肺组织,P〈0．05;肺癌组织中凋亡指数和增殖指数均明显高于癌旁正常肺组织,P〈0．01,Bcl-2表达阳性的肺癌组织细胞凋亡指数明显低于Bcl-2表达阴性组,P〈0．05;高细胞凋亡、增殖指数提示肺癌预后不良,P〈0．05。结论肺癌存在Bcl-2表达上调,Bcl-2异常表达在肺癌发生过程中可能起重要作用。     

葛根素对大鼠局灶性脑缺血再灌注后神经细胞凋亡及Bcl-2、Bax蛋白表达的影响

目的探讨葛根素对大鼠局灶性脑缺血再灌注损伤的保护作用。方法制作大鼠大脑中动脉缺血再灌注模型。40只SD雄性大鼠被随机分为假手术组、缺血组、小剂量葛根素治疗组（小剂量组）、大剂量葛根素治疗组（大剂量组）。应用TTC染色观察梗死体积,应用免疫组化染色及TUNEL染色检测Bcl-2、Bax蛋白表达及凋亡细胞数。结果大、小剂量组梗死体积和凋亡细胞数明显少于缺血组（P〈0.01）,Bcl-2明显多于缺血组（P〈0.01）,小剂量组Bax少于缺血组（P〈0.05）,大剂量组Bax明显少于缺血组（P〈0.01）。大剂量组梗死体积和凋亡细胞数少于小剂量组（P〈0.05）,Bcl-2多于小剂量组（P〈0.05）。大、小剂量组Bax无统计学意义（P〉0.05）。结论葛根素可通过上调Bcl-2蛋白表达,下调Bax蛋白表达减少脑缺血再灌注后神经细胞凋亡,疗效与剂量有关。     

吡格列酮对大鼠缺血再灌注诱导的内质网应激相关的心肌保护作用

目的观察吡格列酮对大鼠心肌缺血再灌注损伤（MIRI）时JNK、p-JNK及caspasc-12蛋白表达的影响,探讨吡格列酮通过JNK通路对内质网应激途径的心肌保护作用。方法Wistar大鼠40只随机分为假手术组（sham组）、缺血再灌注组（I／R组）、I／R＋Pio（吡格列酮）组及I／R＋Pi0＋sP600125组各10只。制作大鼠MIRI模型;TUNEL检测心肌细胞凋亡,免疫组织化学检测各组caspase-12表达变化,westernBlot法检测各组JNK、P-JNK的表达。结果吡格列酮预处理组大鼠心肌细胞凋亡、JNK磷酸化率及caspase-12蛋白表达水平明显比I／R组降低（P〈0．05）,加用JNK抑制剂（SP600125）后上述指标进一步下降,与吡格列酮组比较差异有统计学意义（P〈0．05）。结论缺血再灌注损伤可激活JNK通路,诱导过度的ERS,增加ER凋亡信号介导的细胞凋亡。吡格列酮预处理可减少ER凋亡信号介导的细胞凋亡,JNK信号途径在吡格列酮预处理抑制ER凋亡信号分子活化的机制中发挥重要作用。     

丙酮酸乙酯对大鼠缺血再灌注心肌Bcl-2、Bax和caspase-3表达的影响

目的 探讨丙酮酸乙酯（EP）对缺血再灌注（I／R）心肌细胞凋亡的可能机制。方法 将24只雄性SD大鼠随机分为对照组、I／R组和EP组各8只，均建立Langendorff离体心脏模型，对照组K-H液持续灌流180min；I／R组平衡灌流30min，全心停灌30min，再灌120min；EP组试验程序与I／R组相同，平衡15min后和再灌注期间使用含2mmol／L EP的K-H液。分别以缺口末端标记法及免疫组化法检测各组心肌细胞凋亡指数（AI）及Bcl-2、Bax和caspase-3蛋白表达。结果 I／R组AI和Bcl-2、Bax、caspase-3表达水平均明显高于对照组；与I／R组相比，EP组AI和Bax、caspase-3表达水平明显降低，而Bcl-2表达水平明显升高。结论 EP可抑制离体大鼠I／R损伤过程中的心肌细胞凋亡，其机制可能为下调Bax、caspase-3表达，上调Bcl-2表达。     

Increased AT2R protein expression but not increased apoptosis during cardioprotection induced by AT1R blockade

BACKGROUND: The angiotensin II type 2 receptor (AT2R) is considered to be antigrowth and to mediate apoptosis in several cell types. Whether AT2R upregulation, associated with angiotensin II type 1 receptor (AT1R) blockade and cardioprotection after ischemia-reperfusion (IR), might not result in increased cardiomyocyte (CM) apoptosis has not been documented. OBJECTIVES: To determine whether increased AT2R protein expression, during AT1R blockade after acute IR, is associated with no increase in CM apoptosis. MATERIALS AND METHODS: The recovery of left ventricular (LV) mechanical function after acute IR (30 min of ischemia, 40 min of reperfusion) was measured in isolated Langendorff rat hearts following pretreatment with the AT1R antagonist candesartan (CN) (CN 10 nmol/L) for 40 min before ischemia. The authors established with an initial dose-response curve using escalating concentrations of CN that 10 nmol/L abrogated vasoconstriction induced by angiotensin II (0.1 mmol/L). AT1R and AT2R protein expression (Western immunoblot), CM apoptosis (terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labelling assay and nuclear morphology) and apoptotic markers (Bax, Bcl-2, caspase-3, p53) were assessed in LV tissue. RESULTS: Compared with IR controls, CN improved peak systolic pressure, LV developed pressure and positive dp/dt, and increased AT2R (not AT1R) protein, but did not change the level of apoptosis or the expression of Bax, Bcl-2, caspase-3 or p53. CN also increased AT2R protein after ischemia alone but did not change CM apoptosis or expression of the markers. CONCLUSIONS: Increased AT2R protein expression during AT1R blockade after IR in the isolated Langendorff rat heart is associated with cardioprotection but no increase in CM apoptosis.     

Inhibition of endogenous nitric oxide synthase potentiates ischemia-reperfusion-induced myocardial apoptosis via a caspase-3 dependent pathway

OBJECTIVE: Apoptosis of cardiomyocytes may contribute to ischemia-reperfusion injury. The role of nitric oxide (NO) in apoptosis is controversial. Therefore, we investigated the effect of NO synthase inhibition on apoptosis of cardiomyocytes during ischemia and reperfusion and elucidated the underlying mechanisms. METHODS AND RESULTS: Isolated perfused rat hearts (n = 6/group) were subjected to ischemia (30 min) and reperfusion (30 min) in the presence or absence of the NO synthase inhibitor NG-mono-methyl-L-arginine. Reperfusion induced cardiomyocyte apoptosis as assessed by immunohistochemistry (TUNEL-staining) and the demonstration of the typical DNA laddering. Apoptosis during reperfusion was associated with the cleavage of caspase-3, the final down-stream executioner caspase, whereas the protein levels of the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax were unchanged. Inhibition of the NO synthase drastically increased ischemia and reperfusion-induced apoptosis of cardiomyocytes. Moreover, the NO synthase inhibitor enhanced the activation of caspase-3, suggesting that NO interferes with the activation of caspases in ischemia-reperfusion. CONCLUSION: The results of the present study demonstrate that inhibition of endogenous NO synthesis during ischemia and reperfusion leads to an enhanced induction of apoptosis, suggesting that the endogenous NO synthesis protects against apoptotic cell death. Inhibition of NO synthesis thereby activates the caspase cascade, whereas the Bcl-2/Bax protein levels remained unchanged.     

Postischemic apoptosis and functional recovery after angiotensin II type 1 receptor blockade in isolated working rat hearts

OBJECTIVE: To determine whether chronic angiotensin (AngII) type I receptor (AT1R) blockade inhibits cardiomyocyte (CM) apoptosis and attenuates left ventricular (LV) dysfunction after ischemia-reperfusion (IR) in the isolated working rat heart. METHODS: Postischemic recovery of LV developed pressure, the apoptotic index (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP in situ nick end labeling or TUNEL assay), and changes in expression of apoptotic markers Bcl-2, Bax, p53 and caspase-3 (Western immunoblots) were measured after IR (50 min aerobic perfusion; 25 min global ischemia; 40 min reperfusion) in working rat hearts that were randomized to five groups of six each along 1 week or 3 week pretreatment arms: sham (no drug, no perfusion); no drug, aerobic perfusion; and oral AT1R blockers losartan (30 mg/kg per day) or UP269-6 (3 mg/kg per day), or no drug before IR. RESULTS: Compared to the no drug group after IR, losartan (not UP269-6) preserved functional recovery in 1 and 3 week groups. However, both losartan and UP269-6 reduced the apoptotic index and normalized the increase in Bax, decrease in Bcl-2 and increase in p53 and caspase-3 after IR. A bell-shaped relation between apoptosis and functional recovery after IR was flattened by AT1R blockade. CONCLUSION: The results indicate that IR is associated with LV dysfunction and CM apoptosis involving activation of p53, caspase-3, and increased Bax/Bcl-2 ratio in the working rat heart. Importantly, chronic AT1R blockade inhibited the apoptosis and changes in expression of the markers without improving functional recovery, implying that decrease in apoptosis does not necessarily translate into decreased LV dysfunction.     

厄贝沙坦对大鼠心肌缺血再灌注细胞凋亡与细胞外信号调节激酶通路的影响

目的观察厄贝沙坦对大鼠缺血再灌注心肌细胞凋亡的影响,并探讨其与细胞外信号调节激酶(ERK)通路的关系。方法健康雄性SD大鼠72只,随机分为假手术组、缺血再灌注组、缺血预处理组、厄贝沙坦组、厄贝沙坦+PD-98059组(PD组)。厄贝沙坦灌胃1周后制作大鼠心肌缺血再灌注模型,PD-98059于缺血前15 min尾静脉注射。实验结束后用TTC染色测定心肌梗死面积;免疫组织化学法检测心肌组织BcI-2、Bax表达;Western blot法测定磷酸化ERK的活性;TUNEL检测凋亡细胞指数。结果与假手术组比较,缺血再灌注组、缺血预处理组、厄贝沙坦组、PD组心肌细胞凋亡指数、磷酸化ERK活性及Bcl-2、Bax表达明显增加(P<0.01);与缺血再灌注组比较,缺血预处理组、厄贝沙坦组心肌梗死面积、心肌细胞凋亡指数和Bax表达明显降低,磷酸化ERK活性及Bcl-2表达明显增加(P<0.01);与厄贝沙坦组比较,缺血再灌注组、PD组心肌梗死面积、心肌细胞凋亡指数和Bax表达明显增加,磷酸化ERK活性及Bcl-2表达明显降低,差异有统计学意义(P<0.01)。结论厄贝沙坦能够激活ERK通路,进一步调控Bcl-2、Bax蛋白的表达,抑制再灌注心肌细胞的凋亡。     

肝细胞生长因子的抗鼠心肌细胞凋亡作用与抑制钙敏感受体有关

目的 探讨肝细胞生长因子(HGF)在缺血再灌注损伤中的抗细胞凋亡作用与钙敏感性受体(CaSR)mRNA表达下调的关系.方法 分离的新生鼠心肌细胞,随机分为对照组、模拟心肌缺血再灌注组(I/R组)、特异性CaSR激活剂GdCl3组(GdCl3组)、GdCl3+Na+/Ca2+交换抑制剂NiCl2+L-型钙通道阻滞剂CdCl2组(GdCl3+NiCl2+CdCl2组)、GdCl3+选择性PI3K阻断剂LY294002组(GdCl3+LY294002组)、GdCl3+肝细胞生长因子HGF组(GdCl3+HGF组)、GdCl3+HGF+LY294002组.新生鼠心肌细胞经缺氧处理后在缺血缓冲液中培养2 h,然后在标准培养液中培养24 h,建立模拟心肌缺血再灌注(I/R)模型.TUNEL法检测各组心肌细胞凋亡情况.逆转录聚合酶链反应(RT-PCR)测定各组CaSR mRNA表达.Western blot测定促凋亡蛋白Caspase-3,抗凋亡蛋白Bcl-2和磷脂酰肌醇-3激酶(PI3K).结果 模拟的I/R增强了CaSR mRNA的表达(I/R组:2.62±0.41,对照组:1.00±0.31,P＜0.01)及心肌细胞的凋亡[I/R组:(15.32±2.54)%,对照组:(2.90±1.45)%,P＜0.01].GdCl3进一步增强了CaSR mRNA的表达(GdCl3组:4.46±0.62,I/R组:2.62±0.41,P＜0.01)及心肌细胞的凋亡[GdCl3组:(25.36±2.60)%,L/R组:(15.32±2.54)%,P＜0.01],同时上调了Caspase-3(GdCl3组:1.93±0.28,I/R组:1.50±0.21,P＜0.01),下调了Bcl2的表达(GdCl3组:0.82±0.18,I/R组:1.71±0.30,P＜0.01),抑制了PI3K的磷酸化(I/R组:0.87±0.08,GdCl3组:0.61±0.07,P＜0.01).GdCl3+LY294002组心肌细胞凋亡率显著高于GdCl3组[(32.60±3.42)%比(25.36±2.60)%,P＜0.01],但两组间CaSR mRNA的表达差异无统计学意义.HGF通过抑制Caspase-3(GdCl3+HGF组:1.12±0.23,GdCl3组:1.93±0.28,P＜0.05;GdCl3+HGF+LY294002组:1.87±0.31,GdCl3+LY294002组:3.86±0.47,P＜0.05)和促进Bcl-2的表达(GdCl3+HGF组:2.56±0.54,GdCl3组:0.82±0.18,P＜0.05;GdCl3+HGF+LY294002组:1.68±0.28,GdCl3+LY294002组:0.68±0.13,P＜0.05)减少了I/R和GdCl3诱导的心肌细胞凋亡[GdCl3+HGF组:(11.8±1.89)%,GdCl3组:(25.36±2.60)%,P＜0.05],同时促进了PI3K的磷酸化(GdCl3+HGF组:2.87±0.21,GdCl3组:0.61±0.07,P＜0.05;GdCl3+HGF+LY294002组:2.01±0.14,GdCl3+LY294002组:0.44±0.10,P＜0.05)、下调了CaSR mRNA的表达(GdCl3+HGF组:1.46±0.37,GdCl3组:4.46±0.62,P＜0.01).结论 HGF对心肌细胞的保护作用在I/R诱导的新生鼠心肌细胞凋亡中至少部分与抑制CaSR mRNA表达、促进PI3K的磷酸化途径活化从而下调Caspase-3和上调Bcl-2有关.     

Increased AT(2)R protein expression but not increased apoptosis during cardioprotection induced by AT(1)R blockade

BACKGROUND: The angiotensin II type 2 receptor (AT2R) is considered to be antigrowth and to mediate apoptosis in several cell types. Whether AT2R upregulation, associated with angiotensin II type 1 receptor (AT1R) blockade and cardioprotection after ischemia-reperfusion (IR), might not result in increased cardiomyocyte (CM) apoptosis has not been documented. OBJECTIVES: To determine whether increased AT2R protein expression, during AT1R blockade after acute IR, is associated with no increase in CM apoptosis. MATERIALS AND METHODS: The recovery of left ventricular (LV) mechanical function after acute IR (30 min of ischemia, 40 min of reperfusion) was measured in isolated Langendorff rat hearts following pretreatment with the AT1R antagonist candesartan (CN) (CN 10 nmol/L) for 40 min before ischemia. The authors established with an initial dose-response curve using escalating concentrations of CN that 10 nmol/L abrogated vasoconstriction induced by angiotensin II (0.1 mol/L). AT1R and AT2R protein expression (Western immunoblot), CM apoptosis (terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labelling assay and nuclear morphology) and apoptotic markers (Bax, Bcl-2, caspase-3, p53) were assessed in LV tissue. RESULTS: Compared with IR controls, CN improved peak systolic pressure, LV developed pressure and positive dp/dt, and increased AT2R (not AT1R) protein, but did not change the level of apoptosis or the expression of Bax, Bcl-2, caspase-3 or p53. CN also increased AT2R protein after ischemia alone but did not change CM apoptosis or expression of the markers. CONCLUSIONS: Increased AT2R protein expression during AT1R blockade after IR in the isolated Langendorff rat heart is associated with cardioprotection but no increase in CM apoptosis.     

鼠龄对急性心肌梗死大鼠Bcl-2和Bax表达的影响

目的 建立成年和老年Wistar大鼠急性心肌梗死模型,比较鼠龄对大鼠冠状动脉(冠脉)结扎后不同时间点的凋亡指数及凋亡相关蛋白Bcl-2和Bax表达的影响.方法 115只6～24月龄大鼠中,95只结扎冠脉左前降支,80只(成年、老年大鼠各40只)术后存活,根据鼠龄分为老年心肌梗死组(40只)和成年心肌梗死组(40只),按结扎前降支后的1 h、3 h、5 h、1 d和7 d各分为5组(每组8只).假手术老年组和假手术成年组各10只.心肌梗死组分别于冠脉结扎后1、3、5 h和1、7d时记录血流动力学参数,包括心率、左室收缩压(LVSP)、左室终末舒张压(LVEDP)和左室内压最大收缩和舒张速率(±dp/dtmax).采用伊文蓝-红四氮唑(TTC)染色和原位末端标记(TUNEL)法检测心肌坏死和凋亡程度.免疫组化染色检测心肌内Bcl-2和Bax的形成.结果 大鼠心肌在冠脉结扎后的1 h内即有凋亡出现,并且凋亡达高峰的时间老年心肌梗死组较成年心肌梗死组早.在冠脉结扎3 h,老年心肌梗死组与成年心肌梗死组的凋亡指数分别为(51.90±23.15)%与(18.67±17.15)%,差异有统计学意义(P<0.01).Bcl-2蛋白的表达值老年假手术组和成年假手术组分别为(2.7±0.9)分和(1.8±0.8)分,差异有统计学意义(P<0.05).Bax蛋白的表达两组分别为(6.2±2.9)分和(4.2±1.5)分,差异有统计学意义(P<0.05).结论 老年大鼠抵抗心肌缺血的能力差,鼠龄可能会改变Bcl-2和Bax蛋白的表达而增加心肌细胞凋亡.     

Inhibition of apoptosis after ischemia-reperfusion in rat myocardium by cycloheximide.

Macromolecular synthesis inhibitors protect cells from apoptosis in many systems. To determine whether the protein synthesis inhibitor cycloheximide (CHX) might inhibit apoptosis and protect the myocardium during ischemia-reperfusion, we subjected isovolumic isolated perfused rat hearts to 25 min of normothermic global ischemia followed by reperfusion. We monitored coronary flow, end-diastolic pressure and rate-pressure product (RPP) throughout and assessed apoptosis by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL). Regardless of the treatment regimen (only before ischemia; only during reperfusion; or both before ischemia and during reperfusion), CHX significantly improved functional recovery during reperfusion. These effects were most pronounced when CHX was present during reperfusion. When hearts were treated with CHX only during reperfusion the recovery of sinus rhythm was more frequent in the CHX-treated hearts than control hearts (80% v 53%) and earlier for CHX-treated than control hearts: 6.4 +/- 2 v 19.4 +/- 4.7 min of reperfusion. The maximal RPP recoveries for the CHX-treated hearts were 45 +/- 4.0% (P=0.005) of pre-ischemic values, compared to 26 +/- 3% for controls. In control hearts reperfused for 2 h, TUNEL identified 49.5 +/- 10 intact nuclei and 7.5 +/- 2 fragmented nuclei per 1000 nuclei counted. A significantly lower incidence of labeled nuclei with or without fragmentation was observed in CHX treated hearts: 7.6 +/- 3.4 (P=0.009) intact labeled nuclei and 1.8 +/- 0.7/10(3)fragmented labeled nuclei. Our results suggest that CHX-induced inhibition of apoptosis in reperfused myocardium is cardioprotective and promotes functional recovery in vitro.