Myocardial protection in reperfusion with postconditioning

Reperfusion is the definitive treatment for coronary occlusive disease. However, reperfusion carries the potential to exacerbate lethal injury, termed ‘reperfusion injury’. Studies have suggested that reperfusion injury events are triggered during the early moments of reflow, and determine, in part, the severity of downstream manifestations of postischemic injury, including endothelial dysfunction, infarction and apoptosis. The application of brief iterative episodes of reflow (reoxygenation) and reocclusion (ischemia, hypoxia) at the immediate onset of reperfusion, which has been termed ‘postconditioning’ by the authors, reduces many manifestations of postischemic injury, notably infarct size, apoptosis, coronary vascular endothelial injury and reperfusion arrhythmias. Cardioprotection with postconditioning has been reported to be comparable with that observed using the gold standard maneuver ischemic preconditioning. In contrast to preconditioning, which exerts its effects primarily during the index ischemia, postconditioning appears to exert its effects during reperfusion alone. Postconditioning modifies the early phase of reperfusion in ways that are just beginning to be understood. It appears to first: reduce the oxidant burden and consequent oxidant-induced injury; secondly, attenuate the local inflammatory response to reperfusion; and thirdly, engage end effectors and signaling pathways implicated in other cardioprotective maneuvers, such as ischemic and pharmacologic preconditioning. Postconditioning seems to trigger the upregulation of survival kinases principally known to attenuate the pathogenesis of apoptosis and possibly necrosis. The postconditioning phenomenon has been reproduced by a number of independent laboratories and has been observed in both large and small animal in vivo models, as well as in ex vivo and cell culture models. In contrast to preconditioning, postconditioning may have widespread clinical application because it can be applied during reperfusion at the point of service for angioplasty, stenting, cardiac surgery and organ transplantation.     

大鼠脑组织缺血再灌注损伤及丹参干预作用实验研究

目的：观察大鼠脑组织缺血再灌注后脑组织损伤变化及丹参的作用。方法：将42只SD大鼠随机分为正常组6只、缺血再灌注组（缺血组）18只和丹参治疗组（丹参组）18只，血管阻断法制作大鼠左侧脑缺血再灌注模型。丹参组于再灌注开始时腹腔注射丹参注射液（5ml／k），而缺血组注入等量生理盐水。观察时点为脑缺血再灌注后12h、24h和48h，观察大鼠脑组织病理变化，检测脑组织含水率及细胞凋亡情况（TUNEL法），检测脑组织丙二醛（malondialdehyde，MDA）、谷氨酸（glutamate，GLU）和7氨基丁酸（gamin-aminobutyric，GABA）含量变化。结果：与正常组比较，缺血组脑组织含水率、凋亡细胞数、MDA水平和GLU含量显著升高，GABA含量显著降低。与缺血组同时点比较，丹参组脑组织病理变化较轻，脑组织含水率、凋亡细胞数、MDA水平和GLU含量显著降低，GABA含量显著升高。结论：血管阻断法能造成显著的大鼠脑缺血再灌注损伤，丹参能有效降低其损伤效应。     

不同预处理中线粒体KATP通道开放对未成熟心肌的作用

目的　了解线粒体ATP敏感性钾通道 (mKATP)开放在不同预处理过程中对幼兔心脏的影响 ,并探讨其机制。方法　幼兔 (小于 2 8d) 34只随机分成 5组 ,对照组 (n =8) :平衡 30min后缺血再灌注 ;二氮嗪预处理组 (n =8) :缺血前二氮嗪 ( 10 0 μmol/L)灌注 5min后重碳酸盐缓冲液 (KH液 )冲洗 10min ,St.ThomasⅡ (STH)停跳 ;二氮嗪 + 5 羟葵酸 ( 5 HD)预处理组 (n =5 ) :二氮嗪 ( 10 0 μmol/L)和 5 HD( 10 0 μmol/L)一起灌注 5min ;缺血预处理 (IPC)组 ( n =8) :平衡 15min后全心缺血 5min ,复灌 10min行IPC ,STH停跳 ;IPC + 5 HD组 (n =5 ) :IPC前用 5 HD ( 10 0μmol/L)灌注 5min。采用LangendOrff模型 ,常温 ( 38℃ )缺血 30min ,复灌 45min。 结果　缺血 /再灌注 (I/R)后二氮嗪组的线粒体评分较IPC组 (P <0 .0 5 )和对照组 (P <0 .0 1)低 ,IPC前给予 5 HD后线粒体评分仍较对照组低 (P <0 .0 5 )。二氮嗪组和IPC组左室发展压力 (LVDP)、左室压力上升和下降最大速率 (±dp/dtmax)恢复在多个时间点上均优于对照组 ,心肌组织ATP含量高于对照组 (P <0 .0 1) ,心肌酶较对照组降低 (P <0 .0 1)。结论　二氮嗪预处理能产生与IPC相似的心肌保护作用 ,并且对线粒体的保护效果较IPC好。mKATP通道和细胞膜KATP     

缺血预处理对肺缺血再灌注损伤中细胞因子生成的影响

目的　探讨缺血预处理 (IPC)对肺缺血再灌注 (I/R)损伤的保护作用及其对细胞因子生成的影响。　方法　 36只大白兔分为 3组 :对照组、I/R组和IPC组。通过阻断左肺门造成兔在体I/R损伤 ,观察IPC对肺I/R损伤的保护作用 ,指标为肺组织湿干重比、肺通透性指数及支气管肺泡灌洗液(BALF)中白细胞分类计数 ;以双抗体夹心酶联免疫吸附试验法检测血清中肿瘤坏死因子α(TNFα)、白细胞介素 6(IL 6)、白细胞介素 8(IL 8)的含量。　结果　肺I/R损伤后 ,I/R组肺组织湿干重比、肺通透性指数及BALF中性粒细胞百分比分别为 9 73± 1 1 4、(41 62± 5 77)× 1 0 - 4和 (58 1± 1 0 0 ) % ;IPC组分别为 6 2 3± 0 69、(2 0 31± 4 0 3)× 1 0 - 4和 (2 3 8± 5 2 ) % ,两组差异有极显著意义 (P <0 0 1 )。I/R组血清TNFα、IL 6和IL 8含量分别为 (0 90 78± 0 1 0 6 2 )、(0 2 1 3 7± 0 0 598)和 (0 72 1 1± 0 0 979)ng/ml,IPC组分别为 (0 7478± 0 0 843)、(0 1 2 71± 0 0 0 89)和 (0 590 3± 0 0 746)ng/ml,较I/R组显著降低 (P <0 0 1 )。　结论　IPC对I/R损伤有显著的保护作用 ,机理可能与其抑制炎性细胞因子TNFα、IL 6和IL 8的合成和释放 ,从而减轻中性粒细胞的浸润与激活有关。     

垂体中间叶激素对心血管系统作用的研究进展

垂体中间叶激素(IMD)是降钙素基因相关肽超家族成员之一,其作用与降钙素基因相关肽、肾上腺髓质素相似。IMD通过结合降钙素受体样受体与受体活性修饰蛋白1~3所组成的受体复合物发挥作用。研究发现,IMD在缺血再灌注损伤、糖尿病、冠状动脉疾病、心室重构等,尤其在心血管系统疾病中具有强大的保护作用,且该保护作用主要是通过降低体内氧化应激水平从而减轻损伤所致。     

钙蛋白酶活化在小鼠心肌缺血再灌注损伤中的作用

目的:探讨钙蛋白酶在小鼠心肌缺血/再灌注(Ischemia/Reperfusion,I/R)损伤中的作用。方法:采用结扎/松解左冠状动脉前降支的方法建立小鼠心肌I/R模型。将实验动物随机分为假手术组、I/R组(冠状动脉结扎45 min,再灌注3h)及PD+I/R组(I/R前30 min静脉注射钙蛋白酶抑制剂-PD150606 1 mg/kg)。再灌注结束后,测定各组心肌梗死面积、细胞色素C含量、caspase-3活性。结果:与I/R组相比,PD150606预处理组心肌梗死区域面积明显减小,且PD150606能明显抑制由I/R引起的细胞色素C含量及caspase-3活性增加。结论:钙蛋白酶活化介导的心肌细胞凋亡在小鼠心肌I/R损伤中发挥了重要的作用。     

糖尿病小鼠局灶性脑缺血再灌注损伤中脑周细胞的变化

目的 探讨糖尿病高血糖状态下局灶脑缺血再灌注损伤中脑周细胞的变化特点.方法 采用四氧嘧啶一次性腹腔注射制备1型糖尿病高血糖C57BL/6小鼠模型,以线栓法为基础使大脑中动脉缺血建立局灶性脑缺血再灌注小鼠模型,使用行为学、组织化学、qRT-PCR及Western blot等方法,对比观察假手术组(空白对照组)、正常血糖脑缺血再灌注组(缺血组)、糖尿病高血糖脑缺血再灌注组(高糖并缺血组)大脑皮质区周细胞数量改变和α-平滑肌肌动蛋白(α-SMA)的相对表达情况.结果 免疫组化及TTC染色显示,与空白对照组比较,缺血组缺血1h再灌注24 h后脑组织中α-SMA阳性细胞数量明显增多,梗死脑组织水肿明显(P＜0.05);高糖并缺血组再灌注24 h,α-SMA阳性细胞数目较同期缺血组更多,梗死区域水肿极严重(P＜0.05);qRT-PCR和Western blot分别显示高糖并缺血组α-SMA蛋白对应基因、α-SMA蛋白的相对表达量均高于缺血组(P＜0.05).结论 糖尿病高血糖与缺血再灌注两种损伤机制同时作用于脑组织时,使脑组织损伤更严重,损伤区域α-SMA的表达增强,周细胞数量明显增加.     

冷血停搏液对法洛四联症婴幼儿心肌代谢的影响

目的：通过临床应用，评价冷血停搏液对未成熟心肌代谢的影响。方法：50例行择期法洛四联症根治术病儿随机分为2组，对照组用10℃改良St.Thomas 1停搏液（CCP），试验组用冷血停搏液（BCP），阻断升主动脉前，开放升主动脉1，3，10min分别由冠状静脉窦和动脉同时取血测定血气，电解质，乳酸，丙二醛（MDA）等含量。结果：再灌注后BCP组心肌氧提取率，乳酸摄取率恢复较快（P＜0．05），再灌注各时点两组均出现钾离子释放和MDA升高；再灌注后BCP组钙离子摄取较低（P＜0．05），结论：冷血停搏液对再灌注后的离子平衡，氧化谢，糖代谢恢复优于冷晶体停搏液。     

高位硬膜外阻滞对猪急性心肌缺血/再灌注损伤时血浆TXB2和6-keto-PGF1α水平的影响

目的探讨0.5%布比卡因高位硬膜外阻滞对急性心肌缺血/再灌注损伤时血栓素B2(TXB2)和6-酮-前列腺素F1α(6-keto-PGF1α)的影响.方法健康雄性家猪20只,体重(23.0±2.5)kg,随机分为布比卡因组(Ⅰ组)、生理盐水组(Ⅱ组).静注10mg.kg-1硫喷妥钠后,气管插管,静点琥珀胆碱和芬太尼控制呼吸,维持麻醉.T3～4穿刺置入硬膜外导管,按分组分别硬膜外注射0.5%布比卡因和生理盐水各2ml,15min后结扎左冠脉前降支40min.分别在给药前和结扎40min时、开放后1h、3h、5h抽取右心房血,测定血浆TXB2、6-keto-PGF1α的浓度.给药前所测定的心率(HR)、平均动脉压(MAP)、中心静脉压(CVP)作为基础值.结果Ⅱ组各时点血液动力学无明显变化,Ⅰ组HR、MAP和CVP分别下降22%、25%和28%.两组再灌注后1h、3h及5h TXB2、TXB2/6-keto-PGF1α比值逐渐升高,且均显著高于给药前和结扎40min.Ⅰ组升高程度显著低于Ⅱ组(P＜0.05).而6-keto-PGF1α组内组间比较,变化趋势与TXB2恰相反.Ⅰ组有1只因室颤而死亡,Ⅱ组有4只(P＜0.05).结论心肌缺血/再灌注损伤与TXB2和6-keto-PGF1α有一定关系,高位硬膜外阻滞通过调节缺血/再灌注后血栓素A2和前列环素的平衡在一定程度上减轻了心肌缺血/再灌注损伤.     

Effect of coenzyme Q10 supplementation on mitochondrial function after myocardial ischemia reperfusion.

BACKGROUND: Coenzyme Q10 (CoQ10) protects myocardium from ischemia-reperfusion (IR) injury as evidenced by improved recovery of mechanical function, ATP, and phosphocreatine during reperfusion. This protection may result from CoQ10's bioenergetic effects on the mitochondria, from its antioxidant properties, or both. The purpose of this study was to elucidate the effects of CoQ10 supplementation on mitochondrial function during myocardial ischemia-reperfusion using an isolated mitochondrial preparation. METHODS: Isolated hearts (n = 6/group) from rats pretreated with liposomal CoQ10 (10 mg/kg iv, CoQ10), vehicle (liposomal only, Vehicle), or saline (Saline) 30 min before the experiments were subjected to 15 min of equilibration (EQ), 25 min of ischemia (I), and 40 min of reperfusion (RP). Left ventricular-developed pressure (DP) was measured. Mitochondria were isolated at end-equilibration (end-EQ), at end-ischemia (end-I), and at end-reperfusion (end-RP). Mitochondrial respiratory function (State 2, 3, and 4, respiratory control index (RCI, ratio of State 3 to 4), and ADP:O ratio) was measured by polarography using NADH (alpha-ketoglutarate, alpha-KG)- or FADH (succinate, SA)-dependent substrates. RESULTS: CoQ10 improved recovery of DP at end-RP (67 +/- 11% in CoQ10 vs 47 +/- 5% in Vehicle and 50 +/- 11% in Saline, P < 0.05 vs Vehicle and Saline). CoQ10 did not change preischemic mitochondrial function. IR decreased State 3 and RCI in all groups using either substrate. CoQ10 had no effect in the mitochondrial oxidation of alpha-KG at end-I. CoQ10 improved State 3 at end-I when SA was used (167 +/- 21 in CoQ10 vs 120 +/- 10 in Saline and 111 +/- 10 ng-atoms O/min/mg protein in Vehicle, P < 0.05). Using alpha-KG as a substrate, CoQ10 improved RCI at end-RP (4.2 +/- 0.2 in CoQ10 vs 3.2 +/- 0.2 in Saline and 3.0 +/- 0.3 in Vehicle, P < 0.05). Using SA, CoQ10 improved State 3 (181 +/- 10 in CoQ10 vs 142 +/- 9 in Saline and 140 +/- 12 ng-atoms O/min/mg protein in Vehicle, P < 0.05) and RCI (2.21 +/- 0.06 in CoQ10 vs 1.85 +/- 0.11 in Saline and 1.72 +/- 0.08 in Vehicle, P < 0.05) at end-RP. CONCLUSIONS: The cardioprotective effects of CoQ10 can be attributed to the preservation of mitochondrial function during reperfusion as evidenced by improved FADH-dependent oxidation.