The cardioprotective effects of preconditioning with endotoxin, but not ischemia, are abolished by a peroxisome proliferator-activated receptor-gamma antagonist

We investigated whether endogenous ligands of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) protect the heart against ischemia-reperfusion (I/R) injury. The selective PPAR-gamma antagonist GW9662 (2-chloro-5-nitrobenzanilide) was used in rat models of 1) regional myocardial I/R, 2) ischemic preconditioning, and 3) delayed cardioprotection by endotoxin. We also investigated the effects of the selective cyclooxygenase-2 inhibitor, parecoxib, on ischemic preconditioning and delayed cardioprotective effects of endotoxin. Male Wistar rats were anesthetized with sodium thiopentone. Animals were subjected to either 15 or 25 min of regional myocardial I/R and pretreated with the PPAR-gamma agonist ciglitazone (0.3 mg/kg), the PPAR-gamma antagonist GW9662 (1 mg/kg), or GW9662 and ciglitazone. Animals were also subjected to either 1) ischemic preconditioning alone, ischemic preconditioning, and pretreated with either GW9662 or parecoxib (20 mg/kg) or 2) lipopolysaccharide (LPS) (1 mg/kg) alone, LPS, and pretreated with ciglitazone, GW9662, or parecoxib (20 mg/kg). Myocardial infarct size was determined by p-nitroblue tetrazolium staining. The PPAR-gamma antagonist GW9662 (1 mg/kg) abolished the cardioprotection afforded by the potent PPAR-gamma agonist ciglitazone (0.3 mg/kg). Neither GW9662 nor parecoxib affected the cardioprotective effects of ischemic preconditioning. Pretreatment with ciglitazone did not provide additional cardioprotection to LPS-treated animals. Both GW9662 and parecoxib abolished the delayed cardioprotective effects of endotoxin. Thus, we propose that 1) endogenous ligands of PPAR-gamma are being generated by myocardial ischemia in sufficient amounts to attenuate myocardial I/R injury, and 2) that cyclooxygenase-2 metabolites contribute to (or even account for) the cardioprotective effects of endotoxin (second window of protection) by acting as endogenous PPAR-gamma ligands.     

外源性H2S吸入对大鼠肢体缺血／再灌注后心肌损伤的保护作用研究

目的 研究外源性H2S吸入对大鼠双下肢缺血/再灌注后心肌损伤的保护作用.方法 雄性Wistar大鼠23只,随机分为三组:①正常对照组( C组,8只);②缺血/再灌注组(I/R组,8只):应用止血带结扎构建大鼠双下肢缺血/再灌注模型,缺血4 h再灌注4 h.③H2S吸入组(H2S组,7只):大鼠双下肢缺血4 h,再灌注时给予含80 ppm H2S的合成空气持续吸入4 h.观察各组大鼠心肌病理、血浆H2S、肌酸激酶同工酶(CK-MB)、肌钙蛋白-T(TnT)、髓过氧化物酶(MPO)、肿瘤坏死因子-α(TNF-α)水平的变化及心肌胱硫醚-γ-裂解酶(CSE)活性、MPO、TNF-α水平的变化.以免疫组化法观察心肌细胞TNF-α的表达.结果 与C组比较,I/R组血浆CK-MB、TnT、MPO、TNF-α及心肌MPO、TNF-α水平明显上升(P＜0.05),血浆H2S及心肌CSE活性明显下降(P＜0.05),H2S吸入后血浆H2S及心肌CSE活性明显升高;同时,血浆CK-MB、TnT、MPO、TNF-α及心肌MPO、TNF-α水平明显降低(P＜0.05).心肌病理提示I/R组心肌明显肿胀、血管充血,心肌细胞间可见明显分叶核粒细胞浸润,红细胞漏出增多,H2S吸入后心肌损伤明显减轻.心肌TNF-α免疫组化提示I/R组心肌胞浆棕色染色颗粒较C组明显增多,H2S吸入后心肌胞浆棕色染色颗粒明显减少.结论 外源性H2S吸入可以通过降低炎细胞浸润及炎性细胞因子激活而对骨骼肌缺血/再灌注的心肌损伤发挥保护作用.     

Synthetic high-density lipoproteins exert cardioprotective effects in myocardial ischemia/reperfusion injury

Human high-density lipoproteins (HDLs) protect the heart against ischemia/reperfusion injury. In the present study, the cardioprotective effects of synthetic high-density lipoproteins (sHDLs) made of phosphatidylcholine and apolipoprotein A-I were investigated in isolated rat hearts, which underwent a 20-min low-flow ischemia followed by a 30-min reperfusion. The administration of sHDL during the 10 min immediately before ischemia caused a rapid, dose-dependent improvement of postischemic cardiac function: at the maximum dose (2.0 mg of sHDL protein/ml), left ventricular developed pressure (LVDP) recovered to 71.0 +/- 3.2 versus 40.5 +/- 3.8 mm Hg in saline-treated hearts, and coronary perfusion pressure (CPP) increased to 100.3 +/- 6.2 versus 132.0 +/- 9.0 mm Hg. The preservation of postischemic cardiac function was associated with a dose-dependent reduction of creatine kinase release into the coronary effluent. sHDLs administered in the first 10 min postischemia also exerted a significant, dose-dependent improvement of postischemic LVDP, CPP, and creatine kinase release, but the cardioprotective effect was less than when sHDLs were given preischemia. The preservation of postischemic cardiac function by sHDL was mediated through a reduction of cardiac tumor necrosis factor-alpha content and an enhanced cardiac production of prostaglandin E2 and I2. The present experimental data indicate that sHDLs may provide a novel therapeutic approach to clinical conditions in which myocardial ischemia/reperfusion occurs, such as acute coronary syndromes, cardiac surgery, or revascularization procedures.     

气体信号分子硫化氢对大鼠心肌缺血再灌注损伤的保护作用

目的 研究气体信号分子硫化氢(H2S)对大鼠心肌缺血再灌注损伤的保护作用.方法 以硫化氢钠作为H2S供体,建立心肌缺血再灌注损伤动物模型,将实验大鼠按随机原则分为假手术组(对照组)、心肌缺血再灌注组(I/R组)、H2S+I/R组(H2S组)及H2S+K-ATP通道阻断剂glibenclamide+I/R组(H2S+GLI组),监测大鼠心率、动脉压、左心室内压及收缩、舒张功能等血流动力学指标,观察大鼠室性心律失常的发生情况.结果 在心肌缺血前预先给H2S可明显降低大鼠心肌缺血再灌注室性心律失常的发生率(H2S组66.5%与I/R组33.5%,P＜0.05)以及室性心律失常评分[H2S组(2.6±0.7)分与I/R组(4.5±0.8)分,P＜0.05].提前给予K-ATP通道阻断剂glibenclamide,结果发现H2S的抗心律失常作用减弱[H2S组(2.6±0.7)分与H2S+GLI组(4.0±0.6)分,P＜0.05].结论 H2S具有保护大鼠心肌缺血再灌注损伤的作用,其作用机制可能与细胞内K-ATP通道信号转导途径相关.     

Hemodynamic and metabolic effects of hydrogen sulfide during porcine ischemia/reperfusion injury

In awake spontaneously breathing mice, inhaling gaseous hydrogen sulfide (H2S) produced a "suspended animation-like" metabolic status with hypothermia and reduced O2 demand, thus protecting from lethal hypoxia. Murine models may be questioned, however, because due to their large surface area/mass ratio, rodents can rapidly drop their core temperature. Therefore, we investigated whether intravenous H2S (Na2S, sodium sulfide) would induce a comparable metabolic response in anesthetized and mechanically ventilated pigs. Because H2S was reported to improve heart function after myocardial ischemia, we also investigated whether sulfide would influence the noradrenaline responsiveness during reperfusion after aortic occlusion. After 2 h of i.v. sulfide (0.2 mg.kg followed by 2 mg.kg.per h; n=8) or vehicle (n=8), animals underwent 30 minutes of aortic occlusion with nitroglycerine, esmolol, and adenosine-5'-triphosphate adjusted to maintain MAP at 80% to 120% of baseline. During reperfusion, noradrenaline was titrated to keep MAP greater than or equal to 80% of this level. Sulfide reduced heart rate and cardiac output without affecting stroke volume, markedly decreased the time and dose of noradrenaline required to maintain hemodynamic targets, and caused a drop in core temperature concomitant with lower O2 uptake and CO2 production. Although arterial PCO2 and acid-base status were comparable, arterial PO2 was lower in the sulfide group at the end of the experiment. Sulfide attenuated the reperfusion-related hyperlactatemia, although glycemia was higher at the end of the experiment. The parameters of inflammation and oxidative stress did not differ. Intravenous sulfide allowed reducing energy expenditure in an anesthetized large-animal model and improved the noradrenaline responsiveness during reperfusion after aortic occlusion. Investigations are warranted, hence, whether it may also protect other organs after I/R injury.     

瘦素预处理对小鼠心肌冷缺血-再灌注损伤的保护作用研究

目的 本实验旨在研究同种小鼠腹部心脏移植模型中,瘦素预处理对心肌缺血--再灌注损伤的保护作用及其可能机制.方法雄性C57BL/6小鼠行同种间小鼠腹部心脏移植,供体置于4℃UW液中保存6 h.受体随机分为两组:瘦素预处理(Ieptin)组,12只,小鼠重组瘦素50μg/kg溶人生理盐水(normal saline,NS)200 μL中,于心脏移植前腹腔保留;NS对照组,12只,心脏移植前NS 200μL于腹腔保留.另设假手术组,12只.分别于术后6、24 h收获移植心脏与血清标本(每个时间点每组6个标本),评价移植心脏功能及组织形态学变化,检测小鼠移植心脏及血清瘦素的水平,同时测定中性粒细胞活性、炎性细胞因子水平等,并比较两组移植心脏的3周存活时间(每组n=10).结果与对照组比较,瘦素预处理显著降低移植小鼠血清心肌肌钙蛋白Ⅰ,改善移植心脏功能评分;瘦素预处理显著降低心脏移植小鼠术后供心心肌及血清瘦素水平;降低心肌MPO活性,减少血清细胞炎性因子TNF-αd、IL-1β、IL-6的水平;瘦素预处理组60%的移植心脏在术后3周仍然搏动有力,而对照组所有供心在2周内停止跳动.结论瘦素预处理显著减轻心肌冷缺血-再灌注损伤,改善心肌功能,提高移植心脏存活时间,其保护作用可能与减轻炎症反应有关.     

Amiodarone offsets the cardioprotective effects of ischaemic preconditioning against ischaemia/reperfusion injury

Both ischaemic preconditioning (IPC) and amiodarone protect against myocardial ischaemia. We examined whether a combination of IPC and amiodarone demonstrated an additive protective effect in isolated rat hearts (n = 40). The controls (group I) were subjected to ischaemia/ reperfusion injury; group II was subjected to cycles of IPC prior to ischaemia/ reperfusion injury; group III was subjected to ischaemia in the presence of amiodarone (10(-10) mol/1); and group IV was subjected to IPC followed by ischaemia in the presence of amiodarone (10(-10) mol/l). Amiodarone produced the best preserved left ventricular end-systolic pressure and dP/dtmax, less developed ventricular stiffness, the shortest arrhythmia duration, and the smallest infarct size among the groups. All of the myocardial protective effects against ischaemia/reperfusion injury were diminished or abolished when IPC and amiodarone were applied sequentially.     

1,6-二磷酸果糖预处理对离体大鼠心肌缺血再灌注损伤的影响

目的探讨1,6-二磷酸果糖(FDP)预处理对大鼠离体心肌缺血再灌注损伤的保护作用。方法应用Langendorff离体心脏灌注系统制备离体大鼠心脏全心缺血再灌注模型。雄性SD大鼠16只,随机分为2组,每组8只:缺血再灌注组(I/R组)和1,6-二磷酸果糖预处理组(FPC组),所有心脏予以缺血30 min,再灌注60 min。FPC组在持续缺血前用含FDP的K-H液灌注15 min做预处理。记录各组心脏在平衡30 min(T0)、缺血30 min(T1)、再灌注5 min(T2)、再灌注15 min(T3)、再灌注30 min(T4)、再灌注60 min(T5)时的左心室发展压(LVDP)和左心室压力最大上升速率(+dp/dtmax)、左心室舒张末压(LVEDP)和左心室压力最大下降速率(-dp/dtmax)、左心室收缩压(LVSP)、左心室舒张压(LVDP)、心率(HR)、冠状动脉流量(CF),并计算(LVSP-LVDP)3心率。实验结束后取心肌组织用比色法测定其中的超氧化物歧化酶(SOD)和丙二醛(MDA)的含量;常规石蜡固定切片,以免疫组化法测定Bcl-2和Bax的表达及以TUNEL法检测凋亡指数。结果与I/R组相比,FPC组的LVDP、(LVSP-LVDP)3HR、CF在T3~5时点、+dp/dtmax在T2~5时点、HR在T4~5时点升高显著(P<0.05,P<0.01),而LVEDP在T2~5时点降低显著(P<0.05,P<0.01),表明FPC组的心功能显著优于I/R组,且FPC组心肌中的SOD增加而MDA减少、Bcl-2升高而Bax降低、心肌凋亡指数也显著下降。结论 FDP预处理可明显改善大鼠离体缺血再灌注的心功能和减少氧自由基的生成及其对质膜的脂质过氧化作用而保护心肌。     

Wortmannin, a potent antineutrophil agent, exerts cardioprotective effects in myocardial ischemia/reperfusion

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. Wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase, suppresses superoxide production from PMNs. Therefore, we hypothesized that wortmannin could attenuate PMN-induced cardiac dysfunction by suppression of superoxide production from PMNs. We examined the effects of wortmannin in isolated ischemic (20 min) and reperfused (45 min) rat hearts perfused with PMNs. Wortmannin at 10, 20, or 40 nM given to hearts during the first 5 min of reperfusion, significantly improved left ventricular developed pressure (P < .01), and the maximal rate of development of left ventricular developed pressure (P < .01) compared with ischemic/reperfused hearts perfused with PMNs in the absence of wortmannin. In addition, wortmannin significantly reduced PMN infiltration into the myocardium by 50 to 75% (P < .001). Superoxide radical release also was significantly reduced in N-formylmethionyl-leucylphenylalanine-stimulated PMNs pretreated with 10 or 40 nM wortmannin by 70 and 95%, respectively (P < .001 versus untreated PMNs). Rat PMN adherence to rat superior mesenteric artery endothelium exposed to 2 U/ml thrombin was significantly attenuated by 10 to 40 nM wortmannin compared with untreated vessels (P < .001). These results provide evidence that wortmannin can significantly attenuate PMN-induced cardiac contractile dysfunction in the ischemic/reperfused rat heart via attenuation of PMN infiltration into the myocardium and suppression of superoxide release by PMNs.     

Protein kinase C betaII peptide inhibitor exerts cardioprotective effects in rat cardiac ischemia/reperfusion injury

Ischemia followed by reperfusion (I/R) in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. A cell-permeable protein kinase C (PKC) betaII peptide inhibitor was used to test the hypothesis that PKC betaII inhibition could attenuate PMN-induced cardiac dysfunction by suppression of superoxide production from PMNs and increase NO release from vascular endothelium. The effects of the PKC betaII peptide inhibitor were examined in isolated ischemic (20 min) and reperfused (45 min) rat hearts with PMNs. The PKC betaII inhibitor (10 microM; n = 7) significantly attenuated PMN-induced cardiac dysfunction compared with I/R hearts (n = 9) receiving PMNs alone in left ventricular developed pressure (LVDP) and the maximal rate of LVDP (+dP/dt(max)) cardiac function indices (p < 0.01). The PKC betaII inhibitor at 10 microM significantly increased endothelial NO release from a basal value of 1.85 +/- 0.18 pmol NO/mg tissue to 3.49 +/- 0.62 pmol NO/mg tissue from rat aorta. It also significantly inhibited superoxide release (i.e., absorbance) from N-formyl-L-methionyl-L-leucyl-L-phenylalanine-stimulated rat PMNs from 0.13 +/- 0.01 to 0.02 +/- 0.004 (p < 0.01) at 10 microM. Histological analysis of the left ventricle of representative rat hearts from each group showed that the PKC betaII peptide inhibitor-treated hearts experienced a marked reduction in PMN vascular adherence and infiltration into the postreperfused cardiac tissue compared with I/R + PMN hearts (p < 0.01). These results suggest that the PKC betaII peptide inhibitor attenuates PMN-induced post-I/R cardiac contractile dysfunction by increasing endothelial NO release and by inhibiting superoxide release from PMNs.     

缺血预处理对肢体缺血再灌注损伤影响的临床观察

目的 临床观察缺血预处理对肢体缺血再灌注损伤的作用。方法 选择36例四肢手术需充气止血带加压肢体止血的患者，随机分为对照组和缺血预处理组。缺血预处理措施为阻断术肢血流5分钟，然后松止血带，恢复血流灌注5分钟，反复4次。肢体缺血前、再灌注0．5、1．5、3、24小时和72小时分别检测血清丙二醛(MDA)、肌酸磷酸激酶(CK)、天冬氨酸氨基转移酶(AST)和乳酸脱氢酶(LDH)的含量以及超氧化物歧化酶(SOD)活性。结果 肢体缺血再灌注后各时相点与缺血前比较，血清MDA、CK、AST和LDH含量明显低干时照组．SOD活性明显高于时照组．结论 缺血预处理时肢体缺血再灌注损伤鼻有保护作用．     

硫化氢后处理对2型糖尿病大鼠心肌缺血再灌注损伤的保护作用及其与自噬潮的相关性研究

目的观察硫化氢后处理对2型糖尿病大鼠心肌缺血再灌注损伤（I/R）的保护作用及其与自噬潮的关系。 方法将60只成年雄性SD大鼠分为五组：假手术组：仅开胸并分离冠状动脉左前降支,但不结扎阻断血流;I/R组：于冠状动脉左前降支阻断30 min,再灌注4 h;氯喹（CQ）组：于术前1 h腹腔注射10 mg/kg,其余操作同I/R组;硫氢化钠（NaHS）组：于开放左冠状动脉再灌注即刻1 min内静脉注射硫氢化钠0.05 mg/kg,再灌注4 h;CQ + NaHS组：于术前1 h腹腔注射CQ,其余操作同NaHS组;每组12只。连续监测并记录大鼠平衡期15 min、缺血期15 min、再灌注1、2、4 h时大鼠心率、平均动脉压和心率-收缩压乘积（RPP）。再灌注4 h结束后分批处死大鼠并取心脏测定心肌梗死范围,并采用Western blotting法测定微管相关蛋白1轻链3（LC3）、Cathepsin B、Beclin-1、P62表达水平。 结果各组大鼠在各时间点心率的比较,差异无统计学意义（F=0.854,P=0.512）,而平均动脉压及RPP的比较差异均有统计学意义（F=5.182,P=0.007;F=5.082,P=0.008）。且再灌注期2、4 h时,NaHS组平均动脉压为（87 ± 8）mmHg、（91 ± 10）mmHg,RPP为（35.4 ± 4.6）次·mmHg·10³/min、（36.2 ± 5.8）次·mmHg·10³/min,NaHS组明显高于I/R组[平均动脉压分别为（72 ± 10）mmHg、（63 ± 6）mmHg,RPP分别为（28.7±5.8）次·mmHg·10³/min、（26.8 ± 3.8）次·mmHg·10³/min,P均< 0.05]。各组灌注期4 h时,心肌梗死范围区域所占比例及LC3、Cathepsin B、Beclin-1、P62比较差异均有统计学意义（F=96.907、71.164、43.594、57.180、35.967,P均< 0.05）,且NaHS组上述各指标均明显低于I/R组、CQ组、CQ + NaHS组（P均< 0.05）。 结论硫化氢可能通过修复自噬潮对2型糖尿病大鼠心肌I/R损伤发挥保护作用。     

缺血预适应对糖尿病大鼠心肌缺血/再灌注损伤的保护效应

目的 探讨缺血预适应对糖尿病大鼠心肌缺血/再灌注损伤的保护效应.方法 健康雄性大鼠28只,尾静脉注射链脲佐菌素45 mg/kg制备糖尿病大鼠模型,普通饲料喂养4周后随机分为缺血/再灌注（I/R）组和缺血预适应（IP）组.观察两组大鼠缺血前和缺血即刻、缺血15 min、缺血30 min以及再灌注30 min、再灌注2h心电图ST段改变及室性心律失常的发生情况,TTC染色评价心肌细胞坏死情况,TUNEL法检测心肌细胞凋亡情况,免疫组织化学染色法检测心肌组织凋亡相关基因Bcl-2与Bax蛋白表达情况.结果 与I/R组比较,IP组缺血30 min时ST段抬高幅度明显降低[（0.675±0.150）、（0.489±0.161） mV,P＜0.05],室性期前收缩出现时间推迟[（6.47±4.28）、（18.21±5.36） min,t=5.241,P=0.000],室性期前收缩持续时间缩短[（16.71±5.48）、（6.07±4.33） min,t=4.924,P=0.002],室性心动过速、心室颤动发生率显著下降[57.14％ （8/14）与14.29％ （2/14）,x2=5.600,P=0.018;50.00％（7/14）与14.29％（2/14）,x2=4.094,P=0.043],心肌梗死范围缩小[（37.50±11.40）％、（12.50±9.45）％,t=3.211,P=0.006],凋亡指数亦降低[（24.31±3.12）％、（19.01±4.32）％,t=3.227,P=0.006],并伴有凋亡相关蛋白Bcl-2/Bax上调（0.103±0.045、0.221±0.101,t=2.670,P=0.015）.结论 缺血预适应对病程4周糖尿病大鼠心肌缺血/再灌注损伤具有保护效应,其通过上调凋亡相关基因Bcl-2/Bax,减少心肌细胞凋亡.     

氯化镁对大鼠缺血再灌注损伤心肌的保护作用

目的:研究氯化镁对大鼠缺血再灌注损伤心肌是否具有保护性作用,同时探讨氯化镁的心肌保护作用机制。方法:实验于2004-06/07在锦州医学院药理学实验室完成,选用50只SD大鼠,采用整体大鼠急性心肌缺血再灌注损伤模型,用3个不同剂量的氯化镁给大鼠尾静脉注射,测定心肌组织中Ca2+和丙二醛含量以及血清中乳酸脱氢酶含量,并同时记录心电图监测心肌缺血再灌注时心律失常的发生情况率。结果:氯化镁可降低血清中乳酸脱氢酶含量,也能降低心肌组织中的丙二醛和Ca2+含量。氯化镁可减少心肌缺血再灌注损伤时室性心律失常发生率和缩短心律失常的持续时间。给药组再灌注时ST段抬高(mV)程度(其中氯化镁低、中、高剂量组分别为0.16±0.03,0.12±0.02,0.06±0.01)较缺血再灌注组(0.22±0.06)显著降低。结论:氯化镁对心肌再灌注损伤具有保护作用,其机制可能与缓解心肌细胞内钙超负荷和抑制脂质过氧化有关。     

Inhibiting protease-activated receptor 4 limits myocardial ischemia/reperfusion injury in rat hearts by unmasking adenosine signaling

Harnessing endogenous cardioprotectants is a novel therapeutic strategy to combat ischemia/reperfusion (I/R) injury. Thrombin causes I/R injury, whereas exogenous adenosine prevents I/R injury. We hypothesized that blocking thrombin receptor activation with a protease-activated receptor (PAR) 4 antagonist would unmask the cardioprotective effects of endogenous adenosine. The protective role of two structurally unrelated PAR4 antagonists, trans-cinnamoyl-YPGKF-amide (tc-Y-NH(2)) and palmitoyl-SGRRYGHALR-amide (P4pal10), were evaluated in two rat models of myocardial I/R injury. P4pal10 (10 microg/kg) treatment before ischemia significantly decreased infarct size (IS) by 31, 21, and 19% when given before, during, and after ischemia in the in vivo model. tc-Y-NH(2) (5 microM) treatment before ischemia decreased IS by 51% in the in vitro model and increased recovery of ventricular function by 26%. To assess whether the cardioprotective effects of PAR4 blockade were due to endogenous adenosine, isolated hearts were treated with a nonselective adenosine receptor blocker, 8-sulfaphenyltheophylline (8-SPT), and tc-Y-NH(2) before ischemia. 8-SPT abolished the protective effects of tc-Y-NH(2) but did not affect IS when given alone. Adenosine-mediated survival pathways were then explored. The cardioprotective effects of tc-Y-NH(2) were abolished by inhibition of Akt (wortmannin), extracellular signal-regulated kinase 1/2 [PD98059 (2'-amino-3'-methoxyflavone)], nitric-oxide synthase [N(G)-monomethyl-l-arginine (l-NMA)], and K(ATP) channels (glibenclamide). PD98059, l-NMA, and glibenclamide alone had no effect on cardioprotection in vitro. Furthermore, inhibition of mitochondrial K(ATP) channels [5-hydroxydecanoic acid (5-HD)] and sarcolemmal K(ATP) channels (sodium (5-(2-(5-chloro-2-methoxybenzamido)ethyl)-2-methoxyphenylsulfonyl)(methylcarbamothioyl)amide; HMR 1098) abolished P4pal10-induced cardioprotection in vivo. Thrombin receptor blockade by PAR4 inhibition provides protection against injury from myocardial I/R by unmasking adenosine receptor signaling and supports the hypothesis of a coupling between thrombin receptors and adenosine receptors.     

尼可地尔后处理联合预处理对离体心肌缺血/再灌注的作用研究

目的探讨尼可地尔药物后处理、预处理,及二者联合对缺血再灌注损伤离体大鼠心肌的心肌梗死面积,冠脉流出液生化指标,及血流动力学的影响,为临床心脏疾病的治疗提供理论依据。方法48只大鼠随机分为6组,离体心脏Langendorff装置灌流,（1）对照组（Con）：左冠前降支（LAD）阻断40min,复灌120min。（2）缺血后处理组（Pos）：在复灌开始,LAD给予6次短暂开放/钳夹。（3）药物后处理组（Npo）：尼可地尔（Nic）20μmol/L于复灌时给予10min。（4）药物预处理组（Ipc）：在LAD阻断前先给予10min的Nic。（5）联合组（Npp）：LAD阻断前后分别给予Nic。（6）阻滞剂组（Gnp）：灌注液中含有格列本脲（Gli）20μmol/L。结果Pos、Npo、Ipc、Npp同Con比较,LVDP、&#177;dp/dtmax、CF在复灌后各时间点增高（P〈0.05）,Gnp同Con比较差异无统计学意义（P〉0.05）。Npp同Pos、Npo、Ipc比较未表现出叠加效应（P〉0.05）。复灌30min后Pos、Npo、Ipc、Npp中CK、LDH漏出量较少（P〈0.05）,Con同Gnp比较差异无统计学意义。Npp同Pos、Npo、Ipc比较差异无统计学意义。Ipc中心肌梗死区重量从（50.02&#177;2.9）%下降到（22.72&#177;3.6）%（P〈0.05）,Npp和Npo梗死面积分别减小到（23.99&#177;4.3）%和（29.02&#177;2.1）%（P〈0.05）,Pos梗死面积为（34.63&#177;4.1）%（P〈0.05）,Gli取消了Nic的保护作用,心肌梗死面积为（46.82&#177;6.69）%（P〉0.05）。结论缺血后处理,尼可地尔后处理、预处理,及尼可地尔后处理及预处理联合对离体大鼠心肌有保护作用,但尼可地尔后处理联合预处理未表现明显叠加作用。尼可地尔后处理的心肌保护效应可能与再灌注早期的K-ATP通道的激活密切相关。     

药理预适应对兔急性心肌缺血保护作用的研究

目的:观察金纳多和硝酸甘油注射液药理预适应对在体兔心肌缺血/再灌注后热休克蛋白70(HSP70)表达的诱导作用并探讨其心肌保护作用机制。方法新西兰大白兔20只,随机分为4组,每组5只。假手术组开胸后只穿线不结扎,生理盐水组、金纳多组和硝酸甘油组建立心肌缺血/再灌注模型,并于缺血前0.5h分别给予生理盐水、金纳多注射液和硝酸甘油注射液预处理。采用蛋白质免疫印迹法(Western blot)检测各组缺血区和非缺血区心肌组织HSP70含量,并检测血清一氧化氮(NO)、丙二醛(MDA)含量及总超氧化物歧化酶(T SOD)、肌酸激酶(CK)活性变化。结果假手术组HSP70很少表达;其余3组HSP70含量均有明显表达,其中,生理盐水组缺血区和非缺血区HSP70表达分别达假手术组的2.5和2.1倍,金纳多组达17.6和20.7倍,硝酸甘油组达28.1和29.1倍。生理盐水组血清T SOD水平明显降低,MDA和CK水平明显升高(P均<0.01)。金纳多和硝酸甘油组T SOD水平轻度下降,与假手术组和生理盐水组比较差异均有显著性;MDA和CK水平均明显低于生理盐水组,NO明显高于生理盐水组(P<0.05或P<0.01)。硝酸甘油组T SOD、CK活性和NO含量均明显高于金纳多组(P均<0.01),两组MDA水平差异无显著性。结论金纳多和硝酸甘油注射液可诱导心肌缺血/再灌注后HSP70过量表达,从而对心肌起保护作用;金纳多和硝酸甘油的抗氧化作用和细胞保护作用可能与HSP70有关。     

瘦素预处理和缺血预处理在小鼠心肌缺血/再灌注损伤中的心肌保护机制

目的 观察瘦素预处理和缺血预处理(IPC)对心肌缺血/再灌注损伤(MIRI)模型小鼠的心肌保护作用,探讨瘦素参与的机制.方法 将36只C57BL/6小鼠按随机数字表法分为5组:①假手术组(12只);②短暂缺血/再灌注(I/R)组(6只):缺血3 min后再灌注5 min,进行3个短暂的循环;⑨标准I/R组(6只):缺血30 min后再灌注120 min,④IPC组(6只):行3个短暂I/R循环后再进行标准I/R操作;⑤瘦素预处理组(6只):缺血前30min腹腔注射50μg/kg小鼠重组瘦素.假手术组和短暂I/R组分别于再灌注后0(RP刻)、5、30、120 min取血,动态监测血清瘦素水平;其余各组于再灌注后120 min处死小鼠,观察心肌梗死面积、心肌瘦素水平、髓过氧化物酶(MPO)活性,以及血清瘦素、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平.结果 短暂I/R处理后5 min血清瘦素水平即较假手术组同期显著升高[(6.24±2.34)μg/L比(1.35±0.45)μg/L],30 min达峰值[(12.36±1.33)μg/L],之后逐渐下降,与假手术组水平同期比较差异无统计学意义[(1.96±1.33)μg/L比(1.16±0.25)μg/L,P＞0.05].与标准I/R组比较,瘦素预处理组与IPC组均可显著缩小梗死面积[(11.50±2.86)%、(9.00±1.90)%比(37.00±2.53)%],降低心肌瘦素[(8.36±3.42)μg/g、(6.71±2.03)μg/g比(15.51±3.92)μg/g]、MPO((17.10±3.95)μg/g、(13.33±2.88)μg/g比(30.83±4.06)μg/g]以及血清瘦素[(15.03±1.87)μ/L、(11.85±0.72)μg/L比(29.55±2.31)μg/L]、TNF-α[(35.10±10.12)ng/L、(27.04±5.18)ng/L比(81.34±14.20)ng/L]、IL-6[(167.39±72.83)ng/L、(149.13±37.69)ng/L比(477.30±29.09)ng/L]水平(均P＜0.01).结论 低剂量瘦素预处理可模仿经典的IPC以减轻MIRI,瘦素参与IPC的心肌保护机制可能与减轻炎症反应有关.     

血液稀释和缺血预处理对猪心脏缺血再灌注损伤的保护作用

目的在猪心肌缺血再灌注模型上,观察等容血液稀释和缺血预处理对再灌注损伤心肌的保护作用. 方法 18头小型猪建立急性心肌缺血模型,随机分为 3组对照组 (组Ⅰ, n=6),缺血预处理组 (组Ⅱ, n=6),缺血预处理加血液稀释组 (组Ⅲ, n=6),测定心排血量( CO) ,混合静脉血氧饱和度( SvO2,) 、冠状动脉血流量,计算心肌氧供,氧耗量.于钳扎前、解除钳扎后 20,60 min分别测定血浆中丙二醛 (MDA),SOD活性、磷酸激酶( CPK)及肌酸磷酸激酶同功酶( CK-MB) ,自左心耳剪下标本,测定 HSP 70 mRNA表达率. 结果①缺缺血 20 min 时 3组 MAP、 CI及 SVRI明显减低( P< 0.01) ,但 I组下降幅度明显大于 II,III组.再灌注 60 min时, II组 ,III组 HR明显低于对照值( P< 0.01) ,III组 HR的变化则无统计学意义, I组 MAP,CI的下降幅度明显大 I组和 II组 (P< 0.05).②再灌注 20 min及 60 min时, III组的冠脉血流量明显大于 I组( P< 0.05).③再灌注 20 min和 60 min时, 3组 CPK, CPK-MB均较对照值明显升高( P< 0.05- 0.01) ,组 I的升高幅度明显大于组 II, 组 III.组Ⅰ SOD值在再灌注 20 min, 60 min时逐步降低( P< 0.05),组 II, 组 III SOD值有升高趋势,与对照值比较,无统计学意义.再灌注 60 min时,组Ⅰ MDA值明显高于组Ⅱ,组Ⅲ.④组Ⅰ HSP 70 mRNA表达低于组Ⅱ和组Ⅲ. 结论等容血液稀释可明显增强预适应拮抗心肌缺血再灌注造成的心肌损伤.     

费乐地平对兔心肌缺血—再灌注损伤的保护作用

目的：本研究旨在探讨心肌再灌注损伤（ＲＩ）的机制并评价费乐地平（Ｆｅｌｏｄｉｐｉｎｅ，Ｆｅｌ）对ＲＩ的保护作用及其机制。方法：用家兔心肌缺血再灌注模型，分别设对照组、单纯缺血再灌注组及再灌注＋Ｆｅｌ治疗组，设再灌注０．５、１．５和６．０小时３个时相点，测定心肌Ｃａ２＋、丙二醛（ＭＤＡ）含量、中性粒细胞（ＰＭＮ）浸润数、Ｎａ＋Ｋ＋ＡＴＰ酶及Ｃａ２＋Ｍｇ２＋ＡＴＰ酶活性，并观察心肌超微结构改变及测定心肌梗塞范围。结果：心肌再灌注后Ｃａ２＋、ＭＤＡ含量及ＰＭＮ浸润数明显增高，Ｎａ＋Ｋ＋ＡＴＰ酶和Ｃａ２＋Ｍｇ２＋ＡＴＰ酶活性明显降低，其改变以Ｃａ２＋升高发生最快；Ｆｅｌ可使上述指标改变的程度明显减轻（Ｐ＜０．０５～０．０１），并可缩小心肌梗塞范围，改善其超微结构的变化。结论：心肌ＲＩ是多种因素于不同时间所致的一种复合性损伤，Ｆｅｌ对心肌ＲＩ有保护作用，其保护机制可能与其对心肌能量依赖性酶活性的改善有关。