再灌注早期渐增灌注压力对缺血再灌注心肌保护作用的实验研究

目的 探讨心肌缺血后再灌注时渐增灌注压力是否具有与标准心肌缺血后处理相同的心肌保护用以及其机制.方法 观察持续缓慢升高灌注压力对缺血再灌注后心肌的冠脉流出液中cTnI含量及冠脉流量、心肌细胞超微结构变化的影响以及P-Akt的表达.结果 持续缓慢升压组能有效促进缺血再灌注心脏的冠脉流量恢复,冠脉流出液中cTnI含量减少,P-Akt高表达,同时电镜观察显示细胞超微损伤亦减轻.结论 持续缓慢升高灌注压力对离体缺血再灌注心脏具有保护作用,PI3K/Akt/GSK-3β通路可能是其心肌保护作用的信号传导通路之一.     

维拉帕米抗缺血心肌脂质过氧化与促进前列环素合成作用

“钙拮抗剂维拉帕米对离体大鼠心脏缺氧再给氧损伤和在体大鼠心脏缺血再灌注损伤均有预防性保护作用。维拉帕米能显著减少缺血心肌磷酸肌酸激酶释放,降低丙二醛含量和保护超氧化物歧化酶活性。在整体动物心肌缺血再灌注损伤实验,维拉帕米能显著促进缺血心肌前列环素合成。结果表明维拉帕米对心肌缺血再灌注损伤的保护作用与抗脂质过氧化有关,其促进前列环素合成作用可能与其抗心肌缺血有关。     

巯甲丙脯酸对实验性高血压大鼠心肌缺血—再灌注损伤的保护作用

为探讨巯甲丙脯酸（ｃａｐｔｏｐｒｉｌ）对高血压肥大心肌缺血－再灌注的影响，本实验以造成大鼠腹主脉狭窄的方法复制高血压模型，观察了应用巯甲丙脯酸的高血压下大鼠离体心脏缺血－再灌注的变化，结果显示未用药的高血压大鼠，离体心脏在缺血－再灌注后出现心肌细胞乳酸脱氢酶的漏出和丙二醛生成增加及组织钙含量增加等损伤性变化，而预先应用巯甲脯酸处理的高血压大鼠，乳酸脱氢酶和丙二醛增高的情况明显减轻，避免了钙在心肌内     

超氧化物歧化酶对心肌再灌注损伤中L-精氨酸双重作用的影响

目的:观察L-精氨酸在大鼠心肌缺血再灌注损伤中的作用和在再灌注过程中加入氧自由基清除酶超氧化物歧化酶(SOD)对其产生的影响。方法:在心肌缺血前给予含不同浓度L-精氨酸的KH灌注液,再灌注早期给予SOD,再灌注期间测定心脏功能指标及冠状动脉流出液心肌酶释放量和一氧化氮(NO)含量,测定心肌组织丙二醛(MDA)含量,观察心肌超微结构改变。结果:心肌缺血前给予含低浓度L-精氨酸的KH液(10mmol.L-1)灌注心脏,再灌注30min时左心功能指标LVSP恢复值为(70.3±3.9)%,心肌酶LDH释放(56±4.1)U.L-1,较对照组改善,提示能减轻心肌缺血再灌注损伤;心肌缺血前给予含高浓度L-精氨酸的KH液(100mmol.L-1)灌注心脏,左心功能指标LVSP恢复值为(31.6±4)%,心肌酶LDH释放(150±15.9)U.L-1,MDA含量明显增加(4.5±0.23)nmol.mgpr-1,提示加重了心肌缺血再灌注损伤;而同时给予含100mmol.L-1L-精氨酸和SOD(1 000U.L-1)的KH液灌注心脏后,再灌注30min时左心功能指标LVSP恢复值为(88.6±3.8)%,心肌酶LDH释放(32±3.5)U.L-1,MDA含量(0.80±0.08)nmol.mgpr-1,提示明显减轻了心肌缺血再灌注损伤。结论:SOD和L-精氨酸联合应用可以减少NO的不良反应,从而更好地发挥NO的有益作用,在减轻心肌缺血再灌注损伤上效果最优。     

蒙古黄芪总黄酮对大鼠心肌缺血再灌注损伤的保护作用

目的研究蒙古黄芪总黄酮对大鼠心肌缺血再灌注损伤的保护作用及其机制。方法采用结扎大鼠左冠状动脉前降支法,缺血90 min,再灌注24 h,建立心肌缺血再灌注损伤模型。观察大鼠心电图S-T段变化,用氯化三苯基四氮唑(TTC)对心肌染色,观察心肌梗死面积及测定血清乳酸脱氢酶、肌酸激酶、心肌组织超氧化物歧化酶、丙二醛含量,探讨蒙古黄芪总黄酮对心肌缺血再灌注损伤的保护作用。结果蒙古黄芪总黄酮90、270 mg·kg-1可以使心肌缺血再灌注损伤大鼠心电图S-T段降低及降低大鼠血清中乳酸脱氢酶、肌酸激酶的释放;30、90、270 mg·kg-1剂量可减少大鼠心肌梗死面积;270 mg·kg-1剂量减少大鼠心肌组织丙二醛的产生,提高心肌组织超氧化物歧化酶活力。结论蒙古黄芪总黄酮可以使缺血再灌注损伤大鼠心肌缺血程度降低,减少心肌梗死面积,对缺血再灌注损伤具有一定的保护作用,其作用机制可能通过抑制乳酸脱氢酶、肌酸激酶的释放,降低心肌组织氧化产物丙二醛含量、提高内源性氧自由基清除剂超氧化物歧化酶的活力,减轻缺血再灌注损伤后氧自由基对心肌细胞膜脂质过氧化损伤有关。     

巯甲丙脯酸对实验性高血压大鼠心肌缺血-再灌注损伤的保护作用

为探讨巯甲丙脯酸（ｃａｎｔｏｐｒｉｌ）对高血压肥大心肌缺血－丙灌注的影响，本实验以造成大鼠腹主动脉狭窄的方法复制高血压模型，观察了应用巯甲丙脯酸的高血压大鼠肉体心脏缺血－再灌注的变化。结果显示未用药的高血压大鼠，离体心脏在缺血－再灌注后出现心肌细胞乳酸脱氢酶的漏出和丙二醛生成增加及组织钙含量增加等损伤性变化，而预先应用巯甲丙脯酸处理的高血压大鼠，乳酸脱氢酶和丙二醛增高的情况明显减轻，避免了钙在心肌内过多积聚。表明巯甲丙脯酸具有抗高血压肥大心肌缺血－再灌注损伤的作用。     

维拉帕米防治缺血和缺血／再灌注性室颤的探讨

目的：探讨维拉帕米抗缺血及缺血／再灌注性室颤的机理。方法：用高效液相色谱－电化学法测定豚鼠离体心灌注液中去甲肾上腺素（NE）含量。结果：维拉帕米组在灌止灌注时心脏NE释放明显低于对照组（P＜0．01）,缺血及缺血／再灌注性室颤发生率维拉帕米组显著低于对照组（P＜0．01）。结论：维拉帕米抑制缺血心肌NE释放为其抗缺血及缺血／再灌注室颤的机理之一。     

左旋卡尼汀对大鼠心脏缺血-再灌注损伤能量代谢的影响

目的：观察左旋卡尼汀对离体大鼠心脏缺血-再灌注损伤的作用及对心肌细胞能量代谢的影响。方法：将制备成功的Langendorff离体心脏模型随机分成3组（各8只）。正常对照组（CON组）：K—H液灌注65min；左旋卡尼汀组（L—CAR组）：离体心脏用K—H液平衡15min后，K—H液中加入5mmol／L左旋卡尼汀继续灌注20min．然后全心停灌20min，再用相同的液体复灌30min；心肌缺血-再灌注组（MIRI组）：整个实验过程同L—CAR组．但灌注液中不含左旋卡尼汀。比色法测定冠脉流出液中乳酸脱氢酶（LDH）含量，高效液相色谱法测定再灌注末心肌组织中腺苷酸的含量。结果：缺血前各组LDH活性差异无统计学意义（P〉0．05），再灌注末L—CAR组LDH含量明显低于MIRI组（P〈0．01），而心肌组织ATP、ADP、总腺苷酸水平及能荷则高于该组（P〈0．05，P〈0．01）。结论：左旋卡尼汀对缺血-再灌注心肌有保护作用，其保护机制与改善心肌能量代谢有关。     

参麦注射液对正常及缺血再灌注离体豚鼠心脏的影响

目的观察参麦注射液(SM)对正常及缺血再灌注离体豚鼠心脏的影响。方法采用正常Langendorff灌流及缺血再灌注离体豚鼠心脏模型,观察SM对冠脉流量的影响,测定冠脉流出液中乳酸脱氢酶(LDH)活性及心肌组织丙二醛(MDA)、超氧化物歧化酶(SOD)的活性。结果SM可显著提高正常及缺血-再灌注离体豚鼠心脏的冠脉流量,减少缺血-再灌注后LDH的漏出总量,降低缺血再灌后心肌组织MDA的含量,升高SOD的活性。结论SM可增加正常及缺血-再灌离体豚鼠心脏冠脉流量,减轻缺血-再灌引起的心肌损伤。     

山楂叶总黄酮对大鼠心肌缺血再灌注损伤的心电图、一氧化氮及丙二醛变化的影响

目的：观察山楂叶总黄酮（hawthorn leaves flavonoids，HLF）对大鼠心肌缺血再灌注损伤的心电图、NO及丙二醛（MDA）变化的影响。方法：结扎大鼠冠状动脉左前降支，使心肌缺血30min，再灌注60min，制备急性心肌缺血再灌注损伤模型，缺血前10min，腹腔注射HLF（12．5、25．0、50．0mg／kg）。动态观察心电图，同时监测心电图ST段的变化，用硝酸还原酶法测定血清中NO浓度，采用硫代巴比妥钠（TAB）比色法测定组织内MDA含量。结果：HLF（12．5、25．0、50．0mg／kg）能减轻缺血再灌注损伤心肌心电图ST段变化，提高血清NO的浓度，降低心肌缺血再灌注时心肌组织MDA含量。结论：HLF能改善心肌缺血再灌注损伤心电图变化，对损伤心肌有保护作用，其机制与增加NO浓度、抗脂质过氧化的作用有关。     

Beneficial effects of befunolol on post-hypoxic recovery of cardiac contractility and myocardial metabolism.

The present study was undertaken to determine whether befunolol (BFE 60, CAS 39543-79-8) a beta-adrenoceptor blocking agent, improves post-hypoxic contractile and metabolic recovery of perfused hearts. Isolated rat hearts were perfused for 20 min under hypoxic conditions, followed by 45-min reoxygenation. Hypoxia/reoxygenation induced less than 5% post-hypoxic recovery of cardiac contractile force, incomplete return of resting tension of hearts, accumulation of tissue calcium, and release of purine nucleosides and bases, and creatine kinase from the heart. When hypoxic hearts were treated with 500 mumol/l befunolol from 0 to 10 min of hypoxic perfusion, marked recovery of contractile force (more than 50% of the pre-hypoxic value), complete suppression of the tissue calcium accumulation and significant suppression of the increase in creatine kinase activity of the perfusate were seen after reoxygenation. This treatment also significantly prevented the release of purine nucleosides and bases during hypoxia. These results suggest that treatment with befunolol during hypoxic perfusion is beneficial for post-hypoxic recovery of cardiac function and myocardial metabolism, probably through a mechanism of suppression of transmembrane flux of substrates, ions and enzymes. Cardiac contractile force upon the onset of hypoxia declined more rapidly and myocardial high-energy phosphate content after 10 min of hypoxia was significantly higher in befunolol-treated hearts than in hearts without treatment. Thus, energy-sparing effects may also contribute to the beneficial post-hypoxic recovery of cardiac function and metabolism.     

纳洛酮对离体大鼠心脏缺血再灌流损伤的保护作用

本实验采用离体大鼠心脏Langendorff灌流装置.使心脏停灌(旷置)40 min后再恢复灌流30min.夏制心肌缺血再灌流损伤.观察了纳洛酮对再灌流后冠脉流出液中乳酸脱氢酶(LOH)活性,心肌细胞内钙含量.心肌脂质过氧化产物——丙二醛(MDA)含量和超氧化物歧化酶(SOD)活力变化的影响。结果表明.再灌流后应用纳洛酮能显著减少心肌LDH的释放量.心肌细胞内钙聚集、心肌MDA的生成量及SOD活力降低的程度.提示纳洛酮对缺血再灌流心肌具有保护作用。     

Experimental conditions determine effects of ascorbic acid on reperfusion injury: comparison of tissue damage with hemodynamic parameters in rat isolated hearts.

Restoration of coronary blood flow after myocardial ischemia is always a matter of urgency, but the resulting surgical or drug-induced reperfusion of ischemic tissue is often associated with myocardial functional disturbances and tissue injury. The present study was carried out to select experimental conditions under which optimal effects of antioxidants can be observed on the adverse effects of reperfusion of ischemic myocardium. The release of lactate dehydrogenase (LDH) and changes in hemodynamic parameters were compared in two models of cardiac reperfusion injury in rat isolated hearts. LDH release from electrically-stimulated hearts perfused under constant flow and with initial (5 min) reperfusion in calcium-free buffer was greater than that from hearts perfused under constant pressure in which ischemia was induced by reduced flow. Combined SOD+catalase was a weak inhibitor of LDH release in both models, ascorbic acid being more potent under constant pressure than under constant flow conditions. A longer ischemic period enhanced the inhibitory effect of ascorbate. Contractility and ventricular end-diastolic pressure recovered slowly during perfusion under constant flow and brief calcium removal, but remained unphysiological under constant pressure. SOD+catalase had no effect on hemodynamic parameters. Ascorbic acid exacerbated ischemia+reperfusion-induced changes in contractility, ventricular pressure, heart rate and coronary flow under constant pressure, but facilitated recovery of contractility on reperfusion under constant flow and brief calcium removal. In studies on antioxidants, different experimental conditions appear to be necessary to observe beneficial effects on tissue damage on the one hand and on hemodynamics on the other. Mild to moderate ischemia, with sustained pacemaker activity, appears to be the condition under which antioxidants provide hemodynamic improvement. In isolated rat hearts, biochemical parameters of tissue damage may be misleading for the effects of antioxidants.     

Cardiac effects of ST-6, a novel cyclohexane dicarboximide derivative

Na(+) channel blockade is thought to be involved in the cardioprotection against ischemia/reperfusion injury. We synthesized various cyclohexane dicarboximides and examined their cardioprotective actions. Some of these derivatives had local anesthetic action and were capable of enhancing post-hypoxic contractile recovery of the isolated perfused rat heart. Among them, 2-[4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]butyl]hexahydro-1H-isoindol-1,3(2H)-dione hydrochloride (ST-6) was most effective in the enhancement of post-hypoxic contractile recovery of isolated perfused rat hearts subjected to 20-min hypoxia and 45-min reoxygenation. This enhanced recovery by 30 mg/min of ST-6 was associated with attenuation of Na(+), but not of Ca(2+), accumulation during ischemia and prevention of creatine kinase release from the heart during reperfusion. When hearts subjected to 30-min ischemia followed by 60-min reperfusion were pretreated with 30 muM ST-6, the post-ischemic contractile recovery was enhanced and ischemia-induced accumulation of Na(+), as well as reperfusion-induced accumulation of Na(+) and Ca(2+), was attenuated. Also the reperfusion-induced release of creatine kinase was reduced, while restoration of myocardial high-energy phosphates was enhanced during reperfusion. Na(+) channel blockade by ST-6, as assessed by the depression of the Vmax of the action potential, was similar to that produced by flecainide but more pronounced than with either lidocaine or disopyramide. ST-6, 1, or 2 mg/kg i.v. or 10 mg/kg i.p., abolished ventricular fibrillation induced by 4 min of ischemia and subsequent 4 min of reperfusion in rats. The prevention of ventricular fibrillation by the continuous injection of 0.2 mg/kg per min ST-6 from the first min after ischemia to the end of reperfusion was similar in degree to that produced by 0.1 mg/kg/min lidocaine or 0.5 mg/kg/min diltiazem. The former treatment elicited a transient decrease in the systemic blood pressure in anesthetized rats during ischemia, whereas treatment with the latter did not reduce systemic blood pressure. These findings suggest that ST-6 may have cardioprotective effects in ischemia/reperfusion injury.     

Preservation of mitochondrial function by diazoxide during sustained ischaemia in the rat heart

1. A possible mechanism for the action of the K(ATP) channel opener diazoxide on the improvement of energy metabolism of ischaemic/reperfused hearts was examined. 2. Isolated, perfused rat hearts were subjected to 40 min ischaemia followed by 60 min reperfusion. Diazoxide at concentrations of 3 to 30 microM was present in the perfusion buffer for the last 15 min of pre-ischaemia. 3. Treatment of the perfused heart with diazoxide enhanced the post-ischaemic recovery of rate-pressure product, attenuated the post-ischaemic rise in left ventricular end-diastolic pressure, and suppressed the release of creatine kinase and purine nucleosides and bases from the reperfused heart. Treatment of the heart with diazoxide also restored myocardial ATP and creatine phosphate and attenuated the decrease in mitochondrial oxygen consumption rate after reperfusion. This attenuation was maintained at the end of ischaemia as well as at the end of reperfusion. 4. In another set of experiments, myocardial skinned bundles were incubated for 30 min under hypoxic conditions in the presence and absence of diazoxide, and then the mitochondrial oxygen consumption rate was determined. Hypoxia induced a decrease in the mitochondrial oxygen consumption rate of the skinned bundles to approximately 40% of the pre-hypoxic value. In contrast, treatment of the bundles with 30 microM diazoxide preserved the normal mitochondrial oxygen consumption rate during hypoxia. This effect was abolished concentration-dependently by the combined treatment with either the K(ATP) channel blocker glibenclamide or 5-hydroxydecanoate. 5. These results suggest that diazoxide is capable of attenuating ischaemia/reperfusion injury of isolated perfused hearts due to preservation of mitochondrial function during ischaemia.     

心律平对缺血再灌注心脏保护作用的实验研究

目的 探讨心律平（抗心律失常药）对缺血再灌注心肌的保护效果.方法 大鼠24只,离体心脏灌注,随机分为试验组与对照组：2组均应用停跳液,心脏停跳后,停灌注120 min,再灌注30 min,实验组在停跳液中加入心律平.分别测定再灌注5,10,30 min时,左心室收缩功能（LVDPi）及冠脉流量（Vi）,检测冠脉流出液中CPK-MB、LDH、TnT量;再灌注30 min,取左心室前壁内膜,检查心肌超微结构变化.结果 再灌注5,10,30 min实验组左心肌收缩功能恢复均好于对照组;漏出液中CPK-MB、LDH、TnT含量均少于对照组组.实验组超微结构损害较对照组轻.结论 停跳液中加用心律平,可减少缺血再灌注损伤,有显著的心肌保护作用.     

Mechanisms of protective effects of berbamine on ischemia/reperfusion injury in isolated rat heart.

Isolated perfused rat heart model was used to observe the protective effects of berbamine on myocardial ischemia/reperfusion injury. The hearts were significantly injured by 40 min global ischemia followed by 20 min reperfusion. Berbamine could significantly improve heart function, prevent ventricular fibrillation, reduce CK release, preserve Na,K-ATPase activity, and reduce Na+ gain and K+ loss during ischemia and Ca2+ overload during reperfusion. With the use of low temperature ESR technique, in hearts subjected to 40 min ischemia and 15 sec reperfusion, oxygen-centered free radical signals became much more intense. In the presence of berbamine, these signals decreased. Results showed that berbamine could alleviate myocardial ischemia/reperfusion injury. This effect might be due to: 1) preserved myocardial Na,K-ATPase activity and inhibition of sodium overload at the end of ischemia, which might further lead to attenuation of reperfusion-induced calcium overload, and 2) reduction of oxygen free radical generation during reperfusion.     

新化合物TG6对心肌缺血/再灌注损伤的影响及机制研究

目的研究TG6对心肌缺血/再灌注损伤的保护作用及机制。方法采用整体大鼠心肌缺血/再灌注（I/R）实验,离体大鼠心脏低灌复灌实验和乳鼠心肌细胞缺氧/复氧损伤（H/R）实验等模型,以血清CK、LDH、T-SOD、MDA等为指标,研究TG6对心肌缺血再灌注损伤的保护作用。结果在整体大鼠心肌缺血再灌注损伤实验中,TG6显著减少I/R损伤后心肌梗死面积,减少血清中CK活力和MDA含量,减少LDH活力,增加T-SOD活力;在离体大鼠心脏低灌复灌实验中,TG6显著增加低灌复灌后心肌冠脉流量,减少心肌组织中MDA含量和CK、LDH外漏,提高心肌组织中T-SOD活力;在乳鼠心肌细胞H/R损伤实验中,TG6对正常生长条件下的细胞没有明显影响,提高Na2S2O4制备的心肌细胞H/R模型下细胞的存活率、降低细胞CK的释放率及细胞[Ca^2＋]i的含量。结论 TG6对心肌I/R损伤有一定的保护作用。     

SM-20550, a new Na+/H+ exchange inhibitor and its cardioprotective effect in ischemic/reperfused isolated rat hearts by preventing Ca2+-overload

We investigated the effect of a newly synthesized compound, SM-20550 [N-(aminoiminomethyl)-1,4-dimethyl-1H-indole-2-carboxamide methanesulfonic acid] on Na+/H+ or Na+/Ca2+ exchange activity in rat cardiomyocytes, and on radioligand binding with several channels or receptors in membrane preparations, and ischemia/reperfusion injury in isolated perfused rat hearts. In myocytes, SM-20550 concentration-dependently inhibited the recovery from acidosis induced by an NH4Cl prepulse in HCO3(-)-free solution. Its IC50 was 10(-8) M, which was 10 times lower than that of ethylisopropyl amiloride (EIPA). SM-20550 (10(-6) M) did not affect the Na+-dependent Ca2+ influx (Na+/Ca2+ exchange activity) in cardiomyocytes. In the radioligand binding assay, SM-20550 did not have affinity for K+ channel, beta-adrenoceptor, adenosine, angiotensin, or endothelin receptors, and had low affinity for Na+ and Ca2+ channels and alpha-adrenoceptors, only at the concentrations of 10(-6)-10(-5) M. In perfused hearts exposed to 40 min of global ischemia and 20 min of reperfusion, SM-20550 (10(-8)-10(-7) M) significantly reduced the elevation of left ventricular end-diastolic pressure during reperfusion, improved the postischemic recovery of developed pressure, and prevented coronary perfusion pressure increase after reperfusion. Furthermore, SM-20550 reduced creatine phosphokinase release during reperfusion and prevented the abnormal gain of tissue Na+ and Ca2+ at the end of reperfusion. These results suggest that SM-20550 is a potent, highly specific Na+/H+ exchange inhibitor, which exerts a protective effect against myocardial ischemia/reperfusion injury. In addition, our data strongly support the hypothesis that Na+/H+ exchange plays an important role in the development of postischemic cardiac dysfunction, most likely by inducing Na+ and Ca2+ overload.     

六甲氧苄嗪对缺血再灌注损伤离体兔心的保护作用

六甲氧苄嗪(HMZ)是哌嗪类衍生物.该药灌注浓度为16μmol·L~1时能使缺血再灌注离体兔心肌磷酸肌酸激酶,谷草转氨酶释放量明显减少;并能提高超氧化物歧化酶的活性,降低脂质过氧化反应代谢产物丙二醛含量;预防缺血再灌注性心律失常的发生,结果提示HMZ对缺血再灌注损伤的心肌具有明显的保护作用,其机理可能与抗脂质过氧化反应有关