巯基化合物对离体大鼠心脏缺血再灌所致心律失常的保护作用

本文研究了半胱氨酸(Cys)及其结构类似物半胱胺(MEA),N-乙酰半胱氨酸(NAC)、胱胺(CSSC),γ-氨丙基甲基异硫脲(APMT),对离体大鼠Langendortff心脏缺血再灌所致心律失常的保护作用.给药(0.1,0.6,3,6μmol/min)10min,结扎LAD 10 min再灌5 min。结果表明含游离巯基的Cys,NAC,MEA在0.6和3.6 μmol/min时,与生理盐水对照组相比可显著降低室颤发生率(P<0.01～0.001),缩短室颤时程(P<0.01～0.001).CSSC和APMT未见明显保护作用。此外,Cys,NAC和MEA还可明显增加冠脉流量(P<0.01),CSSC和APMT则反而使冠脉流量降低。     

槲皮素对在体大鼠心肌缺血再灌性心律失常的保护作用

本文用在体Wistar大鼠心肌缺血再灌注模型,观察槲皮素对缺血再灌性心律失常的保护作用。在再灌前1min至再灌后2min静脉滴注槲皮素(0.5mmol/L,10ml/kg),可显著缩短心律失常的持续时间,降低室颤的发生率、再灌注区心肌组织中MDA的含量及XOD的活性,而对SOD具有明显的保护作用。结果提示槲皮素的抗心肌缺血再灌性心律失常作用可能与抑制心肌组织中OFR的形成和保护心肌组织中SOD或直接清除OFR有关。     

氨乙基异硫脲对在体家兔缺血/再灌流心肌损伤及自由基生成的影响(英文)

在家兔心脏冠状动脉结扎缺血/再灌流的损伤型模上,采用电子自旋共振(ESR)技术,直接测定整体家兔心肌缺血/再灌流早期自由基信号。自由基清除剂2-β-氨乙基异硫脲(AET)1.7 mg/kg,结扎前15 miniv,能使缺血30 min/再灌流2 min时,缺血心肌中自由基总浓度(10.6±4.1 nmol/g)明显低于对照组(18.0±2.1 nmol/g),而维拉帕米不能明显降低自由基生成量。AET还能减少再灌流期间脂质过氧化产物丙二醛生成量,降低血浆中CK,LDH的含量,改善ECG变化,从而使心肌梗塞的范围由对照组的31±4％降至12±2％。此外,AET可消除致死性室颤的发生。实验结果提示,自由基在缺血/再灌流损伤发生中起重要作用。AET对缩小心肌梗塞范围,消除室颤的发生具有良好的作用,因此可能是一类防治急性心肌梗塞及溶栓治疗或心脏手术后再灌流引起心律失常的有应用价值的新药。     

氨茶碱对三磷酸腺苷诱发兔窦房结电生理反应的抑制作用

目的　分析氨茶碱对三磷酸腺苷 (ATP)诱发兔窦房结电生理反应的抑制作用。方法　细胞内微电极技术记录兔离体窦房结细胞动作电位。结果　ATP( 0 3～ 3 0mmol/L)单次槽内注入给药 ,浓度依赖性减慢窦房结自发搏动速率 2 2 %～ 4 3% ,降低舒张期除极速率 4 2 9%～ 6 6 7% ,增大动作电位幅值 7 1%～ 9 2 % ,加快最大除极速率 32 0 %～ 75 5 % ,使动作电位复极 5 0 %和 90 %的时程 (APD50 和APD90 )缩短 7 1%～ 11 8%和7 3%～ 9 3%。P1受体阻断剂氨茶碱 ( 0 1mmol/L)显著拮抗ATP的作用 ,P2受体阻断剂反应蓝 2( 0 0 5mmol/L)则不影响ATP的作用。结论　ATP的上述电生理学效应可能通过P1受体介导     

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释放量明显低于对照组 (P <0 0 1) ,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 0 1)。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。     

药根碱对实验动物心肌缺血和复灌性损伤的保护作用

Jat(10mg/kg iv)对大鼠心肌缺血和复灌所致的心律失常均有对抗作用,可使心肌缺血和复灌期间心律失常的开始时间推迟、持续时间缩短,并使复灌期间室性心律失常的发生率和动物死亡率降低。耳静脉注射Jat(每次0.75mg/kg)还能使家兔冠脉结扎所致的心肌梗死范围缩小(n=6;P<0.01)。     

阿托伐他汀对不稳定型心绞痛患者血脂及C-反应蛋白的影响

ATPⅢ降脂治疗指南[1]指出,急性冠脉综合(ACS)的患者低密度脂蛋白(LDL)降至1.8mmol/L左右可明显减少临床事件,斑块可退化.应用他汀类药物可使心血管事件的发生率和死亡率下降约30%[2].本研究通过观察不稳定型心绞痛(UA)患者应用阿托伐他汀后血脂和血清C-反应蛋白水平的变化,了解其对UA患者C-反应蛋白水平和血脂的影响.     

利多卡因在搭桥术中抑制再灌注室颤研究

目的　研究冠脉搭桥手术中 ,开放升主动脉时注入 1 0 0mg利多卡因是否有利于避免再灌注室颤。方法　将 30例CAD患者随机分成 2组 :利多卡因组 (L组 )和对照组 (C组 )。L组 1 5名患者于升主动脉开放前 1分钟给予 1 0 0mg利多卡因 ,对照组给予 5ml的生理盐水 ,通过swan—ganz导管监测全组病人麻醉诱导后以及脱离体外循环后的血流动力学指标。结果　①L组的再灌注室颤的发生率 (1 7% )明显低于对照组 (5 8% )。 (P〈0 .0 5 )。②两组患者应用血管活性药物 ,没有明显差异。③与对照组比较利多卡因在脱离体外循环后心排量明显增加。 (P〈0 .0 1 )。结论　在开放升主动脉时注入利多卡因有利于防止再灌注室颤的发生     

制备大鼠离体心脏损伤模型的最佳缺血再灌注时间

目的 探索离体心脏最佳缺血再灌注(I/R)时间,增加制备可用于心肌保护药物的方法筛选的离体心脏I/R模型的成功率。方法 采用Langendorff离体心脏恒压灌流模式,缺血31 min后,分别于再灌5, 10, 20和30 min时测定心电图、左心室压力(LVP)、冠脉流量(CF)、左心室舒张末期压(LVEDP)和收缩末期压(LVESP);观察心律失常发生率,计算左心室发展压(LVDP)、收缩期舒张期左心室内最大上升/下降速率(±dp/dt_max)和心率(HR)。结果 离体心脏再灌后HR和CF低于停灌前,差异显著(P<0.05);停灌期间,LVEDP升高,心肌挛缩。再灌时90%心脏可成功自主复跳,100%复跳心脏出现心律失常(室速或室颤),持续约5~10 min。再灌后LVDP下降、左心室最大舒缩速度下降。结论 停灌31 min,再灌30 min可成功制备出用于药物筛选的离体心脏I/R损伤模型。     

急性冠脉综合症乳酸水平与预后的关系分析

目的:探讨急性冠脉综合症乳酸水平与预后的关系。方法:选取2013年6月~2014年7月本院重症监护室(ICU)收治的急性冠脉综合症患者50例,分别统计入住重症监护室后7d死亡者(死亡组)和生存者(生存组),给予两组患者动脉血乳酸水平动态监测,记录监测结果,探讨乳酸水平与急性冠脉综合症之间的关系。结果:入ICU后第1d、2d、3d、5d、7d生存组动脉血乳酸水平分别为(3.53±2.32)mmol/L、(3.79±1.5)mmol/L、(3.96±1.75)mmol/L、(4.16±1.21)mmol/L、(4.56±2.11)mmol/L,与存活组相比,差异有统计学意义(P0.05)。结论:动脉血乳酸水平是判断急性冠脉综合症患者预后的良好指标。     

Ischemia- and reperfusion-induced arrhythmias: beneficial actions of nifedipine

The effects of nifedipine against ischemia- and reperfusion-induced arrhythmias were investigated using anesthetized rats with transient coronary artery occlusion. Nifedipine (5 micrograms/kg i.v.) administered 10 min prior to occlusion significantly decreased the incidence of arrhythmias occurring during 20-min coronary occlusion. The incidence and duration of reperfusion-induced ventricular fibrillation and subsequent mortality following 5-min coronary occlusion were also significantly reduced by this intervention. However, administration of nifedipine 1 min prior to reperfusion afforded no protection against reperfusion arrhythmias. To investigate whether nifedipine possesses a true antiarrhythmic action or merely extends the ischemic duration prior to reperfusion resulting in maximal rhythm disturbances, reperfusion was initiated after 3, 5, 7, 10, 20, and 30 min of ischemia. Nifedipine reduced the incidence of reperfusion-induced ventricular fibrillation after all ischemic intervals, with no change in the time of peak vulnerability to reperfusion arrhythmias. Measurements of coronary flow with 153Gadolinium microspheres indicated that flow within ischemic tissue relative to that in normal tissue was significantly increased by nifedipine. Thus, administration of nifedipine prior to occlusion affords a protective effect against ischemia- and reperfusion-induced arrhythmias, and this action is not due to extension of the ischemic duration prior to reperfusion resulting in maximal rhythm disturbances.     

Inhibitory effects of pre-ischemic and post-ischemic treatment with FR 168888, a Na+/H+ exchange inhibitor, on reperfusion-induced ventricular arrhythmias in anesthetized rat

Effects of pre-ischemic and post-ischemic treatment with FR 168888 (5-hydroxymethyl-3-(pyrrol-1-yl) benzoylguanidine methanesulfonate), a Na+/H+ exchange inhibitor, on reperfusion-induced ventricular arrhythmias were examined in an ischemia/reperfusion model of anesthetized rat. FR 168888 (0.3 mg/kg) significantly reduced the incidence of ventricular fibrillation (VF) and mortality induced by reperfusion following 5-min coronary occlusion, when it was intravenously administered 5 min before coronary artery occlusion. Post-ischemic treatment with FR 168888 (0.3-10 mg/kg), i.e. given 3 min after the start of occlusion, reduced the incidence of VF and mortality. In order to examine the optimal time of administration, FR 168888 (3 mg/kg) was administered 1 or 3 min after the start of occlusion or immediately before reperfusion. There was no significant difference in the reduction of VF and mortality among the three post-ischemic treatment groups. FR 168888 (3 and 10 mg/kg) significantly increased the blood pressure during ischemia without affecting the heart rate. These results indicate that FR 168888 has antiarrhythmic effects on reperfusion-induced arrhythmias even administered after coronary occlusion.     

Effects of a novel cyclohexane dicarboximide derivative, ST-6, on reperfusion-induced arrhythmia in rats

The present study was designed to determine whether a novel cyclohexane dicarboximide derivative, ST-6, 2-[4-[4-(chlorophenyl)-4-hydroxy-1-piperidinyl]butyl]hexahydro-1H-isoindol-1,3(2H)-dione, prevents reperfusion-induced ventricular arrhythmias. Pentobarbital-anesthetized rats were subjected to left coronary artery occlusion for 4 min followed by 4-min reperfusion, and the incidence of their ventricular arrhythmias was examined. The coronary occlusion of control rats induced ventricular tachycardia and fibrillation, eventually leading to sudden death. The intravenous injection of 0.1 to 2 mg/kg ST-6 prior to the occlusion resulted in a dose-dependent suppression of the ventricular arrhythmias. The suppression of ventricular fibrillation was also observed on the intraperitoneal and intradoudenal administration of 2 to 10 mg/kg ST-6 15 min prior to coronary occlusion. Antiarrhythmic effects of this agent (0.5 mg/kg per min) were compared with those of other antiarrhythmic agents including lidocaine (0.1 mg/kg per min), sematilide (0.3 mg/kg per min), and diltiazem (0.5 mg/kg per min) by administrating the agents from 1 min after the coronary occlusion to the end of 4-min reperfusion. Antiarrhythmic effects of ST-6 were similar in degree to those of lidocaine and diltiazem, whereas no significant prevention by sematilide was seen. The results suggest that ST-6 may be capable of suppressing reperfusion-induced arrhythmias following oral or intravenous administration.     

Effects of KR-32570, a new sodium hydrogen exchanger inhibitor, on myocardial infarction and arrhythmias induced by ischemia and reperfusion

The present study was performed to evaluate the cardioprotective effects of [5-(2-methoxy-5-chloro-5-phenyl)furan-2-ylcarbonyl]guanidine (KR-32570) in rat and dog models of coronary artery occlusion and reperfusion. In addition, we sought to clarify the efficacy of KR-32570 on reperfusion-induced fatal ventricular arrhythmia. In anesthetized rats subjected to 45-min coronary occlusion and 90-min reperfusion, KR-32570 (i.v. bolus) dose-dependently reduced myocardial infarct size from 58.0% to 50.7%, 35.3%, 33.5% and 27.0% for 0.03, 0.1, 0.3 and 1.0 mg/kg, respectively (P<0.05). In anesthetized beagle dogs that underwent 1.2-h occlusion followed by 3.0-h reperfusion, KR-32570 (3 mg/kg, i.v. bolus) markedly decreased infarct size from 28.9% in vehicle-treated group to 8.0% (P<0.05), and reduced the reperfusion-induced release in creatine kinase isoenzyme MB, lactate dehydrogenase, Troponin-I and glutamic-oxaloacetic transaminase. KR-32570 dose-dependently decreased the incidence of premature ventricular contraction, ventricular tachycardia or ventricular fibrillation induced by ischemia and reperfusion in rats. Similar results were obtained in dogs with reperfusion-induced arrhythmia. In separate experiments to assess the effects of timing of treatment, KR-32570 given 10 min before or at reperfusion in rat models also significantly reduced the myocardial infarct size (40.9% and 46.1%, respectively) compared with vehicle-treated group. In all studies, KR-32570 caused no significant changes in any hemodynamic profiles. Taken together, these results indicate that KR-32570 significantly reduced the myocardial infarction and incidence of arrhythmias induced by ischemia and reperfusion in rats and dogs, without affecting hemodynamic profiles. Thus, it could be potentially useful in the prevention and treatment of myocardial injuries and lethal ventricular arrhythmias.     

The effects of L655,240, a selective thromboxane and prostaglandin endoperoxide antagonist, on ischemia- and reperfusion-induced cardiac arrhythmias

The purpose of this investigation was to provide a detailed analysis of the effects of the thromboxane antagonist L655,240 (0.3 mg/kg i.v.) on early ischemia- and reperfusion-induced arrhythmias in a canine model of coronary artery occlusion. In a dose that abolished the pulmonary response to U46619, L655,240 attenuated markedly the severity of those arrhythmias that resulted from reperfusion of the myocardium; survival from the combined occlusion-reperfusion insult was increased from 10% in control animals to 70% in dogs administered L655,240. Drug intervention did not significantly alter the total number of arrhythmias during the period of ischemia, but a detailed analysis of the different types of arrhythmia that occurred during this period showed that L655,240 significantly reduced those arrhythmias in phase 1a (0-10 min of occlusion) without affecting the later phase 1b arrhythmias. This was particularly shown in the marked reduction in the number of salvos (couplets and triplets) during this period. Neither those arrhythmias occurring later in the ischaemia period (phase 1b) nor the total number of single ectopics and salvos or the incidence and duration of ventricular tachycardia was modified by L655,240. These results reveal that thromboxane antagonism protects especially against reperfusion-induced ventricular fibrillation and against early (phase 1a) ischemia-induced arrhythmias, possibly implicating a role for thromboxane in the genesis of these cardiac rhythm disturbances.     

Effect of vasodilator drugs on coronary occlusion and reperfusion arrhythmias in anesthetized dogs

The effect of vasodilator drugs on the incidence of ventricular arrhythmias induced during 30 min of occlusion and 15 min of reperfusion of the left anterior descending coronary artery (LAD) was studied in 65 pentobarbital-anesthetized open-chest dogs. Intravenous administration of captopril (0.5 mg/kg), enalapril (0.5 mg/kg), felodipine (4 micrograms/kg), or ketanserin (0.1 mg/kg) 30 min before LAD occlusion reduced mean arterial blood pressure by 15.5 +/- 0.6% (mean +/- SEM). Nifedipine (5 micrograms/kg bolus + 1 microgram/kg min-1) infusion reduced mean arterial blood pressure by 24.8 +/- 1.8%. In none of the dogs was the diastolic blood pressure reduced below 70 mm Hg. During LAD occlusion, reduction in arterial blood pressure by these drugs was associated with a reduced incidence of ventricular premature depolarizations, ventricular tachycardia, and ventricular fibrillation (VF). During LAD reperfusion, the incidence of VF in saline-treated animals was 6/9, whereas for captopril it was 6/9, enalapril 1/9, felodipine 7/9, nifedipine 3/8, and ketanserin 3/9 animals. Thus, only enalapril significantly lowered the incidence of VF (p less than 0.05). The mechanism responsible for this antifibrillatory effect of enalapril is unknown. The muscle mass of the left ventricle supplied by the LAD distal to the site of occlusion in dogs which survived was similar to that of dogs which developed ventricular fibrillation.     

峨眉唐松草碱对离体大鼠心肌缺血再灌注损伤的保护作用

峨眉唐松草碱(methoxyadiantifoline 5μmol/L)显著降低大白鼠离体灌流心脏缺血再灌注损伤所致心室纤颤的发生率、延长窦性心律时间、减少心肌细胞中乳酸脱氢酶的释放及丙二醛的生成,显示其具有保护心肌及抑制脂质过氧化作用,效果与维拉帕米近似。     

Naloxone inhibits arrhythmias induced by coronary artery occlusion and reperfusion in anaesthetized dogs.

The intravenous administration of naloxone 2 min before coronary artery occlusion in anaesthetized dogs reduced the incidence and severity of cardiac arrhythmias during coronary occlusion (20 min) and reperfusion (120 min) in a dose-related manner. It also reduced the mortality. At a dose of 1 mg kg-1 (the maximum dose used in this study) naloxone abolished the appearance of the life threatening ventricular fibrillation (VF) and ventricular tachycardia (VT) and as a consequence all dogs in this group survived. The results suggest a possible involvement of endogenous opioid peptides in arrhythmogenesis during coronary occlusion and reperfusion in the dog.     

Inhibition of the Na(+)/H(+) exchanger attenuates phase 1b ischemic arrhythmias and reperfusion-induced ventricular fibrillation

The sodium-hydrogen exchanger-isotype 1 (NHE-1) plays a critical role in myocardial ischemia-reperfusion injury. While studies employing less selective sodium-hydrogen inhibitors have demonstrated antiarrhythmic activity, only one study has examined the in vivo efficacy of selective NHE-1 inhibition in a canine model of ischemia-reperfusion-induced arrhythmia. In the present study, the antiarrhythmic activity of Benzamide, N-(aminoiminomethyl)-4-?4-(2-furanylcarbonyl)-1-piperazinyl -3-(methy lsulfonyl), methanesulfonate (BIIB 513), a novel NHE-1 inhibitor, was examined. An in vivo canine model of myocardial ischemia-reperfusion injury in which 60 min of left anterior descending coronary artery (LAD) occlusion followed by 3 h of reperfusion was employed. BIIB 513 was infused either prior to ischemia or prior to reperfusion. Arrhythmias were quantified by single lead electrocardiogram. Infarct size, determined by triphenyltetrazolium staining, was expressed as a percent of the area-at-risk. In vivo, NHE-1 inhibition did not affect phase 1a arrhythmias, which occur within the first 10 min of occlusion, however, BIIB 513 significantly reduced the incidence of ischemia-induced phase 1b arrhythmias which occur between 10 and 30 min following occlusion and the incidence of reperfusion-induced ventricular fibrillation. Furthermore, NHE-1 inhibition significantly reduced infarct size, when the drug was administered either prior to ischemia or prior to reperfusion. NHE-1 inhibition selectively reduces both ischemia-induced phase 1b arrhythmias and reperfusion-induced ventricular fibrillation, and also markedly reduces myocardial infarct size when the drug is administered prior to ischemia or prior to reperfusion.