扎考必利对哇巴因诱发的成年大鼠心律失常的抑制作用

目的:观察内向整流钾通道激动剂扎考必利(zacopride)对哇巴因(ouabain)诱发的成年大鼠心律失常的影响,并探讨其电生理机制。方法:利用ouabain建立成年大鼠离体和在体心律失常模型,观察zacopride对各类心律失常的作用。应用全细胞膜片钳技术,观察zacopride对大鼠单个心室肌细胞内向整流钾电流(I_(K1))、静息膜电位(RMP)及延迟后除极(DADs)的影响。结果:浓度为1μmol/L的zacopride使ouabain诱发的离体心脏期前收缩个数、室速和室颤持续时间及发生率均显著降低(P0.05)。在麻醉大鼠,15μg/kg的zacopride使ouabain诱发的期前收缩个数、室速和室颤持续时间及发生率均显著降低(P0.05)。Ouabain使I_(K1)明显减小(P0.05),而0.1~10μmol/L zacopride可部分恢复甚至完全逆转ouabain对I_(K1)的抑制作用,其中1μmol/L为最大效应浓度。Ouabain使RMP减小(P0.05),应用zacopride(0.1~10μmol/L)后,RMP呈不同程度地增大,zacopride在1μmol/L时达最大效应浓度,使RMP增大至接近正常水平。1μmol/L的zacopride可有效抑制ouabain诱发的成年大鼠心室肌细胞DADs,使其发生率由91.67%下降至12.50%(P0.05);在灌流液中加入1μmol/L BaCl_2后,DADs再次出现。结论:内向整流钾通道激动剂zacopride对ouabain诱发的成年大鼠室性心律失常具有明显抑制作用,其机制与zacopride适度增强I_(K1)、使RMP负值增大并抑制DADs有关。     

Zacopride增强心肌内向整流钾电流(I_(K1))发挥抗心律失常效应

目的:探讨zacopride对乌头碱、氯化钡药物性心律失常模型的影响和增强心肌内向整流钾电流(IK1)与其抗心律失常的关系。方法:应用全细胞膜片钳技术观测zacopride对大鼠心室肌细胞膜主要离子流及静息膜电位(RMP)、动作电位(AP)和乌头碱所致延迟后除极(DAD)及触发活动(TA)的影响。并观察zacopride对乌头碱(30μg/kg,iv)和氯化钡(4 mg/kg,iv)2种药物性心律失常的影响。结果:0.1-10.0μmol/L zacopride可浓度依赖性激活大鼠心室肌IK1(P0.01),而对INa、Ito、ICa-L等影响动作电位的主要离子流均无显著影响(P0.05);使心室肌细胞膜超极化,动作电位时程(APD)缩短。1.0μmol/L为其最大效应浓度,使IK1内向电流部分(-100mV)增大33.8%,外向电流部分(-60 mV)增大32.4%;RMP由(-81.3±0.9)mV增大至(-87.5±1.7)mV,APD90由(32.48±2.70)ms缩短至(25.61±3.97)ms(P0.01),并有效消除乌头碱所致延迟后除极(DAD)和触发活动(TA)。对于乌头碱、氯化钡所致心律失常,15μg/kg zacopride可使2种心律失常持续时间分别由(57.58±3.21)min、(49.31±2.46)min缩短至(38.25±2.59)min和(30.94±1.73)min(P0.01)。结论:Zacopride对乌头碱、氯化钡药物性心律失常的抑制作用是由其激活心肌细胞IK1进而增大静息膜电位介导的。增强心室肌IK1可能成为抗心律失常的新机制。     

山莨菪碱对兔缺血再灌注心室肌细胞钠离子通道电流的影响

目的:建立兔心肌缺血再灌注动物模型,研究山莨菪碱对兔在体缺血再灌注后心室肌细胞钠离子通道电流(INa)的影响,探讨山莨菪碱抗再灌注心律失常的细胞学离子机制。方法:45只新西兰大耳白兔随机分为3组:缺血再灌注动物模型组(I/R组,结扎冠脉左前降支30min后再开放120min);山莨菪碱治疗组(Ani+I/R组,手术前1min给予动物耳缘静脉注射山莨菪碱5mg/kg);假手术对照组(只开胸不结扎血管)。观察缺血再灌注期间室性心律失常(室早、室速和室颤)的发生率及持续时间。采用酶解的方法分离缺血部位心室肌外膜单个心室肌细胞,应用全细胞膜片钳技术记录INa。结果:(1)心律失常发生率:与I/R组比较,Ani+I/R组兔室速、室颤发生率及持续时间明显下降,其心律失常的评分明显低于I/R组(2.6±0.7vs3.6±0.8,P0.05)。对照组、I/R组和Ani+I/R组INa电流密度峰值(-30mV)分别为-42.78±5.48(n=16)、-22.46±5.32(n=12)和-38.89±5.24pA/pF(n=13),I/R组明显低于对照组(P0.01),Ani+I/R组明显高于I/R组(P0.01)。结论:山莨菪碱可降低心肌缺血再灌注期间心律失常的发生率。心肌缺血再灌注后,INa明显下降,山莨菪碱预处理可使下降的INa上调,逆转电重构,可能为山莨菪碱降低再灌注心律失常发生率的细胞学离子机制。     

一氧化氮对缺血再灌注豚鼠左心室流出道自律性电活动的影响

目的:研究一氧化氮(NO)对豚鼠左心室流出道自发电活动的影响及其对缺血/再灌注(I/R)时自发电活动改变的影响。方法:采用标准玻璃微电极细胞内电位记录技术观测外源性NO供体硝普钠(SNP)对豚鼠左心室流出道自发慢反应电位的影响及其对I/R时该电位改变的影响。结果:1、10、100μmol/L SNP呈浓度依赖性地导致4相自动除极速度(VDD)和自发放电频率(RPF)明显增加,但1 000μmol/L SNP的效应不明显。SNP呈浓度依赖性地导致最大舒张电位(MDP)绝对值和动作电位幅度(APA)增大,0相最大除极速度(Vmax)加快,复极50%和90%时间(APD50和APD90)缩短。缺血10 min组VDD和RPF明显减慢,APA和Vmax明显增大,APD50和APD90明显延长。与缺血10 min组相比,再灌注10 min组VDD和RPF明显加快,且常出现节律不齐,MDP绝对值和APA明显减小,APD50和APD90明显缩短。1、10、100μmol/L SNP再灌注时可明显改善缺血造成的VDD和RPF减慢以及再灌注造成的节律不齐,1 000μmol/L SNP的上述效应不明显。各浓度SNP再灌注时均可使缺血造成的APA和APD的改变恢复至对照组水平。结论:SNP可呈浓度依赖性地增加左心室流出道的自律性,并可明显改善I/R导致的自发慢反应电位的改变。     

不同预处理后缺血再灌注损伤大鼠心肌αB晶状体蛋白的变化

目的 研究3种不同预处理对在体大鼠缺血再灌注心肌的保护作用及αB晶状体蛋白在不同预处理心肌细胞缺血再灌注损伤中的变化.方法 24只SD大鼠按完全随机法分成4组,每组6只,分别为缺血再灌注组、缺血预处理组、腺苷预处理组、远程预处理组.建立大鼠在体缺血再灌注损伤模型,观察各组缺血再灌注前后心功能变化,并检测冉灌注末血清肌钙蛋白T(cTnT)、丙二醛(MDA)、超氧化物歧化酶(SOD)的变化以及心肌组织αB品状体蛋白的表达.结果 心肌缺血再灌注120 min后,与缺血再灌注组比较,其余3组左心室室内压最大上升和下降速率(±dp/dt_(max))均明显升高(均P<0.05).缺血预处理组、腺苷预处理组、远程预处理组血清cTnT含量均低于缺血再灌注组[(12.898±2.887)、(5.049±4.387)、(7.049±4.387)μg/L比(22.902±3.146)μg/L,均P<0.05];MDA含量也均低于缺血再灌注组[(10.648±3.635)、(11.736±8.903)、(9.834±6.128)μmol/L比(16.083±10.423)μmol/L,均P<0.05];SOD含量均高于缺血再灌注组[(82.808±22.407)、(162.266±54.128)、(102.266±34.134)U/ml比(76.757±39.446)U/ml,均P<0.05].腺苷预处理组SOD含量高于缺血预处理组和远程预处理组;cTnT含量则低于缺血预处理组(均P<0.05).与缺血再灌注组比较,其余3组αB晶状体蛋白表达均显著增高(均P<0.05).结论 腺苷预处理、远程预处理均可以模拟缺血预处理的心肌保护作用.3种预处理可能通过上调αB晶状体蛋白表达从而减轻在体大鼠心肌缺血再灌注损伤.     

低浓度11,12-EET预干预对大鼠心肌缺血/再灌注损伤的影响

目的 :观察外源性低浓度 11,12 -EET预干预对大鼠在体心肌缺血 /再灌注损伤的影响。方法 :雄性Wistar大鼠 ,开胸 ,结扎和松开冠状动脉左前降支 ,复制心肌缺血 /再灌注模型 ;采用缺血 5min/再灌注 5min两次造成缺血预处置。实验分 3组 :对照组 ;缺血预处置组 ;外源性 11,12 -EET预干预组。每组再分为A、B 2小组 :A组动物心肌缺血 10min/再灌注 10min ,主要观察缺血 /再灌注各时程之心律失常 ;B组动物缺血 6 0min/再灌注 30min ,主要观察缺血期心律失常、心功能的变化及再灌注后心肌梗死范围。结果 :缺血预处置和 11,12 -EET(6 2 4× 10 -8mol/L)预干预均可减轻缺血 /再灌注心律失常及心功能的变化 ,降低心肌梗死范围。结论 :11,12 -EET预干预具有类缺血预处置样的心肌保护作用     

脂联素对大鼠缺血再灌注心肌缝隙连接蛋白43表达的影响

目的: 观察脂联素(APN)对大鼠缺血再灌注心肌缝隙连接蛋白43(Cx43)表达的影响,进一步探讨其抗心律失常的可能机制。方法: 将48只雄性Wistar大鼠随机分成:(1)假手术 (SM)组;(2)缺血再灌注(I/R)组:结扎冠状动脉左前降支,30 min后松开结扎线,再灌注120 min;(3)脂联素+缺血再灌注组1(I/R+APN1):先阻断血流30 min,于再灌注120 min开始时给予3.5 μg/kg APN;(4)脂联素+缺血再灌注组2(I/R+APN2):缺血前10 min给予3.5 μg/kg APN,余同I/R组。观察各组心律失常的发生情况;应用RT-PCR观察各组心室肌细胞 Cx43 基因表达;用免疫组织化学方法观察Cx43分布的变化;应用硫代巴比妥酸(TBA)法和黄嘌呤氧化酶法测各组动物血清中丙二醛(MDA)的含量和超氧化物歧化酶(SOD)的活性;用RT-PCR及Western blotting法分析内皮型一氧化氮合酶(eNOS)mRNA及蛋白的表达,用电镜观察各组心室肌超微结构的改变。结果: (1)I/R组与SM组比较,心律失常评分和血清MDA含量显著增高(P<0.01),SOD活性降低(P<0.01);心室肌Cx43表达明显减少,差异有统计学意义(P<0.01),Cx43分布紊乱,失去正常的规律性;心肌细胞超微结构有明显损伤;心室肌eNOS mRNA及蛋白的表达明显降低,差异有统计学意义(P<0.01)。(2)无论缺血前还是缺血后使用脂联素处理,与I/R组相比,心律失常评分显著降低(P<0.01);Cx43及eNOS表达增高(P<0.01),Cx43分布紊乱的程度减轻;心肌细胞超微结构损伤明显改善。结论: APN可能通过氧化应激调节Cx43的功能,从而发挥抗缺血/再灌注心律失常的作用。     

丹参酮ⅡA磺酸钠对家兔缺血预处理心肌保护作用的影响

目的观察丹参酮ⅡA磺酸钠对家兔缺血预处理心肌保护作用及血浆和心肌组织NO代谢产物含量的影响。方法家兔24只 ,随机分为心肌缺血再灌注组 (IR ,n=8)、缺血预处理组 (IPC,n=8)和丹参酮ⅡA磺酸钠联合缺血预处理组 (DS-201 IPC,n=8) ;TTC染色测定梗塞面积 ;HE染色病理组织学观察。采用硝酸还原酶法检测缺血前、缺血后30min和再灌注30min三个时点血浆及心肌组织NO代谢物含量。结果 (1)TTC染色称重结果显示 ,IPC组心肌梗死面积 (梗死区重量/缺血区重量为9.54±5.79)明显小于IR组 (梗死区重量/缺血区重量为35.48±3.84Δ ,P<0.05) ,DS201 IPC组心肌梗死面积 (梗死区重量/缺血区重量为5.66±1.6)明显小于IPC组心肌梗死面积 (P<0.05)。病理学检测显示 ,与IR组相比 ,IPC组组织损伤程度明显减轻。与IPC组相比 ,DS201 IPC组组织损伤程度明显减轻。 (2)缺血30min和再灌注30minIR组血浆NO代谢产物[缺血30min(11.2±3.9)μmol/L,再灌注30min(11.6±5.6)μmol/L]和心肌组织NO代谢产物[再灌注30min末(23.0±5.3)μmol/mg]显著低于缺血前[血浆NO代谢产物为(28.5±6.8)μmol/L,心肌组织NO代谢产物为(49±18.3)μmol/mg](P<0.05) ;缺血30min和再灌注30minIPC组血浆NO代谢产物[缺血30min(19.5±2.5)μmol/L,再灌注30min(1     

Na^＋—H^＋交换阻滞剂对离体鼠心缺血后再灌注损伤的保护作用

为评价Na~+-H~+交换阻滞剂对缺血再灌注损伤的保护作用,在改良的Langendoff装置上采取主动脉逆灌方法,用成年Wistar大鼠的离体鼠心完全停灌60min,然后100%再灌注30min造成再灌注损伤模型。阿米洛利(0.2、20、100μmol/L)和呋喃苯胺酸(10μmol/L)为药物保护组及不加药物的对照组。结果显示:阿米洛利和呋喃苯胺酸对再灌注时心肌收缩力、冠脉流量的恢复及抑制再灌注心律失常的发生有明显的作用,阿米洛利抗心律失常的效果呈明显的剂量依赖性。因此提示具Na~+-H~+交换阻断作用的阿米洛利和呋喃苯胺酸具明显的抗再灌注损伤的作用。     

低浓度11,12-EET预干预对大鼠心肌缺血/再灌注损伤的影响

目的:观察外源性低浓度 11,12-EET预干预对大鼠在体心肌缺血/再灌注损伤的影响。方法:雄性Wistar大鼠,开胸,结扎和松开冠状动脉左前降支,复制心肌缺血/再灌注模型;采用缺血 5min/再灌注 5min两次造成缺血预处置。实验分 3组:对照组;缺血预处置组;外源性 11,12-EET预干预组。每组再分为A、B 2小组:A组动物心肌缺血 10min/再灌注 10min,主要观察缺血/再灌注各时程之心律失常;B组动物缺血 6 0min/再灌注 30min,主要观察缺血期心律失常、心功能的变化及再灌注后心肌梗死范围。结果:缺血预处置和 11,12-EET(6 2 4× 10^-8mol/L)预干预均可减轻缺血/再灌注心律失常及心功能的变化,降低心肌梗死范围。结论:11,12-EET预干预具有类缺血预处置样的心肌保护作用.     

Action of regulators of peripheral cholinergic processes on development of early arrhythmia in myocardial ischemic rats

Occlusion of the left coronary artery in rats provoked ventricular tachycardia (VT) and ventricular fibrillation (VF) within the first 30 min of ischemia leading to death in 20% animals. Methacin (i.v., 100 micrograms/kg) significantly prolonged VT and VF without effects on the survival. Acetylcholine (i.v., 10 micrograms/kg/min) had no influence on VT frequency and severity but prevented VF. Rats from this group survived. The same effect was observed for neostigmine (i.v., 25 micrograms/kg). Nicotine (i.v., 2.5 micrograms/kg/min) prolonged VT episode duration but did not change frequency and severity of VF and survival. Ganglioblockers hexametony and azametony (i.v., both in a dose 500 micrograms/kg) significantly attenuated VT, prevented VF and death of the animals. Thus, cholinotropic drugs may have both antiarrhythmic and proarrhythmogenic effects in early arrhythmias induced by ischemia.     

Antiarrhythmic and arrhythmogenic effects of L-carnitine in ischemia and reperfusion

Isolated rat hearts were subjected to 30-min coronary artery occlusion followed by 120-min reperfusion. The hearts (n=8–12) were perfused with Krebs-Henseleit solution enriched with L-carnitine (0.5, 2.5 and 5 mM) for 10 min before and after ischemia or reperfusion and for the whole period of ischemia and reperfusion. Two-hour perfusion with L-carnitine during ischemia/reperfusion markedly (p<0.05) and dose-dependently decreased the incidence of ventricular tachycardia (VT, maximum 65%). The incidence of reperfusion ventricular fibrillation (VF) also decreased from 63% (control) to 17% in hearts perfused with 5 mM L-carnitine, as reflected by a significant (p<0.05) decline in VF duration from 218±99 sec in control to 19±19 sec. Perfusion of etomoxir (palmitoylcarnitinetransferase-1 inhibitor) along with L-carnitine reversed the antiarrhythmogenic action of L-carnitine. Interestingly, short time preischemic administration of L-carnitine produced a concentration-dependent arrhythmogenic effects on both ischemia and reperfusion-induced arrhythmias. These results show that L-carnitine produced a protective effect against reperfusion arrhythmias only when it was perfused for the whole period of the experiment. This protective action was reversed by concomitant use of etomoxir, suggesting that the efficacy of L-carnitine is due to its mitochondrial action but cannot be solely attributed to increased fatty acid oxidation. Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 146, No. 8, pp. 175–178, August, 2008     

Increased vulnerability to ischemia/reperfusion-induced ventricular tachyarrhythmias by pre-ischemic inhibition of nitric oxide synthase in isolated rat hearts.

INTRODUCTION: The relationship between vulnerability to reperfusion-induced ventricular tachyarrhythmias, such as ventricular tachycardia (VT) and fibrillation (VF), and the endogenous activity of nitric oxide synthase (NOS) has not been well documented. The objective of the present study was to clarify whether the vulnerability to reperfusion-induced VT/VF changes with preishemic, sustained inhibition of NOS. METHODS: The experiments were performed using Langendorff-perfused isolated rat hearts, in which left ventricular pressure (LVP) and left ventricular cardiomyograms (LVCMGs) were measured. RESULTS: A pre-ischemic, sustained inhibition of NOS resulted in an increased vulnerability to reperfusion-induced VT/VF, and the increase was markedly attenuated by co-treatment with L-arginine or by post-ischemic treatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of tetrahydrobiopterin (BH(4)) synthesis. We then tried to elucidate whether nitric oxide (NO) and superoxide were produced during reperfusion, and ATP-sensitive potassium channels (K(ATP)), especially mitochondrial ATP-sensitive potassium channels (mitoK(ATP)), are involved in the increased vulnerability. Post-ischemic inhibition of NOS and treatment with a NO scavenger attenuated the increased vulnerability to reperfusion-induced VT/VF, but post-ischemic treatment with a superoxide scavenger did not. In addition, post-ischemic treatment with S-nitroso-N-acetyl-DL-penicillamine (SNAP), a NO donor, or with diazoxide, a selective opener of mitoK(ATP), increased the VT/VF duration during reperfusion. The increased vulnerability to VT/VF was attenuated by the treatment with a selective mitoK(ATP) blocker. CONCLUSION: The results suggest that a pre-ischemic, sustained inhibition of NOS increases the vulnerability to reperfusion-induced VT/VF, and the NO-mitoK(ATP) pathway is one of the possible factors contributing to the increased vulnerability to VT/VF.     

心肌内向整流钾通道激动剂抑制异丙肾上腺素所致大鼠心室重构

目的:观察和探讨内向整流钾通道(Ⅰ_(K1))激动剂盐酸扎考必利(zacopride,Zac)对异丙肾上腺素(isoproterenol,Iso)所致心室重构的影响及作用机制。方法:SD大鼠随机分为正常对照组、Iso模型组、Zac干预组、Zac+氯喹干预组和卡托普利阳性对照组。腹腔注射异丙肾上腺素3 mg/kg,每天1次,连续给药10 d,观测各组全心质量/体质量比和左心室质量/体质量比。用全细胞膜片钳技术检测大鼠心室肌细胞电压门控钙电流(Ⅰ_(Ca-L))、静息膜电位(RMP)及动作电位时程(APD)的变化。选用新生1~3 d的SD乳鼠,用0.08%胰蛋白酶和0.04%Ⅱ型胶原酶消化心脏组织,经差速贴壁法和5-溴脱氧尿嘧啶核苷纯化心肌细胞后随机分成正常对照组、Iso模型组、Zac干预组、Zac+BaCl_2干预组和Zac+氯喹干预组,培养24 h后用激光共聚焦显微镜检测心肌细胞内游离钙离子浓度。结果:Iso模型组与正常对照组比较,全心肥厚指数、左心室肥厚指数明显增加,膜片钳结果提示RMP减小APD明显延长;Zac干预组明显抑制心肌肥大,并增大RMP,缩短APD。同时应用低剂量Ⅰ_(K1)抑制剂氯喹可明显抑制Zac的抗心室重构作用,并逆转Zac对RMP和APD影响。在乳鼠心肌细胞,Iso可使细胞表面积增大,细胞内[Ca~(2+)]_i增高;Zac干预后细胞形态恢复至正常或接近正常水平,并显著减轻钙超载。Ⅰ_(K1)阻断剂BaCl_2和氯喹可阻断Zac的效应。结论:Ⅰ_(K1)选择性激动剂Zac明显抑制异丙肾上腺素所致的心室重构,其机制可能为增强Ⅰ_(K1),进而增大RMP,缩短APD,从而阻断心肌细胞内钙超载依赖的信号通路。     

Endogenous cannabinoids improve myocardial resistance to arrhythmogenic effects of coronary occlusion and reperfusion: a possible mechanism

Stimulation of cannabinoid receptors with endogenous cannabinoid anandamide and its enzyme-resistant analogue R-(+)-methanandamide improved cardiac resistance to arrhythmias induced by coronary occlusion and reperfusion. This antiarrhythmic effect was not associated with activation of NO synthase, since pretreatment with NG-nitro-L-arginine methyl ester had no effect on the incidence of ischemia/reperfusion-induced arrhythmias. Blockade of ATP-dependent K+ channels with glybenclamide did not abolish the antiarrhythmic effect of R-(+)-methanandamide. Antiarrhythmic activity of endogenous cannabinoids is probably associated with their direct effects on the myocardium.     

Involvement of Ca(2+) in antiarrhythmic effect of ischemic preconditioning in isolated rat heart

We investigated the relationship between the effects of ischemic preconditioning (IPC) and Ca(2+) preconditioning (CPC) on reperfusion-induced arrhythmias. In the control group (noPC), Langendorff-perfused rat hearts were subjected to 5-min zero-flow global ischemia (I) followed by 15-min reperfusion (I/R). In ischemic preconditioning groups (IPC), the hearts were subjected to three cycles of 3-min global ischemia and 5-min reperfusion. In the CPC group, the hearts were exposed to three cycles of 3-min perfusion of higher Ca(2+) (2.3 mmol/l Ca(2+)) followed by 5-min perfusion of normal 1.3 mmol/l Ca(2+), and the hearts were then subjected to I/R. Verapamil was administered in several hearts of the IPC group (VR+IPC). Ventricular arrhythmias upon reperfusion were less frequently seen in the IPC and CPC groups than in the noPC and VR+IPC groups. IPC and CPC could attenuate conduction delay and enhance shortening of the monophasic action potential duration during ischemia. The ventricular fibrillation threshold measured at 1-min reperfusion was significantly higher in the IPC and CPC groups than in the noPC and VR+IPC groups. Verapamil completely abolished the salutary effects of IPC. These results demonstrate that Ca(2+) plays an important role in the antiarrhythmic effect of IPC during reperfusion.     

缺血后处理对抗大鼠离体心脏缺血再灌注损伤及其作用机制

目的： 研究缺血后处理（postconditioning）对抗大鼠离体心脏缺血再灌注损伤及其作用机制。方法：采用SD大鼠心肌缺血/再灌注模型，并于再灌注一开始即给予3次全心停灌30 s，再灌30 s处理作为缺血后预处理。记录心肌收缩功能指标，以Even’s blue-TTC法监测心肌梗死范围，并对心律失常严重程度进行定量分析。结果：缺血后处理组左室峰压（LVSP）、最大左室收缩速率（+dp/dt_max）以及心率明显高于缺血对照组。缺血后处理可明显缩小心肌梗死范围（22.97%±3.96% vs 缺血对照组 44.30%±13.61%，P<0.01）。观察复灌10 min时心律失常评分发现，缺血后处理组明显低于缺血对照组。缺血后处理组和缺血预处理组具有类似的心肌保护作用。5-HD组LVSP和+dp/dt_max低于缺血后处理组，心律失常评分增高，心肌梗死范围扩大。结论: 缺血后处理对大鼠缺血再灌注损伤具有心脏保护作用，其作用机制可能是部分通过激活线粒体ATP依赖性钾离子(mitoK_ATP)通道起作用。     

ATP敏感性钾通道在硫化氢抑制高糖引起的心肌细胞损伤中的作用

目的:研究ATP敏感性钾通道(KATP通道)在硫化氢(H2S)抑制高糖引起心肌损伤中的作用。方法:应用Western blot法检测心肌细胞KATP通道蛋白的表达水平;CCK-8试剂盒测定心肌细胞存活率;Hoechst33258染色测定凋亡细胞数量的变化;JC-1染色法测定线粒体膜电位(MMP)。结果:应用高糖(35 mmol/L葡萄糖)处理H9c2细胞1~24 h,其中6 h、9 h、12 h和24 h均能明显下调KATP通道蛋白的水平,12 h和24 h KATP水平降至最低。在HG处理心肌细胞12 h前,应用400μmol/L硫氢化钠(Na HS,为H2S的供体)预处理30 min明显抑制高糖对KATP通道蛋白表达的下调作用。100μmol/L线粒体KATP通道开放剂二氮嗪和50μmol/L非选择性KATP通道开放剂吡拉地尔(Pin)及Na HS预处理均显著抑制高糖引起的心肌细胞损伤,使细胞存活率升高,凋亡细胞数量及MMP丢失减少。相反,100μmol/L线粒体KATP通道阻断剂5-羟基癸酸和1 mmol/L非选择性KATP通道阻断剂格列本脲均能明显阻断上述Na HS的心肌细胞保护作用。结论:KATP通道介导了H2S对高糖引起的心肌细胞损伤的抑制作用。