阿托伐他汀在大鼠急性心肌缺血再灌注中的保护作用及机制

目的探讨短期阿托伐他汀在大鼠急性心肌缺血再灌注中的保护作用及可能机制。方法将健康雄性SD大鼠49只随机分四组:假手术组(n=7,生理盐水2ml/d)、缺血再灌组(n=14,生理盐2ml/d))、阿托伐他汀组(n=14,阿托伐他汀20mg·kg-1·d-1)、阿托伐他汀+L-硝基精氨酸甲酯组(n=14,阿托伐他汀20mg·kg-1·d-1、L-NAME15mg/kg)。灌喂3d后制作大鼠在体心肌I/R模型。L-硝基精氨酸甲酯(L-NAME)于缺血前15min静脉注射。再灌注后,测定血清心肌酶及一氧化氮(NO),心肌组织丙二醛(MDA)及总超氧化物歧化酶(TSOD);Evansblue、TTC双重染色后,用计算机图像分析软件计算梗死面积。结果阿托伐他汀组与缺血再灌注组比,心梗面积减小;LDH、CK降低,NO增加;TSOD升高、MDA降低(P<0.01)。阿托伐他汀+L-硝基精氨酸甲酯组较阿托伐他汀组心梗面积增大;LDH、CK升高,NO降低;TSOD降低、MDA升高(P<0.01),与缺血再灌组相似(P>0.05)。结论阿托伐他汀能明显减轻心肌I/R损伤;其作用机制与增加NO含量、提高心肌组织TSOD活性、降低MDA含量有关。     

阿托伐他汀通过激活Nrf2通路对抗大鼠缺血再灌注心肌氧化应激损伤和凋亡

目的:观察阿托伐他汀预处理对大鼠心肌缺血-再灌注损伤(MIRI)超氧化物歧化酶(SOD)和丙二醛(MDA)浓度、心肌细胞内Caspase-3和Nrf2表达的影响,探讨阿托伐他汀的心肌保护作用机制。方法:将40只雄性SD大鼠随机等分为4组:假手术组(A组)、缺血再灌注组(B组)、阿托伐他汀标准剂量预处理组(C组)和阿托伐他汀强化剂量预处理组(D组)。灌胃7d后,第8天制作大鼠在体心肌MIRI模型,结扎左冠状动脉前降支30min,再灌注120min后,用比色法检测心肌中MDA和SOD浓度,Western blot检测活化Caspase-3和Nrf2的表达。结果:与B组比较,C组SOD浓度明显增加(P0.05),MDA浓度明显减少(P0.05),Caspase-3表达明显减少(P0.05),Nrf2表达明显增多(P0.05);与C组比较,D组SOD浓度、Nrf2表达增加更为明显(P0.05),MDA、Caspase-3表达减少更为明显(P0.05)。结论:阿托伐他汀预处理明显增强抗氧化酶活性,抑制指质过氧化,减少细胞凋亡,减轻MIRI损伤,且呈剂量依赖性,表现较强的心肌保护作用,其机制可能与增加心肌Nrf2表达有关。     

阿托伐他汀通过抑制NF-κB对抗大鼠缺血再灌注心肌炎症反应和凋亡的机制

目的:观察阿托伐他汀预处理对大鼠心肌缺血再灌注损伤(MIRI)肿瘤坏死因子(TNF)和白细胞介素-l(IL-1)、心肌细胞内Caspases-3和NF-κB表达的影响,探讨阿托伐他汀的心肌保护作用机制。方法:将40只雄性SD大鼠随机等分为4组:假手术组(A组,0.9%氯化钠溶液5ml/d),缺血再灌注组(B组,0.9%氯化钠溶液5ml/d)、阿托伐他汀标准剂量预处理组(C组,阿托伐他汀20mg/d)和阿托伐他汀强化剂量预处理组(D组,阿托伐他汀40mg/d)。灌胃7d后,第8天制作大鼠在体心肌I/R模型,结扎左冠状动脉前降支30min,再灌注120min后,用ELISA法检测心肌中TNF-α和IL-1β水平,Western blot检测活化Caspase-3和NF-κB的表达。结果:与B组比较,C组TNF-α、IL-1β、Caspases-3、NF-κB水平均明显减少(均P0.05);与C组比较,D组TNF-α、IL-1β、Caspases-3及NF-κB表达减少更为明显(均P0.05)。结论:阿托伐他汀预处理明显抑制炎症反应,减少细胞凋亡,减轻MIRI损伤,呈现较强的心肌保护作用,其机制可能与抑制心肌NF-κB表达有关。     

阿托伐他汀对急性心肌梗死大鼠边缘带心肌IL-8表达与室性心律失常的影响

目的:探讨阿托伐他汀对急性心肌梗死后室性心律失常的抑制作用及机制。方法:45只雄性急性心肌梗死大鼠随机均分为高、低剂量阿托伐他汀组及急性心肌梗死组(每组15只)。另取10只大鼠作为假手术组。高、低剂量阿托伐他汀组每日分别给予阿托伐他汀10mg·kg-1·d-1、20mg·kg-1·d-1灌胃1周,假手术组和急性心肌梗死对照组不予治疗。第1周末以程序电刺激诱发各组大鼠室性心律失常后,假手术组取位于左心室游离壁心肌组织,心肌梗死各组取位于左心室梗死边缘带心肌组织检测白细胞介素(IL)-8表达。结果:急性心肌梗死组梗死边缘带IL-8表达水平及室性心律失常诱发率均高于假手术组(P0.01),低剂量阿托伐他汀组梗死边缘带IL-8表达水平及室性心律失常诱发率显著低于急性心肌梗死组(P0.05)。高剂量阿托伐他汀组梗死边缘带IL-8表达水平及室性心律失常诱发率显著低于低剂量组(P0.05)。结论:阿托伐他汀可能通过抑制IL-8过度表达来降低室性心律失常发生率,其作用呈剂量依赖性。     

氟伐他汀对心肌梗死大鼠左室重塑和功能的影响

目的探讨羟甲基戊二酰辅酶A(HMGCoA)还原酶抑制剂氟伐他汀对急性心肌梗死(AMI)大鼠左室结构和功能的影响。方法雌性SD大鼠AMI后6h随机分为AMI组和氟伐他汀组;另设假手术组。三组大鼠直接灌胃给药或自来水8周后行高频多普勒超声、血流动力学、心脏重塑指标及左心室心肌α、β肌球蛋白重链(α、βMHC)mRNA表达的测定。结果与假手术组相比,AMI组左室舒张末期内径(LVEDD)、左室舒张末期容积(LVEDV)、E峰、E峰减速度、E/A、左室舒张末压(LVEDP)、左、右心室心肌肥厚指数、非梗死区胶原容积分数(CVF)和βMHCmRNA均明显增加(P<0.01),左室短轴缩短率(FS)、射血分数(EF)和αMHCmRNA显著降低(P<0.01)。与AMI组相比,氟伐他汀组的LVEDD、LVEDV、E峰、E峰减速度、E/A、LVEDP、左、右心室心肌肥厚指数、CVF和βMHCmRNA均显著降低或减少(P<0.01),FS、EF和αMHCmRNA显著升高(P<0.01)。结论氟伐他汀能抑制大鼠AMI后左室重塑,改善血流动力学异常和左室功能。     

阿托伐他汀对肾血管性高血压大鼠心肌纤维化及CTGF表达的影响

目的探讨阿托伐他汀对肾性高血压大鼠心肌纤维化以及结缔组织生长因子(CTGF)表达的影响。方法建立肾性高血压大鼠模型,将实验大鼠24只随机分为3组,每组8只,对照组、高血压组、阿托伐他汀组。术后4周末开始用阿托伐他汀50mg/(kg.d)连续灌胃8周。测量大鼠尾动脉收缩压,检测心肌胶原浓度、心肌总胶原容积分数(t-CVF)以及免疫组化检测心肌CTGF的表达。结果高血压组尾动脉收缩压、心肌羟脯氨酸含量、t-CVF以及CTGF的表达显著高于对照组(P<0.01);阿托伐他汀组大鼠的心肌羟脯氨酸含量、t-CVF和CTGF的表达低于高血压组(P<0.01)。结论阿托伐他汀具有抑制心肌纤维化的作用,其机制可能与下调CTGF的表达有关。     

阿托伐他汀干预对糖尿病心肌梗死后大鼠左室重构和心功能的影响

目的我们的前期研究已经表明,结扎左冠状动脉前降支后,糖尿病大鼠的左心功能恶化及左室重构的速度均较非糖尿病大鼠显著;心肌梗死四周后,糖尿病大鼠心肌纤维化的程度明显高于非糖尿病大鼠。本研究旨在评价阿托伐他汀对糖尿病心肌梗死(AMI)后心力衰竭(HF)大鼠心室重构的干预效应。方法75只雄性SD大鼠经链脲霉素诱导糖尿病成功后随机分成三组,即:心肌梗死对照组(MI,n=30),阿托伐他汀(20mg.kg-1.d-1)干预组(A,n=30),及假手术组(S,n=15)。所有大鼠经腹腔内注射链脲霉素(STZ,65mg/kg)诱导糖尿病,10周后MI组和A组大鼠结扎左冠状动脉前降支建立AMI模型。干预组于术后24h直接灌胃法给药。干预4周后血流动力学测定,之后采血、处死大鼠、取出心脏,观察血脂水平、心脏/体重比值、病理组织形态,苦味酸-天狼猩红染色测定非梗死区Ⅰ型和Ⅲ型胶原含量及Ⅰ/Ⅲ型胶原比值,免疫组化分析非梗死区基质金属蛋白酶-2(MMP-2)及其抑制物TIMP-2蛋白表达,Western blot检测TGFβ1在非梗死区的蛋白表达。结果(1)各组间血脂水平差异无统计学意义;(2)干预组与对照组比较,心脏体重比值、非梗死区Ⅰ型和Ⅲ型胶原含量及Ⅰ/Ⅲ型胶原比值均降低,但仍高于假手术组;干预组较对照组MMP-2、TGFβ1表达及MMP-2/TIMP-2比值降低,TIMP-2表达增高;(3)血流动力学检测表明干预组较对照组左室最大压力、左室内压最大上升下降速率、平均动脉压增高,而左室最小压力、左室舒张末压力、舒张常数降低。结论糖尿病大鼠心肌梗死后,长时间(4周)应用阿托伐他汀治疗改善了左心重构和心功能。阿托伐他汀能够减轻非梗死区心肌间质胶原重构,其机制可能与下调MMP-2和TGFβ1的表达及MMP-2/TIMP-2比值,升高TIMP-2表达有关。     

阿托伐他汀逆转腹主动脉缩窄型高血压大鼠心肌重构的机制

目的 观察阿托伐他汀对腹主动脉缩窄型高血压大鼠血清血管紧张素(1-7)浓度及左心室肥厚心肌组织中p-ERK1/2表达水平的影响,探讨阿托伐他汀逆转心肌重构的可能机制.方法 50只SD雄性大鼠随机分为5组:假手术组、模型组、10 mg/(kg·d)阿托伐他汀组、30 mg/(kg·d)阿托伐他汀组及缬沙坦组,每组10只.术后第1天,将阿托伐他汀研磨成粉,溶于少量蒸馏水中制成悬液,采用灌胃法给药;假手术组和模型组大鼠均用等量生理盐水灌胃.每日上午定时一次,共4周.鼠尾容积法测定药物干预前及干预后2周、4周的血压变化.4周后处死大鼠,测定大鼠体重、左心室重量、左心室重量指数;HE染色检测心肌细胞平均直径;酶联免疫吸附法测定血清血管紧张素(1-7)浓度;免疫印迹法检测心肌p-ERK1/2蛋白表达水平.结果 30 mg/(kg·d)阿托伐他汀组和10 mg/(kg·d)阿托伐他汀组收缩压明显低于模型组(P<0.01),30 mg/(kg·d)阿托伐他汀组收缩压明显低于10mg/(kg·d)阿托伐他汀组(P<0.01),缬沙坦组收缩压明显低于30 mg/(kg·d)阿托伐他汀组和10 ms/(kg·d)阿托伐他汀组(P<0.01);假手术组、30 mg/(kg·d)阿托伐他汀组、10 mg/(kg·d)阿托伐他汀组及缬沙坦组左心室重量指数明显低于模型组(P<0.01),30 mg/(kg·d)阿托伐他汀组左心室重量指数明显低于10 mg/(kg·d)阿托伐他汀组(P<0.05);假手术组、30 mg/(kg·d)阿托伐他汀组及缬沙坦组心肌细胞平均直径明显低于模型组(P<0.01).10 mg(kg·d)阿托伐他汀组与模型组无差异(P>0.05);10 mg/(kg·d)阿托伐他汀组、30 mg/(kg·d)阿托伐他汀组及缬沙坦组血清Ang-(1-7)浓度显著高于模型组(P<0.01),30 mg/(kg·d)阿托伐他汀组及缬沙坦组血清Ang.(1-7)浓度明显高于10 mg/(kg·d)阿托伐他汀组(P<0.05);10 mg/(kg·d)阿托伐他汀组、30mg/(kg·d)阿托伐他汀组及缬沙坦组p-ERK1/2蛋白表达水平显著低于模型组(P<0.01),但高于假手术组.结论 阿托伐他汀对腹主动脉缩窄型高血压大鼠心肌重构具有逆转作用,其机制与降低压力负荷诱导的心肌肥厚组织中p-ERK1/2 蛋白表述水平有关.     

阿托伐他汀对慢性心力衰竭大鼠左室重构和功能的影响及可能的机制

目的探讨阿托伐他汀对异丙肾上腺素(ISO)诱导的慢性心力衰竭(CHF)大鼠左室重构和心功能的影响以及可能的机制。方法将ISO诱导的CHF大鼠随机分成ISO组与ISO 阿托伐他汀组,同时以正常大鼠为对照组。4周后行心动超声、血流动力学、血清细胞因子检查和心脏标本检测(左室质量／体质量)及RT-PCR 检测心肌基质金属蛋白酶-2(MMP-2)mRNA表达水平。结果 (1)与对照组比较,ISO组左室收缩末期内径(LVESD)、左室舒张末期内径(LVEDD)、左室舒张末压(LVEDP)及左室压力最大下降速率(dp／dtmin)明显升高,左室收缩末压(LVESP)、左室压力最大上升速率(dp／dtmax)及左室短轴缩短率(FS)则明显降低(P<0．01);而ISO 阿托伐他汀组,LVESD、LVEDD、LVEDP、dp／dtmin和LVESP、dp／dtmax及FS值则介于对照组与ISO组之间,且与ISO组比较, LVESD、LVEDD、LVEDP及dp／dtmin明显降低,而LVESP、dp／dtmax及FS则明显升高(P<0．05);左室后壁厚度在 ISO组和ISO 阿托伐他汀组没有明显的不同(P>0．05)。(2)与对照组相比,ISO组和ISO 阿托伐他汀组左室质量／体质量(LVW／BW)明显增大(P<0．01);但与ISO组比较,ISO 阿托伐他汀组LVW／BW降低(P<0．05)。 ISO组MMP-2 mRNA表达水平较对照组明显升高(P<0．01),而ISO 阿托伐他汀组较ISO组降低(P<0．05)。 (3)ISO组大鼠血清肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)水平均比正常对照组显著升高(P<0．01); 与ISO组比较,ISO 阿托伐他汀组血清TNF-α和IL-α水平明显降低(P<0．05)。结论阿托伐他汀通过降低ISO诱导的CHF大鼠细胞因子水平,从而改善左室重构及心脏功能。     

辅酶Q10联合阿托伐他汀对心力衰竭大鼠的氧化作用及心肌重构的影响

目的 研究辅酶Q10联合阿托伐他汀对心衰大鼠氧化作用、心肌重构的影响及其机制.方法 左冠状动脉前降支被结扎并饲养6w的24只大鼠随机分为假手术组、模型组、阿托伐他汀组、辅酶Q10+阿托伐他汀组,每组6只,灌胃给药5 w后测定血清超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量、全心及左室肥厚指数(HW/BW,LVHW/BW)、非梗死区心肌解偶联蛋白2(UCP2)的水平.结果 联合应用辅酶Q10及阿托伐他汀能明显升高SOD活性,降低血清MDA的含量及心肌肥厚指数、下调UCP2的水平(P ＜0.05 ～0.001).结论 辅酶Q10联合阿托伐他汀可能通过抗氧化作用,下调心肌梗死后心衰大鼠心肌细胞内UCP2的水平,降低心肌肥厚指数,改善心肌重构.     

BH3-only protein Bim is involved in myocardial injury induced by co-stress of ischemia and cold stress in rats

Objectives To investigate the effect of co-exposure of myocardial ischemia and cold stress on myocardial injury in rats and the relative mechanism.Methods Myocardial ischemia model was established by ligation of left coronary artery.SD rats were randomly allocated to 4 groups; sham+normal temperature(S group),sham+cold stress(SC group),myocardial ischemia+ normal temperature(Ⅰgroup), myocardial ischemia+cold stress(IC group).On the condition of 26℃,SC and IC groups were keeped in a 4℃artificial chamber for 8h(8;00-16:00) for 4 consecu- tive days.Car diac function was assessed by echocardiography;pathological change was analyzed by HE staining;myocardial infarct size was determined by TTC staining;Bim,Caspase-3 expression in myocardium was determined by western blotting.Results It was demonstrated that co-exposure of myocardial ischemia and cold stress could significantly make the cardiac muscle in abnormal shape,increase the infarct size and the expression of Bim and Caspase-3.Conclusions Co-exposure of myocardial ischemia and cold stress may aggravate the cardiac injury,pro- apoptosis protein Bim is involved.     

冠状动脉内粒细胞集落刺激因子注射治疗猪慢性缺血性心脏病

目的 探讨冠状动脉内粒细胞集落刺激因子(G-CSF)注射治疗慢件缺血性心脏病猪的安全性和可行性.方法健康小型猪20只,成功建立慢性缺血性心脏病动物模型后4周,存活18只,随机分为对照组、G-CSF皮下注射组和G-CSF冠状动脉内注射组,每组6只.冠状动脉内注射组按照60μg/kg经冠状动脉内一次性给予G-CSF,皮下注射组按照5μg·kg-1·d-1连续5 d皮下注射G-CSF,对照组不做任何处理.于动物模型建立前、术后4周及8周分别行冠状动脉造影、99m Tc-甲氧基异丁基异腈(MIBI)/氟-18氟化去氧葡萄糖(18F-FDG)心肌双核素显像(DISA-SPECT)和首过延迟心肌灌注磁共振扣描(MRI),观察左心室射血分数(LVEF)、心肌损伤面积、心肌灌注面积及存活心肌的变化,并行血管、心肌病理学检查,观察新牛血管及心肌凋亡情况.结果冠状动脉内注射G-CSF后,慢性缺血性心脏病猪外周血G-CSF峰值时间为G-CSF动员后5 d,而皮下注射G-CSF峰值出现在动员后7 d,但两组间G-CSF峰值水平未见显著差别[(554.2±54.1)pg/ml比(590.8±87.9)pg/ml,P＞0.05].流式细胞分析显示,皮下注射途径和冠状动脉内注射G-CSF后,外周血 CD34+细胞比例与CD34+/CD133+细胞比例均明显高于对照组,但两组间差异无统计学意义.G-CSF皮下注射组和G-CSF冠状动脉内注射组靶病变血管远段狭窄程度均明显低于对照组(P均＜0.05),但两组间比较差异无统计学意义.MRI结果显示,G-CSF冠状动脉内注射组和G-CSF皮下注射组治疗4周后LVEF较动员前均明显改善(P＜0.01),G-CSF冠状动脉内注射组和G-CSF皮下注射组改善幅度均高于对照组(对照组比G-CSF皮下注射组比G-CSF冠状动脉内注射组:-2.5%±0.8%比5.8%±1.2%比5.0%±1.0%,与对照组比较P均＜0.01),但两种途径间差异无统计学意义.同时,G-CSF冠状动脉内注射组和G-CSF皮下注射组梗死心肌而积均显著减少,左心室重构均显著改善,存活心肌数量均显著增加,血管新生均增加,均抑制心肌细胞凋亡,两种途径问比较差异无统计学意义.结论经冠状动脉内注射G-CSF与皮下注射同样安全有效,可以改善慢性缺血性心脏病小型猪心脏功能.     

Regional vascular adjustments during recovery from myocardial infarction in rats

Left ventricular function and systemic regional blood flow (radioactive microspheres, 15 +/- 5 mu) were studied 1, 3, 10 or 42 days after left coronary occlusion in conscious rats. One day after coronary occlusion, vascular resistance in the skeletal muscle and cutaneous beds increased while stroke work and left ventricular systolic pressure were depressed. Regional blood flow and hemodynamic data were similar for sham and infarction groups at 3 and 10 days after surgery, except for left ventricular end-diastolic pressure, which was significantly increased in rats with infarction (sham versus infarct: 11.5 +/- 1.0 versus 18.4 +/- 3.2 at day 3 and 12.2 +/- 1.4 versus 19.9 +/- 3.2 at day 10) (p less than 0.05). At 42 days after myocardial infarction, manifest heart failure occurred as documented by decreased cardiac output and left ventricular systolic pressure and elevated left ventricular end-diastolic pressure and vascular resistance in the cutaneous, skeletal muscle and renal beds. In a separate group of animals with moderate (33.2 +/- 2% of left ventricle) and large infarctions (45 +/- 1.3% of left ventricle), regional blood flow was compared with the sham group. Rats with a large infarct demonstrated significant (p less than 0.05) reduction in flow to kidney, gut and liver. In rats with a medium sized infarct, only renal blood flow was significantly reduced. It is concluded that in this model of myocardial infarction, early cardiocirculatory depression is followed by a partially compensated state with increased left ventricular end-diastolic pressure and subsequent systemic and regional vasoconstriction which, in turn, may contribute to late deterioration of heart failure.     

Determinants of left ventricular systolic function after acute myocardial infarction: the role of residual myocardial ischaemia

BACKGROUND: Left ventricular systolic function (LVSF) is one of the major determinants of survival after acute myocardial infarction (AMI). Some factors such as the infarct size and localization, and the patency of the infarct-related artery are known determinants of LVSF. However, the long-term effect of myocardial ischaemia on LVSF has been poorly studied in clinical settings. OBJECTIVES: To assess the acute and long-term effects of myocardial ischaemia on LVSF in patients recovering from an AMI. METHODS: A cohort of 74 patients recovering from AMI was studied. Myocardial ischaemia was detected by means of ambulatory electrocardiogram (ECG) monitoring at recruitment (4+/-2 days after AMI), exercise ECG test and stress echocardiography at discharge (7+/-4 days after AMI). LVSF was studied by means of two-dimensional echocardiography at recruitment, at discharge, and at 1, 3, 6 and 12 months after AMI. RESULTS: Patients with myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had worse LVSF at recruitment than those without ischaemia. The presence of myocardial ischaemia on ambulatory ECG monitoring was an independent determinant of LVSF at recruitment together with infarct localization and size (assessed by creatine kinase MB isoenzyme (CK-MB) levels). Patients with signs of myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had a progressive left ventricular dysfunction compared with those without ischaemia. CONCLUSIONS: Residual ischaemia is an independent determinant of LVSF after AMI and its presence implied a progressive worsening of the LVSF. Because left ventricular systolic dysfunction is a major determinant of survival after AMI, its precursors, among them residual myocardial ischaemia, should be identified. Treatment of ischaemia is known to be associated with improved prognosis and improved LVSF.     

计算机辅助心肌造影负荷超声定量评价心肌灌注及局部收缩功能

目的 探讨计算机辅助心肌造影负荷超声(MCSE)定量评价心肌灌注和局部收缩功能的应用价值.方法 采用急性阻断再灌注左室支建立兔模型,根据阻断和再灌注时间分为两组:阻断30 min后再灌注60 min(Ⅰ组)和阻断120 min后再灌注60 min(Ⅱ组).分别在基础状态、阻断、再灌注和多巴酚丁胺负荷(5、10、15和20 μg·kg-1·min-1)行心肌造影超声心动图,造影图像经自制计算机辅助软件处理后,自动标出每个节段的标化造影剂密度(CI),根据标化CI值,彩色编码标记为:0～ -20像素(pix)黄色、-21～ -40 pix蓝色、-41～ -70 pix绿色以及＜-70 pix红色.分别计算出阻断时和再灌注后红色编码区面积,并与荧光微球染色和氯化三苯基四氮唑染色面积对照分析.同时测量各阶段危险心肌的收缩期室壁增厚率(WT).结果 (1)阻断时,危险心肌的WT降到零点或呈负值,CI明显低于基础状态,红色编码区面积与荧光染色危险心肌面积呈正相关(r=0.91,P＜0.01).(2)再灌注和多巴酚丁胺5μg·kg-1·min-1后,各组危险心肌的WT和标化CI仍减低.以标化CI-70 pix为截断值,识别梗死节段的敏感性为95%,特异性为87%.红色编码面积与氯化三苯基四氮唑染色梗死心肌面积呈正相关(r=0.89,P＜0.01).(3)随着多巴酚丁胺剂量的增加,Ⅰ组的标化CI恢复至基础状态,WT逐渐增加超过基础水平,但Ⅱ组仍保持较低水平.结论 计算机辅助心肌造影负荷超声可以定量评价心肌灌注和局部收缩功能,是识别顿抑和梗死心肌安全可行的方法.     

Long-Term Effects of Beta-Adrenergic Blocking Agent Treatment on Hemodynamic Function and Left Ventricular Remodeling in Rats With Experimental Myocardial Infarction: Importance of Timing of Treatment and Infarct Size

Objectives. This study was designed to assess the long-term effects of a beta₁-selective beta-adrenergic blocking agent on mortality, in vivo hemodynamic function, left ventricular volume and wall stress in post-myocardial infarction (MI) rats.Background. Beta-blockers have shown beneficial results in clinical studies after MI. However, the underlying mechanism is not yet understood, and experimental studies have shown conflicting results.Methods. Bisoprolol (60 mg/kg body weight per day) was given 30 min or 14 days after MI or sham operation.Results. The mortality rate was reduced only in early bisoprolol-treated rats (29% vs. 46% in untreated rats, p < 0.05). Heart rate was equally reduced in all treatment groups, and the maximal rate of rise of left ventricular systolic pressure (dP/dt_max) decreased in sham rats and in rats with a small to moderate infarct size. Stroke volume index was unchanged in sham rats and in rats with a small to moderate infarct with early or late bisoprolol treatment and increased in rats with a large infarct in the late bisoprolol group. Left ventricular volume was increased by bisoprolol in sham rats and rats with a small infarct but not in rats with a large infarct.Conclusions. Treatments starting early (30 min) or late (14 days) after coronary artery ligation with bisoprolol increased left ventricular volume in sham rats and in rats with a small infarct but not in rats with a large infarct. Late bisoprolol treatment improved stroke volume index, and early bisoprolol treatment reduced diastolic wall stress, in rats with a large myocardial infarct. Thus, bisoprolol effects on remodeling and cardiac performance after myocardial infarction strongly depend on infarct size and timing of treatment. This finding may explain previous controversial results that did not consider infarct size and timing of treatment.     

贝那普利联合阿托伐他汀钙对急性心肌梗死后心室重构的影响及机制探讨

目的:观察贝那普利及阿托伐他汀钙对急性心肌梗死（AMI）后心室重构的影响。方法: 将符合标准AMI的患者74例随机分为对照组和观察组各37例。观察组在基础治疗基础上加用贝那普利及阿托伐他汀钙,对照组仅加贝那普利基础治疗,坚持服用24周,不能耐受贝那普利的改为替米沙坦。分析3 d和24周超声心动图的观察指标。结果: 观察组的左室收缩末期容积（LVESV）和左室舒张末期容积（LVEDV ）的下降幅度明显高与对照组;左室射血分数(LVEF)和左室快速充盈E波最大流速（VE）和心房充盈A 波最大流速(VA)比值（VE/VA）也明显高于对照组;左室心肌重量指数（LVMI）增高幅度显著小于对照组(均P<005)。结论: 贝那普利及阿托伐他汀钙抑制AMI后心室重构,改善心功能效应明显好于单用贝那普利。     

Heat shock protein induction in rat hearts. A role for improved myocardial salvage after ischemia and reperfusion?

BACKGROUND. To test the hypothesis that the heat shock response is associated with improved myocardial salvage after myocardial ischemia and reperfusion, rats treated with prior whole-body hyperthermia and 24 hours of recovery (n = 26) or 20 minutes of ischemic pretreatment and 8 hours of recovery (n = 24) and control rats (n = 27, n = 24, for hyperthermic and ischemic pretreatment, respectively) were subjected to 35 minutes of left coronary artery (LCA) occlusion and 120 minutes of reperfusion. METHODS AND RESULTS. Although ventricular samples from rats subjected to either hyperthermia (n = 7) or ischemic pretreatment (n = 6) all showed induction of HSP72 (heat shock protein), Western blot analysis revealed significantly greater amounts of HSP72 in samples obtained from rats subjected to hyperthermia compared with those from rats subjected to ischemic pretreatment. Control rats (n = 7) showed no significant presence of myocardial HSP72. After 35 minutes of LCA occlusion and 2 hours of reperfusion, infarct size was significantly reduced in heat-shocked rats compared with controls (8.4 +/- 1.7%, n = 26 versus 15.5 +/- 1.9%, n = 27; p = 0.007; mean +/- SEM; infarct mass/left ventricular mass x 100). There were no significant differences in left ventricular (LV) systolic pressure, heart rate, LV dP/dt, or rate-pressure product between heat-shocked (n = 11) and control (n = 14) rats during the ischemic period. There were no differences in infarct size between ischemically pretreated and control rats subjected to 35 minutes of ischemia and reperfusion (9.7 +/- 2.1%, n = 23 versus 10.0 +/- 2.1, n = 24; p = NS). CONCLUSIONS. In this model of ischemia and reperfusion, prior heat shock was associated with significantly improved myocardial salvage after 35 minutes of LCA occlusion and reperfusion. This improved salvage was correlated with marked HSP72 induction and was independent of the hemodynamic determinants of myocardial oxygen supply and myocardial oxygen demand during the ischemic period. In contrast, mild HSP72 induction by ischemic pretreatment was not associated with improved myocardial salvage after myocardial ischemia and reperfusion. Thus, the absolute levels of HSP72 may be important in conferring protection from ischemic injury in this animal model.     

Cellular basis of ventricular remodeling after myocardial infarction.

To determine whether acute left ventricular failure associated with myocardial infarction leads to architectural changes in the spared nonischemic portion of the ventricular wall, large infarcts were produced in rats, and the animals were sacrificed 2 days after surgery. Left ventricular end-diastolic pressure was increased, whereas left ventricular dP/dt and systolic pressure were decreased, indicating the presence of severe ventricular dysfunction. Absolute infarct size, determined by measuring the fraction of myocyte nuclei lost from the left ventricular free wall, averaged 63%. Transverse midchamber diameter increased by 20%, and wall thickness diminished by 33%. The number of mural myocytes in this spared region of the left ventricular free wall decreased by 36% and the capillary profiles by 40%. Thus, side-to-side slippage of myocytes in the myocardium occurs acutely in association with ventricular dilation after a large myocardial infarction. In order to analyze the chronic consequences of myocardial infarction on ventricular remodeling, a second group of experiments was performed in which the left coronary artery was ligated and the functional and structural properties of the heart were examined 1 month later. In infarcts affecting an average 38% of the free wall of the left ventricle (small infarcts), reactive hypertrophy in the spared myocardium resulted in a complete reconstitution of functioning tissue. However, left ventricular end-diastolic pressure was increased, left ventricular dP/dt was decreased, and diastolic wall stress was increased 2.4-fold. After infarctions resulting in a 60% loss of mass (large infarcts), a 10% deficit was present in the recovery of viable myocardium. Functionally, ventricular performance was markedly depressed, and diastolic wall stress was increased 9-fold. The alterations in loading of the spared myocardium were due to an increase in chamber volume and a decrease in the myocardial mass/chamber volume ratio that affected both infarct groups. Thus, decompensated eccentric ventricular hypertrophy develops chronically after infarction and growth processes in myocytes are inadequate for normalization of wall stress when myocyte loss involves nearly 40% or more of the cells of the left ventricular free wall. The persistence of elevated myocardial and cellular loads may sustain the progression of the disease state toward end-stage congestive heart failure.