肺缺血再灌注损伤模型犬接受去氢骆驼蓬碱干预后无明显肺保护作用

背景：炎性细胞活化、氧自由基的产生是肺缺血再灌注损伤发生的重要因素。在常用的肺保护液中增加可能具有抑制炎症、抗氧化作用的药物,使保护液进行一定的改良,对肺缺血再灌注损伤的研究及保护移植肺的功能具有重要的意义。目的：探讨去氢骆驼蓬碱对犬肺缺血再灌注损伤的作用。方法：将12只健康杂交犬随机分为两组,每组6只。建立犬肺缺血再灌注损伤模型,采用顺灌方式行保护液肺灌注,实验组给予低钾右旋糖苷保护液＋去氢骆驼蓬碱溶液灌注,对照组给予低钾右旋糖苷保护液。缺血2h后,恢复左肺循环,两组于再灌注后采集左肺组织及血液标本,检测细胞因子水平,计算肺湿/干质量比;收集支气管肺泡灌洗液,观察各项病理指标;连续测量记录主肺动脉压、左肺动脉压和右肺动脉压。结果与结论：两组于再灌注2,4h时左肺组织及血液中的白细胞介素17、肿瘤坏死因子α及内皮素1水平差异均无显著性意义（P〉0.05）,两组再灌注4h后的支气管肺泡灌洗液中性粒细胞数目、淋巴细胞数目、肺泡损伤指数及血管壁水肿程度差异均无显著性意义（P〉0.05）,两组肺湿/干质量比差异均无显著性意义（P〉0.05）,经方差分析,两组主肺动脉压、左肺动脉压及右肺动脉压差异均无显著性意义（P〉0.05）。结果可见通过对细胞因子、病理指标、肺组织湿/干质量比及肺动脉压力分析,去氢骆驼蓬碱在犬肺原位常温缺血再灌注损伤模型中没有明显的肺保护作用。     

肺缺血后适应对兔急性心肌缺血再灌注损伤的作用

目的通过在体兔心肌缺血再灌注模型，探讨肺缺血后适应是否具有减轻心肌缺血再灌注（I／R）损伤的作用及其可能的作用机制。方法将30只兔随机分成3组，每组10只。对照组：结扎冠状动脉左前降支（LAD）30min，再灌注3h。缺血后适应组：结扎LAD20min时阻断左肺动脉5min，然后松开5min，继而心肌再灌注至3h。药物＋缺血后适应组：于结扎LAD25min后经耳缘静脉注射一氧化氮合酶（eNOS）抑制剂L-NAME10mg／kg，余同缺血后适应组。分别于缺血前、再灌注开始前、再灌注3h末取兔血，测定各组血清肌酸激酶（CK）、丙二醛（MDA）、及超氧化物歧化酶（SOD）的水平。结果再灌注3h末，CK活性后适应组低于对照组和药物＋缺血后适应组，MDA活性后适应组低于对照组和药物＋后适应组，SOD活性后适应组高于对照组和药物＋后适应组。药物＋后适应组与对照组比较，CK活性、MDA活性和SOD活性均无统计学意义。结论肺缺血后适应对急性心肌缺血再灌注损伤具有保护作用；减少氧自由基的产生和释放NO是肺缺血后适应的作用机制。     

蝙蝠葛酚性碱对家兔心脑缺血-再灌注损伤保护作用的研究

目的　探讨蝙蝠葛酚性碱 (PAMd)抗心、脑同时缺血再灌注损伤的机制。方法　采用结扎家兔左冠状动脉前降支及双侧颈总动脉 30 m in后再灌注造成心、脑缺血再灌注模型 ,观察 PAMd对缺血前后及再灌注后不同时间血清、左心室、海马、皮质及小脑中丙二醛 (MDA)含量和超氧化物歧化酶 (SOD)活性的影响。结果　家兔心、脑缺血再灌注 10 min后血清 MDA含量显著升高 ,SOD活性显著降低 (P均 <0 .0 5 )。PAMd3.5 mg/ kg显著降低心、脑缺血再灌注后血清及组织 MDA含量 ,升高 SOD活性 (P均 <0 .0 5 )。结论PAMd通过减轻脂质过氧化所造成的损伤 ,提高 SOD活性 ,对心、脑缺血再灌注损伤具有一定保护作用。     

左旋精氨酸对兔肺缺血/再灌注损伤时细胞凋亡的影响

目的观察左旋精氨酸对免肺缺血／再灌注损伤中细胞凋亡的影响。方法复制单侧免肺缺血／再灌注损伤模型．随机分为三组：对照组（C组）、缺血／再灌注组（I／R组）和左旋精氨酸组（L—Arg组），每组10只。再灌注180min时取肺组织，观察超氧化物歧化酶（SOD）活性、丙二醛（MDA）浓度、一氧化氮（NO）含量、肺湿干比（W／D）、肺泡损伤数定量评价指标（IQA）及肺组织细胞凋亡指数（At）。结果I／R组与C组比较，SOD活性、NO含量明显降低（P〈0．01），MDA、W／D、IQA、AI明显升高（P〈0．01），L—Arg组与I／R组相比较，SOD活性、NO含量均明显升高（P〈0．01），MDA、W／D、IQA、AI不同程度降低（P〈0．05）。结论左旋精氨酸可通过提高体内NO水平、降低氧自由基水平、减轻脂质过氧化反应，抑制肺组织细胞凋亡，从而减轻肺损伤。     

Oxidative stress in patients with COPD and pulmonary hypertension

OBJECTIVE: Oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Oxidant/antioxidant imbalance has also been reported in various forms of pulmonary hypertension. The present study aimed to assess systemic oxidative stress, as reflected by serum malondialdehyde (MDA) concentrations and activities of antioxidant enzymes in erythrocytes [glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT)] in patients with and without pulmonary hypertension secondary to COPD. PATIENTS AND METHODS: Seventy-five patients (58 male) with COPD (mean age 65.1 +/- 1.2 years; mean smoking history 35.6 +/- 3.8 pack-years) were studied. Twenty-one healthy non-smokers served as a control group. Pulmonary function was evaluated with body plethysmography; mean and systolic pulmonary artery pressures (Ppa) were assessed with Doppler echocardiography. Serum concentrations of MDA and activities of GPX, SOD and CAT in washed red blood cells were measured using spectrophotometry. RESULTS: Pulmonary hypertension was present in 28 patients with COPD (systolic Ppa: 46.4 +/- 2.3 mmHg; mean Ppa: 26.0 +/- 1.9 mmHg) and absent in 47 (systolic Ppa: 22.9 +/- 0.8 mmHg; mean Ppa: 13.4 +/- 0.6 mmHg). Compared with the healthy control group, all the patients (with or without pulmonary hypertension) had higher serum MDA concentrations (1.5 +/- 0.1 versus 2.3 +/- 0.1 versus 2.3 +/- 0.1 nmol/mL, ANOVA, P < 0.001) and lower erythrocyte GPX activity (51.3 +/- 3.2 versus 42.2 +/- 2.0 versus 41.3 +/- 2.5 U/g Hb, P = 0.029), whereas SOD (1121.1 +/- 29.0 versus 1032.6 +/- 21.8 versus 1032.7 +/- 36.2 U/g Hb, P = 0.063) and CAT activities (4.9 +/- 0.2 versus 4.6 +/- 0.1 versus 4.7 +/- 0.2 U/g Hb; P= 0.454) were similar. No differences were observed in serum MDA concentrations or activities of GPX, SOD and CAT in erythrocytes between COPD patients with and without pulmonary hypertension. CONCLUSION: The study demonstrates the presence of oxidative/antioxidative imbalance in the systemic circulation in patients with COPD: compared with healthy subjects, COPD patients had higher serum MDA concentrations and lower GPX activity in erythrocytes. The magnitudes of the increase in MDA and reduction in GPX activity were similar in COPD patients with pulmonary hypertension and in those with normal pulmonary artery pressures.     

腺苷对兔缺血再灌注心肌和ET-1作用的研究

目的评价腺苷对缺血再灌注心肌的作用和对ET-1的影响,探讨腺苷预处理对缺血再灌注心肌保护作用的可能机制。方法家兔24只,随机分成对照组、腺苷预处理组、腺苷治疗组,每组8只。冠状动脉结扎40min,再灌注3h制备缺血再灌注模型。测定缺血前和再灌注3h后血CK的变化和心肌梗死区重量的大小,比较各组再灌注3h后SOD和MDA的变化。采用放免法测定结扎冠脉前,再灌注时,再灌注后30、60、120min血浆ET-1的变化。结果与对照组和腺苷治疗组相比,腺苷预处理组在再灌注3h后血清中CK、SOD、MDA的水平降低(P<0.01),心肌梗死面积明显减少(P<0.01);与对照组和腺苷治疗组相比,腺苷预处理组除结扎冠脉前,其余时间点ET-1的水平明显降低(P<0.01)。结论腺苷预处理可减轻再灌注损伤,对缺血再灌注心肌具有明显的保护作用,腺苷可能通过保护内皮细胞减少血浆ET-1的水平,减轻缺血再灌注损伤。     

兔低位腹主动脉阻断后丙二醛(MDA)和超氧化物歧化酶(SOD)的观察

目的观察兔低位腹主动脉阻断后不同时间血液中丙二醛（MDA）和超氧化物歧化酶（SOD）的变化。方法建立兔腹主动脉阻断1、1．5h的模型，检测阻断前、再灌注不同时点血液中丙二醛（MDA）和超氧化物歧化酶（SOD）的变化。结果与对照组比较，阻断1h组（B1）再灌注时点血液中MDA升高、SOD降低不明显（P〉0．05），阻断1．5h组（B2）再灌注时点血液中MDA升高，SOD降低（P〈0．05）。结论兔低位腹主动脉阻断1h缺血再灌注损伤不明显，阻断1．5h有明显的缺血再灌注损伤。兔低位腹主动脉阻断应控制在1h以内。     

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.     

参附注射液对大鼠肺缺血再灌注损伤

目的：研究参附注射液（shenfu injection．SF）对大鼠肺缺血再灌注损伤（lung ischemia reperfusion injury，LIRI）中肺组织细胞凋亡的保护作用，并探讨其可能机制。方法：雄性SD大鼠42只，随机分为假手术组（Sh组）、肺缺血再灌注组（IR组）和参附注射液组（SF组），建立在体单侧肺缺血再灌注模型，缺血45min后再灌注3、6h。SF组于阻断肺门前30min腹腔注射SF 10mL／kg。于实验结束点取肺组织，分别以Annexin-V-PI双染法通过流式细胞仪检测细胞凋亡率，免疫组化二步法检测caspase-3表达，同时测定丙二醛（MDA）浓度和超氧化物歧化酶（SOD）活性，以及光镜和电镜检查。结果：与Sh组比，IR组肺组织细胞凋亡率、caspase．3表达、MDA浓度升高，SOD活性下降，差异均有显著性（P〈0．01）；SF组较IR组细胞凋亡率、caspase-3表达、MDA浓度下降，SOD活性升高，差异亦均有显著性（P〈0．01）。形态学观察发现sF组肺组织损伤明显轻于IR组。结论：SF可能通过下调caspase-3表达而阻止细胞凋亡，从而减轻uRI中肺组织损伤。[著者文摘]     

依达拉奉对家兔失血性休克缺血-再灌注损伤的保护作用

目的 观察兔失血性休克再灌注过程中血浆丙二醛(MDA)、一氧化氮(NO)与超氧化物岐化酶(SOD)水平的动态变化,以及肺脏、肾脏病理改变;并探讨依达拉奉的保护作用.方法 29只家兔全身肝素化后随机分为三组:假手术组(C组,n=7)、失血性休克再灌注组(I/R组,n = 10)和依达拉奉保护组(L/R-edaravone组,n=12).后两组制作失血性休克再灌注模型,在10 min内通过左股动脉放血,维持平均动脉压(MAP)40 mmHg达到60 min.I/R-edar-avone组静脉应用依达拉奉.然后开始复苏,要求在60 min内回输全部失血和等量生理盐水,使MAP维持在失血前70%以上.休克后10 h L/R-edaravone组静脉再次应用依达拉奉.在复苏后20 h处死所有家兔,同时取所有兔的右肺部分组织和右肾部分组织作病理检查.分别测休克前、休克1 h、再灌注后1 h、5 h及20 h血浆MDA、SOD、NO含量.结果 休克前三组动物血浆MDA、NO及SOD含量均无显著统计学差异.休克后I/R组家兔血浆MOA(5.35±0.29)μmol/L及NO(27.75±2.88) μmol/L水平均较C组的[(4.44±0.59)μmol/L,(25.01±4.95) μmol/L]要高,而I/R组的SOD水平(194.58±14.42)U/ml 较C组(210.86±24.54)U/ml要低(P均<0.01).复苏后20 h这些变化更加明显,I/R组MDA和NO水平持续增加[(5.69±0.24)μmol/L,(28.01±3.10)μmol/L,P<0.05],而SOD水平继续下降[(151.83±9.36)U/ml,P<0.05].与I/R组比较,I/R-edaravone组的MDA水平显著降低[(3.48±0.23) μmol/L,P<0.01],SOD水平明显升高[(195.10±11.87)U/ml,P<0.01].病理检查提示依达拉奉可以减轻肺脏和肾脏病理损害.结论 依达拉奉通过清除自由基,有效减轻失血性休克再灌注过程中重要脏器的损害.     

多层螺旋CT灌注成像对肺栓塞-再灌注损伤的实验研究

目的应用CT灌注成像技术量化评价肺栓塞再灌注损伤,探讨肺栓塞再灌注损伤形成机制。方法选择14只健康杂种犬为实验对象。利用SwanGanz导管模拟肺膈叶动脉栓塞再灌注。栓塞前、栓塞24h和再通4h要分别进行肺动脉压测定、CT灌注成像和血清超氧化物歧化酶(SOD)的测定。结果再灌注肺损伤主要表现为急性渗透性肺水肿。再灌注损伤肺的BF[(325.69±134.00)ml·min-1·100g-1)]和MTT[(1.98±0.44)s]与栓塞前正常基线值[(409.58±88.42)ml·min-1·100g-1)和(1.87±0.48)s]的差异具有统计学意义(P<0.01和P<0.05)。再灌注4h的肺动脉压[(25.79±6.25)mmHg]和超氧化物歧化酶的平均值[(388.79±25.07)U/ml]与栓塞前正常基线值[(22.31±3.77)mmHg和(404.38±23.81)U/ml]相比均具有统计学差异(P<0.05和P<0.05)。再灌注损伤侧肺的湿/干重比率(6.29±1.23)显著大于对侧肺(4.54±1.19),其差异也具有统计学意义(P<0.01),说明再灌注水肿增加了肺组织的含水量。结论CT灌注成像有效反映肺栓塞再灌注损伤的血流动力学改变。氧自由基对肺栓塞再灌注损伤的形成起重要作用。     

Targeted delivery and improved therapeutic potential of catalase by chemical modification: combination with superoxide dismutase derivatives

Four types of bovine liver catalase (CAT) derivatives, succinylated (Suc-CAT), galactosylated (Gal-CAT), mannosylated (Man-CAT), and polyethylene glycol conjugate (PEG-CAT), were synthesized and their pharmacokinetics and therapeutic potential in a hepatic ischemia/reperfusion injury model were studied in mice. About 90% of the CAT enzymatic activity was retained after chemical modification. Biodistribution studies showed that 111indium (111In)-Gal-CAT accumulated selectively in the liver parenchymal cells as 111In-CAT, whereas an increased amount of 111In-Suc-CAT and 111In-Man-CAT was delivered to liver nonparenchymal cells. 111In-PEG-CAT exhibited prolonged retention in plasma. Pharmacokinetic analysis revealed that the hepatic uptake clearances of 111In-Suc-CAT, 111In-Gal-CAT, and 111In-Man-CAT were much greater than that of 111In-CAT, whereas that of 111In-PEG-CAT was very small. In the ischemia/reperfusion injury model, in which hepatic injury was induced by occlusion of the portal vein for 30 min followed by 1 h reperfusion, the elevation of plasma glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels was slightly inhibited by treatment with native CAT or Gal-CAT. PEG-CAT was less potent. In contrast, Suc-CAT and Man-CAT effectively suppressed the increase in plasma glutamic pyruvic transaminase and glutamic oxaloacetic transaminase. Coinjection of mannosylated superoxide dismutase marginally improved the inhibitory effects of CAT derivatives. These results demonstrate that targeted CAT delivery to liver nonparenchymal cells via chemical modification is a promising approach to prevent hepatic injuries caused by reactive oxygen species. The potential usefulness of combining of CAT and superoxide dismutase derivatives is also demonstrated.     

葛根素对家兔心肌缺血-再灌注损伤的保护作用

目的:探讨葛根素抗心肌缺血-再灌注损伤的机制.方法:采用结扎冠状动脉左室支方法制备兔心肌缺血-再灌注损伤模型,用四道生理记录仪测定动物的血流动力学及左室功能变化.将40只家兔随机分组.10只作为空白对照组;10只作为假手术对照组;余20只制模,其中10只为模型组,另10只则在结扎左室支前20 min o40 min20 min(LPO)含量及超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSHPx)活性;实验完毕后取缺血-再灌注损伤区心肌组织0.5 g,分别测定组织匀浆中LPO含量、SOD活性及GSH-Px/LPO.结果:与模型组比较,葛根素保护组动物左室内压峰值(LVSP)、左室内压上升最大速率(LV dp/dt max)和左室内压下降最大速率(LV-dp/at max)均显著升高(P<0.05或P<0.01);血清中LPO含量明显降低(P<0.05),而GSH-Px/LPO升高非常明显(P<0.01);缺血一再灌注损伤区心肌组织中LPO含量显著降低,SOD活性和GSH-Px/LPO<0.05).结论:葛根素可通过提高对自由基的清除及拮抗脂质过氧化反应而起到保护缺血-再灌注损伤心肌的作用.     

维生素C和维生素E对移植肺再灌注损伤保护作用的实验研究

目的：观察维生素C（Vit）和维生素E（VitE）对大鼠移植肺再灌注损伤的保护作用。方法：采用大鼠自体左肺模拟原位移植模型，治疗组分别于再灌注前10min静脉注入VitC（200mg/kg）和（或）VitE乳剂（100mg/kg）。再灌注4h后观测移植肺气体交换功能，顺应性，血管通透性，脂质过氧化程度，ATP含量以及组织病理学变化。结果：缺血再灌注（I／R）组移植肺气体交换功能，顺应性降低，脂质过氧化程度增加，ATP含量下降，组织病理学改变明显（P＜0．01）；给药组移植肺气体交换功能，顺应性与I／R组相比无明显改善（P＞0．05），其它指标均有不同程度的改善，以VitC和VitE合用时改善最为显著（P＜0．01）。结论：VitC和VitE对移植肺再灌注损伤具有协同保护作用。     

内毒素预处理对兔肝脏缺血-再灌注后肺损伤的保护效应

目的 探讨内毒素预处理对肝脏缺血-再灌注后肺损伤的影响及机制.方法 将48只新西兰大白兔随机分为一般对照组(C一般组)和预处理对照组(C预处理组),缺血-再灌注组(IR组)和预处理再灌注组(LPS+IR组),每组12只.C一般组仅行手术解剖;C预处理组手术解剖前3 d分别经腹腔注射0.5、0.5和1.0 mg/kg脂多糖(LPS)进行内毒素预处理;IR组夹闭肝门30 rmn,再灌注4 h,进行肝脏缺血.再灌注;LPS+IR组行内毒素预处理后再行肝脏缺血.再灌注.检测各组再灌注后4 h血清内毒素、肿瘤坏死因子-α(TNF-α)、肺湿干比、灌洗液蛋白含量、组织匀浆丙二醛(MDA)、超氧化物歧化酶(SOD)、肺损伤率及肺泡巨噬细胞核因子-KB(NF-kB)活性的变化.组间比较采用单因数方差分析.结果 C一般组和C预处理组各项检测指标差异无统计学意义(P>0.05).LPS+IR组血清TNF-α[(48.31±5.31)pg/ml vs.(56.47±5.09)pg/ml,P<0.01]、肺湿干比[(4.98±0.33)vs.(5.22±0.31),P=0.03]、灌洗液蛋白含量[(0.68±0.11)g/L vs.(0.76±0.10)g/L,P:0.04]、MDA[(0.86±0.06)mnol/mg vs.(0.93±0.07)nmoL/mg,P=0.02]、肺损伤率[(13.4±4.3)%vs.(17.4±4.1)%,P=0.03]及肺泡巨噬细胞NF-kB活性[(5.82±1.12)OD/m2 vs.(7.40±1.26)OD/mm2,P<0.01]明显低于IR组;同时LPS+IR组SOD[(90.30±7.38)U/mg vs.(84.44±7.90)U/mg,P=0.04]明显高于IR组.结论 内毒素预处理可以减轻肝脏缺血.再灌注后肺损伤,其机制与降低了血清TNF-α产生及抑制肺泡巨噬细胞中NF-kB活化有关.     

The effects of radical scavengers and leukocyte-depleted blood on reperfusion injury of extirpated rabbit lung.

Oxygen radicals produced by polymorphonuclear leukocytes were considered primarily responsible for reperfusion injury in lung transplantation. Using the extirpated rabbit lungs as a transplant model, we measured lung water volume, the oxygen radicals of lung tissue using a direct method (electron spin resonance) and an indirect method (measurement of peroxide lipids). The effects of free radical scavengers, human superoxide dismutase (h-SOD) and catalase (CAT), and leukocyte-depleted blood on reperfusion injury were evaluated in three experimental groups. Group I (n = 8, control): Lung reperfusion was performed with blood from other rabbits. Group II (n = 7): Immediately before reperfusion, h-SOD (1,500 u/ml) and CAT (3,000 u/ml) were added to the blood. Group III (n = 7): Reperfusion was performed with the leukocyte-depleted blood. Severe pulmonary edema and an elevation of malondialdehyde (MDA) occurred in Group I. In Group II, addition of radical scavengers to the reperfusion blood produced only mild pulmonary edema, but an elevation of MDA occurred as in Group I. In Group III, pulmonary edema and MDA elevation were almost completely suppressed.     

Effect of diltiazem on regional oxygenation of reperfused myocardium

Reperfusion after 2 hr of experimental ischemia results in reduced blood flow to the reperfused region, as well as elevated regional O2 extraction in that region. The aim of the present study was to determine whether diltiazem, administered during reperfusion, can improve regional blood flow and lower O2 extraction in the previously occluded region. In open-chest anesthetized dogs, 2-hr occlusion of the left anterior descending coronary artery was followed by a 4-hr period of reperfusion. In 7 of the 15 animals, diltiazem (0.45 micrograms/kg/min) was infused i.v. during the reperfusion period; this was preceded by a loading dose of 0.18 micrograms/kg 10 min before release. Small artery and vein O2 saturations obtained microspectrophotometrically were combined with regional blood flow measurements using radioactive microspheres to determine regional myocardial O2 consumption. In both groups, coronary occlusion lowered regional flow to a similar level. After a 4-hr reperfusion, flow to the subendocardial region of treated hearts was significantly greater than that to the untreated reperfused myocardium (75.6 +/- 46.4 vs. 40.3 +/- 25.8 ml/min/100 g), and did not differ from the preocclusion level. The subendocardium/subepicardium flow ratio was reversed in occluded and untreated reperfused myocardium (subendocardium flow less than subepicardium flow), but was not reversed in treated reperfused regions. Myocardial oxygen extraction was 11.0 +/- 2.4 ml of O2/100 ml of blood in the untreated reperfused subendocardium, and was significantly decreased to 8.5 +/- 0.9 ml of O2/100 ml in the treated subendocardium. The proportion of individual veins having O2 saturations below 25% was significantly reduced by diltiazem treatment from 45.2 to 22.7%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ex vivo reversal of heparin-mediated cardioprotection by heparinase after ischemia and reperfusion.

Glycosaminoglycans, including heparin, have been demonstrated both in vitro and in vivo to protect the ischemic myocardium against reperfusion injury. In the present study, we sought to determine whether the cardioprotective effects of heparin administration could be reversed by the heparin-degrading enzyme heparinase. New Zealand white rabbits were pretreated with heparin (300 U/kg i.v.) or vehicle (saline). Two hours after treatment, hearts were removed, perfused on a Langendorff apparatus, and subjected to 25 min of global ischemia, followed by 45 min of reperfusion. Hemodynamic variables were obtained before ischemia (baseline) and every 10 min throughout the reperfusion period. Compared with vehicle-treated rabbits, the left ventricular end-diastolic and left ventricular developed pressures were improved significantly (p <.05) in the heparin-treated group. Ex vivo administration of heparinase (5 U/ml) immediately before the onset of global ischemia was associated with a reversal of the heparin-mediated cardioprotection. The uptake of a radiolabeled antibody to the intracellular protein myosin and creatine kinase release were used to determine membrane integrity and discriminate between viable and nonviable myocardial tissue. The uptake of radiolabeled antimyosin antibody and release of creatine kinase after reperfusion were increased in heparin-pretreated hearts exposed to heparinase, indicating a loss of membrane integrity and increased myocyte injury. These results demonstrate that neutralization of heparin by heparinase promotes increased myocardial injury after reperfusion of the ischemic myocardium.     

Pretreatment with probucol attenuates cardiomyocyte apoptosis in a rabbit model of ischemia/reperfusion

Objective. Apoptosis plays an important role in ischemic reperfusion injury. Probucol is a hypolipidemic agent and has antioxidant activity, which may inhibit the oxidative modification of low‐density lipoprotein cholesterol. Studies have demonstrated that probucol improves left ventricular function, prevents left ventricular dilatation, and reduces cardiac fibrosis. However, the exact mechanism of probucol on the cardioprotective effect is not known. The objective of the present study was to examine the effect of probucol on ischemia/reperfusion‐induced cardiomyocyte apoptosis. Material and methods. Thirty male New Zealand White rabbits were randomly divided into sham, control, and treated groups, each group comprising 10 rabbits. Before establishment of the ischemia/reperfusion model, animals in the treated group were additionally fed daily with probucol (1000?mg per day) for 4 weeks. In the sham group, the heart was exposed after the chest had been opened, but the coronary artery was not ligated. The animals were killed 150?min after the procedure. In the other two groups, the rabbits were subjected to 30‐min of coronary occlusion followed by a 2‐h reperfusion. A blood sample was drawn from the right atrium before the animal was killed. The apoptotic myocytes were detected by terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labelling. Expression of caspase‐3 and mitochondrial cytochrome c release was detected by immunohistochemical analysis and Western blot analysis. The level of serum superoxide dismutase (SOD) was tested using the xanthine oxidase method, and the content of serum malondialdehyde (MDA) was measured by colorimetry. Results. As compared with the sham group, the control group had a significantly higher apoptotic index ((32.48±4.56)?% versus (0.56±0.18)?%, p<0.01) and serum MDA concentration (2.70±0.64 versus 1.06±0.46?µmol/L, p<0.01), and a significantly lower serum SOD level (144.27±21.69 versus 204.64±16.67?µU/L, p<0.01). Probucol pretreatment apparently caused a decrease in the apoptotic index ((21.64±3.08)?%, p<0.01 versus the sham or control group) and serum MDA concentration (1.95±0.51?µmol/L, p<0.01 versus the sham or control group), and increased the levels of serum SOD (162.61±16.13?µU/L, p<0.01 versus the sham group; p<0.05 versus the control group). The caspase‐3 activation and mitochondrial cytochrome c release in the control group were also higher than those in the treated group (p<0.01). Conclusions. The present study shows that probucol attenuates ischemia/reperfusion‐induced cardiomyocyte apoptosis. The protective effect of probucol on the myocardium may be partly due to its antioxidant activity.     

Normothermic liver ischemia in rats: xanthine oxidase is not the main source of oxygen free radicals

We studied the effect of allopurinol (ALL) on the activity of xanthine dehydrogenase (XDH), xanthine oxidase (XOX), superoxide dismutase (SOD), and catalase (CAT) in rat liver during ischemia followed by 60 min of reperfusion. We induced 60-min ischemia in the median and left lobes by clamping the hepatic artery and portal branches. The percentage XOX relative to total oxidase activity increased significantly in the control group, from 10% during the stabilization period to 18% after 60 min of reperfusion. The XDH activity decreased during reperfusion. Activity of both XDH and XOX was almost completely blocked by ALL. The activity of SOD and CAT did not differ significantly between the ALL group and controls after 60 min of reperfusion. ALL treatment did not affect liver injury parameters, as concentrations of lactate dehydrogenase (LDH) and alanine transferase (ALT) increased in plasma after ischemia, both in controls and in the ALL-treated group. We concluded that ischemia promotes conversion of XDH to XOX during reperfusion. XOX may not be the main source of free radical production, since intracellular scavengers (SOD and CAT) did not differ significantly between controls and the ALL-treated group, despite the fact that ALL blocked XOX activity completely.