二氮嗪对缺血再灌注心肌细胞脂质过氧化反应和超微结构的影响

目的:研究二氮嗪对体内大鼠心脏缺血再灌注损伤的保护效果并对其作用机制进行初步探讨。方法:健康SD大鼠随机分为两组,对照组静脉注射相应量溶媒,实验组按12.5 mg/kg剂量静脉注射二氮嗪进行预处理。10 min后行左侧开胸结扎前降支,造成局部心肌缺血2 h,恢复灌注2 h后取心脏,测量缺血心肌组织丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性,同时电镜观察缺血区心肌细胞超微结构的改变。结果:与对照组相比,实验组MDA含量明显降低(P<0.05),超微结构显著改善,但 SOD活性却无明显改变。结论:二氮嗪对体内大鼠心脏缺血再灌注损伤具有较好的保护作用,其机制可能是通过减轻脂质过氧化反应而发挥作用。     

肝脏缺血再灌注损伤与脂质过氧化反应的关系

肝脏缺血再灌注损伤(hepatic ischemiareperfusion injury,HIRI)是由多种因素如:线粒体损伤、内质网应激、活性氧自由基(reactive oxygen species,ROS)大量生成、钙超载、各种细胞因子释放等引起胞内或胞外信号转导途径改变共同造成的细胞凋亡或细胞坏死的病理现象.脂质过氧化反应(lipid peroxidation,LP)可以笼统的描述为脂质尤其是质膜系统的主要组成成分-多不饱和脂肪酸(polyunsaturated fatty acids PUFAs)中的碳碳双键被氧化物如ROS攻击的生物学反应.在HIRI中,LP贯穿整个生物学反应过程,尤其是线粒体的脂质过氧化(mitochondrial lipid peroxidation,MLP),可能是HIRI的中心分子事件,值得进一步的探索与研究.     

电针足三里穴对兔肺缺血再灌注损伤脂质过氧化反应的影响

目的研究电针足三里穴对在体家兔肺缺血再灌注损伤的影响。方法28只新西兰家兔采用在体肺热缺血再灌注损伤模型．随机分四组（n=7）。A组：假手术组。左开胸游离支气管和肺动脉、静脉后维持通气180min。B组：缺血再灌注组，左开胸游离支气管和肺动脉、静脉后阻断左肺门60min．开放再通气120min。C组：阻断左肺门60min后．开放再通气即刻电针足三里穴旁5mm处30 min．继续双肺通气90min。D组：电针足三里穴＋缺血再灌注组，阻断左肺门60min后。开放再通气即刻电针足三里穴30min．继续双肺通气90min。观察并记录各组动物术中平均动脉压和心率的改变及实验结束时肺组织丙二醛（MDA）和髓过氧化物酶（MPO）含量以及肺组织湿/干重比（W/D）和血气变化。结果各组动物相应时间点的心率比较，均无统计学意义（P〉0.05）。自再灌注30min开始，与B组比较。C组平均动脉压显著降低（P〈0．05），D组平均动脉压与B组比较无统计学意义（P〉0．05）。B组肺组织MDA和MPO含量、W／D及PaCO2值均较A组升高．pH和PaO2值显著降低（P〈0．05或P〈0．01）；D组肺组织MDA和MPO含量、W／D及PaCO2值均较B组降低，pH和PaO2值显著升高（P〈0．05或P〈0．01）。结论电针家兔足三里穴可明显抑制肺缺血再灌注损伤时肺组织MDA和MPO的产生，减轻肺水肿的发生，改善血气变化及酸碱失衡．对在体家兔肺缺血再灌注损伤有一定的保护作用。     

衰老大鼠心肌对缺血再灌注损伤的敏感性研究

目的观察衰老大鼠心肌对缺血再灌注损伤的敏感性,并探讨其可能的机制。方法成年和老年雄性Wistar大鼠各12只,分为4组：成年假手术组、成年缺血再灌注组、老年假手术组和老年缺血再灌注组,每组6只,进行缺血30 min再灌注3 h。脱氧核糖核苷酸末端转移酶介导的缺口末端标记(TUNEL)法检测心肌细胞凋亡,比色法检测心肌组织半胱胺酸蛋白酶蛋白-3 (caspase-3)活性,化学发光法测定心肌组织总一氧化氮(NOx)含量,ELISA法检测心肌过氧亚硝基(ONOO~-)含量。结果老年组缺血再灌注引起心肌细胞凋亡的程度明显高于成年组,凋亡指数分别为(14．6±1.7)%、(19．0±2．1)%,差异有统计学意义(P＜0．05)；caspase-3活性：成年组为(340±32)μmol/mg,老年组为(436±35)μmol/mg,差异有统计学意义(P＜0．05)；心肌组织中NOx含量：成年缺血再灌注组、老年缺血再灌注组分别为成年假手术组的(2．1±0．2)、(4．4±0．5)倍,差异有统计学意义(P＜0．05)；ONOO~-含量：成年缺血再灌注组和老年缺血再灌注组分别为(4．68±0．15)nmol/g、(7．25±0．18)nmol/g,差异有统计学意义(P＜0．05)。结论老年大鼠对心肌缺血再灌注损伤的敏感性增加,可能的原因是老年鼠心脏中NO的毒性衍生物ONOO~-含量增加,从而导致功能蛋白的硝基化。     

盐酸氢吗啡酮降低缺血再灌注大鼠心肌损伤

目的探讨盐酸氢吗啡酮对缺血再灌注(I/R)大鼠心肌损伤的影响。方法健康SPF级雄性成年SD大鼠108只随机分为假手术(S)组、I/R组和盐酸氢吗啡酮预先给药(H)组,每组36只,建立大鼠I/R模型,于再灌注120 min,酶联免疫吸附实验(ELISA)检测血清白细胞介素(IL)-6、IL-10、超氧化物歧化酶(SOD)和丙二醛(MDA)浓度。2,3,5-氧化三苯基四氮唑(TTC)染色法确定心肌梗死面积。Western印迹检测心肌组织Toll样受体(TLR)-4、Bcl-2、Bax和酶切caspase3的蛋白表达。结果与S组比较,I/R组IL-6、IL-10和MDA的浓度均明显升高,SOD浓度明显降低,心肌梗死面积明显升高,TLR-4、Bax和酶切caspase3的蛋白表达均明显升高,Bcl-2蛋白表达明显降低(P0.05);与I/R组比较,H组IL-6和MDA浓度均明显降低,IL-10和SOD浓度明显升高,心肌梗死面积明显降低,TLR-4、Bax和酶切caspase3的蛋白表达均明显降低,Bcl-2蛋白表达明显升高(P0.05)。结论盐酸氢吗啡酮可通过对炎性因子IL-6、IL-10、MDA和SOD,心肌梗死面积,TLR-4信号及凋亡相关的Bcl-2、Bax和酶切caspase3表达的调节对I/R大鼠心肌损伤起保护作用。     

缺血心肌再灌注损伤的临床研究

对８１例急性心肌梗塞患者行尿激酶１００～１５０万Ｕ静脉溶栓治疗，再通１８例，未通１３例。再通组其溶栓治疗后４、１２、２４和７２小时测定的血浆丙二醛（ＭＤＡ）浓度较溶栓前显著升高（Ｐ＜０．０１），同期测定的血尿酸（ＵＡ）浓度在溶栓治疗后４小时较溶栓前明显升高（Ｐ＜０．０５），未通组的血浆ＭＤＡ和ＵＡ浓度在溶栓前后均无明显变化（Ｐ＞０．０５）。溶栓治疗后４小时血浆ＭＤＡ和ＵＡ浓度的变化，在再通组呈正相关（ｒ＝０．４３，Ｐ＜０．０１），未通组则无相关关系（ｒ＝０．０２７，Ｐ＞０．０５）。说明人体缺血心肌再灌注时有氧自由基（ＯＦＲ）生成。黄嘌呤氧化酶系统是人体ＯＦＲ生成的主要途径。     

缺血后处理对大鼠急性心肌缺血再灌注损伤的影响

目的观察在体条件下缺血后处理对大鼠心肌缺血再灌注损伤的作用及可能的途径。方法建立大鼠在体缺血再灌注模型,将30只大鼠随机分为假手术组、缺血再灌注组、缺血后处理组、缺血预适应组。于再灌注末测定心肌酶,超氧化物歧化酶(SOD)及丙二醛(MDA)的含量,并测定心肌组织梗死面积。结果与缺血再灌注组相比,缺血后处理组与缺血预适应组心肌梗死面积明显减小,血浆肌钙蛋白I及MDA的含量均降低(P<0.05),血浆SOD活性升高(P<0.05)。结论缺血后处理可减轻心肌缺血再灌注损伤,具有心肌保护效应。     

家兔肝缺血再灌注损伤中脂质过氧化反应及人参多糖的干预

目的 观察肝缺血再灌注损伤时脂质过氧化的变化以及人参多糖的干预作用,并探究其机制.方法 30只家兔随机均分为对照组、缺血再灌注组和人参多糖组.观察血浆及肝组织中丙二醛含量及超氧化物歧化酶、谷胱甘肽过氧化物酶、黄嘌呤氧化酶和丙氨酸氨基转移酶活力变化,光镜下观察肝组织结构变化,并观察人参多糖对上述指标的影响.结果 缺血再灌注组血浆超氧化物歧化酶和谷胱甘肽过氧化物酶活力在肝脏缺血45 min以及再灌注45 min逐步降低,丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量明显升高.人参多糖组血浆超氧化物歧化酶和谷胱甘肽过氧化物酶活力与缺血前比无明显下降,丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量无明显升高,尤其再灌注45 min血浆超氧化物歧化酶活力显著高于缺血再灌注组同期(P<0.01),丙氨酸氨基转移酶、黄嘌呤氧化酶活力和丙二醛含量显著低于缺血再灌注组同期水平(P<0.01).肝组织超氧化物歧化酶、谷胱甘肽过氧化物酶活力缺血再灌注组明显低于对照组,人参多糖组则明显高于缺血再灌注组(P<0.01);黄嘌呤氧化酶活力和丙二醛含量缺血再灌注组明显高于对照组(P<0.05或P<0.01),而人参多糖组则明显低于缺血再灌注组(P<0.05或P<0.01).光镜下发现缺血再灌注组肝组织细胞形态学结构明显异常,人参多糖组肝组织损伤明显减轻.结论 人参多糖能降低黄嘌呤氧化酶活性,减少氧自由基的生成,并且能增强超氧化物歧化酶、谷胱甘肽过氧化物酶等抗氧化酶的活性,清除氧自由基,抑制脂质过氧化反应,从而有效减轻肝缺血再灌注损伤.     

活血益心方对大鼠缺血再灌注心肌损伤的保护作用

目的通过对大鼠心肌缺血再灌注损伤模型的研究,观察活血益心方对缺血再灌注心肌损伤的保护作用。方法大鼠随机分组,连续给药10 d,末次给药1 h后除空白组动物外,其余动物结扎左冠脉前降支30 min,再灌注2 h,观察心电图,检测血中心肌酶、丙二醛(MDA)、超氧化物歧化酶(SOD)、谷光甘肽过氧化物酶(GSH-PX)、游离脂肪酸(FFA)、一氧化氮(NO)、内皮素(ET)、白细胞介素(IL)-1、IL-6、肿瘤坏死因子(TNF)-α、C反应蛋白(CRP)活性或含量,心肌Na~+-K~+-ATP、Ca~(2+)-Mg~(2+)-ATP含量。结果活血益心方能明显抑制缺血再灌注损伤大鼠血清肌酸激酶(CK)、天门冬氨酸氨基转移酶(AST)和乳酸脱氢酶(LDH)活性及FFA水平升高,增强SOD、GSH-PX活性;可明显抑制炎性递质IL-1、IL-6和TNF-α激活;明显降低MDA及CRP含量,增加NO含量;明显增强心肌Ca~(2+)-Mg~(2+)-ATP、Na~+-K~+-ATP活力。结论活血益心方对大鼠缺血再灌注心肌损伤具有明显的保护作用。     

卡托普利对缺血再灌注兔心肌一氧化氮及其合酶活性的影响

目的：探讨卡托普利（ｃａｐｔｏｐｒｉｌ）对局部缺血再灌注免心肌保护作用的机制。 方法：将１８只新西兰兔随机分３组（每组ｎ＝６）,对照组左冠状动脉前降支阻断３０分,再灌注９０分;卡托普利组阻断前３０分静脉注射卡托普利每 ２０分 ２ ｍｇ／ｋｇ,再灌注时再持续静脉注射卡托普利每 ９０分１ｍｇ／ｋｇ,假手术组环左冠状动脉前降支置线但不阻断血流。观察心肌一氧化氮合酶（ＮＯＳ）同工酶活性、过氧化物歧化酶活性、丙二醛含量、肌酸激酶含量及右心房血一氧化氮（ＮＯ）的变化,监测心肌功能。 结果：缺血再灌注心肌原生型ＮＯＳ（ＣＮＯＳ）活性（Ｐ＜０．００１）及总ＮＯＳ活性（Ｐ＜０．０１）显著下降,ＮＯ产生减少（Ｐ＜０．０５～０．０１）,卡托普利组缺血再灌注期间ＮＯ水平高于对照组（Ｐ＜０．０１）,再灌注３０分心肌ＣＮＯＳ活性（Ｐ＜０．０１）及总ＮＯＳ活性（Ｐ＜０．０５）显著高于对照组,心肌损害较对照组减轻。 结论：ＮＯ产生不足是心肌再灌注损伤的重要因素,卡托普利通过调节ＮＯＳ活性,维持正常ＮＯ水平起到保护作用。     

Reversal of inducible nitric oxide synthase uncoupling unmasks tolerance to ischemia/reperfusion injury in the diabetic rat heart

The diabetic heart is known to be susceptible to ischemia/reperfusion (I/R) injury by increased oxidative stress. Although oxidative stress upregulates inducible nitric oxide (iNOS), the role of iNOS in I/R injury in the diabetic heart has been poorly understood. Because iNOS-derived nitric oxide (NO) plays a crucial role in cardioprotection against I/R injury, we hypothesized that inhibition of iNOS uncoupling would restore tolerance to I/R injury in the diabetic heart. The present study demonstrated that iNOS-derived superoxide generation was reduced, and that the NO bioavailability was increased, by treatment with the NOS-cofactor, tetrahydrobiopterin (BH4), before I/R in the hearts isolated from diabetic rats. This was associated with a reduction of infarct size and improvement of left ventricular (LV) function after I/R. The cardioprotective effect of BH4 was abrogated by treatment with a thiol reducing agent dithiothreitol (DTT), but not a NO-sensitive guanylyl cyclase inhibitor ODQ, suggesting that iNOS-derived NO-mediated cardioprotection occurs through protein S-nitrosylation but not cGMP-dependent signaling in the diabetic heart. Indeed, protein S-nitrosylation was increased by treatment with BH4 in the diabetic heart and was inhibited by DTT. These results suggest that the inhibition of iNOS uncoupling unmasks tolerance to I/R injury through enhanced protein S-nitrosylation in the diabetic rat heart.     

冠心宁注射液对大鼠缺血再灌注心肌的保护作用研究

目的:探讨冠心宁注射液对大鼠缺血再灌注心肌的影响。方法:40只SD大鼠被随机分为四组,每组10只,分别为:假手术组、梗塞对照组、冠心宁注射液低剂量组、冠心宁注射液高剂量组。采用结扎冠状动脉左前降支的方法复制急性心肌缺血再灌注模型,观察大鼠急性心肌梗塞范围、梗塞心肌组织细胞因子白细胞介素(IL)-10、肿瘤坏死因子(TNF)-α的水平。结果:(1)冠心宁注射液低、高剂量组心肌梗塞范围均显著小于梗塞对照组(P0.01),两剂量组之间无显著差异(P0.05);(2)冠心宁注射液低、高剂量组IL-10水平高于梗塞对照组(P0.05),低于假手术组(P0.01);TNF-α水平低于梗塞对照组(P0.05),高于假手术组(P0.01),而两剂量组之间无显著差异(P均0.05)。结论:冠心宁注射液能抑制大鼠坏死心肌TNF-α的表达,促进IL-10的生成,抑制炎症反应,减少心肌梗塞范围,具有较好的心肌保护作用。     

Lipid peroxidation in nicotinamide-deficient and nicotinamide-supplemented rats with streptozotocin-induced diabetes

Reactive oxygen species have been related to the pathogenesis of various diseases, including diabetes mellitus. Nicotinamide has been used for the prevention of the diabetogenic effects of streptozotocin (STZ) in animals. In the present study we assessed the effect of diets with deficient, normal or 17-fold supplemented nicotinamide concentrations on the rate of lipopoeroxidation in animals with STZ-induced diabetes. Male Wistar rats were divided into three groups kept on one of the diets for six weeks: DD, diabetic rats on a nicotinamide-deficient diet; DN, diabetic rats on a normal nicotinamide diet; and DS, diabetic rats on a nicotinamide-supplemented diet. During the fourth week of the experiment all animals were fasted for 24 hours and injected into the tail vein with a single STZ dose (40 mg/kg weight). Eight animals from each of the six groups were then sacrificed 24 hours, 1 week and 2 weeks after STZ injection. Mean pancreatic thiobarbituric acid reactive substances (TBARS) (nmol/mg tissue) were significantly lower in the DS group (p < 0.05) compared to the DN and DD groups at 24 hours and during the first week. Hepatic TBARS concentrations (nmol/mg protein) did not differ between groups. Mean hepatic reduced glutathione (GSH) levels were significantly higher (46.76 ± 12.33 nmol/mg protein) in the DS group compared to the DD (32.90 ± 6.70) and DN (24.55 ± 6.41) groups, but only after the 24-hour period. Hepatic vitamin E consumption (Μg/g tissue) was considerable in the groups not supplemented with nicotinamide, whereas vitamin E levels were unchanged in the supplemented group. In contrast, plasma vitamin E levels were decreased in the normal and supplemented groups after 1 and 2 weeks. A higher N-methylnicotinamide excretion (μg/ 24 hours) occurred in the supplemented group. We conclude that, after induction of diabetes with STZ, nicotinamide supplementation protected from the damage caused by the toxic action of STZ, promoting lower lipid peroxidation. Received: 27 September 1999 / Accepted in revised form: 3 March 2000     

Ketamine anesthesia reduces intestinal ischemia/reperfusion injury in rats

AIM： To investigate the effects of ketamine anesthesia on the motility alterations and tissue injury caused by ischemia/reperfusion in rats. METHODS： Thirty male Wistar rats weighing 200-250 g were used. Ischemia was induced by obstructing blood flow in 25% of the total small intestinal length （ileum） with a vascular clamp for 45 min, after which either 60 min or 24 h of reperfusion was allowed. Rats were either anesthetized with pento-barbital sodium （50 mg/kg） or ketamine （100 mg/kg）. Control groups received sham surgery. After 60 min of reperfusion, the intestine was examined for mor-phological alterations, and after 24 h intestinal basic electrical rhythm （BER） frequency was calculated, and intestinal transit determined in all groups. RESULTS： The intestinal mucosa in rats that were anesthetized with ketamine showed moderate alterations such as epithelial lifting, while ulceration and hemorrhage was observed in rats that received pento-barbital sodium after 60 min of reperfusion. Quantitative analysis of structural damage using the Chiu scaleshowed significantly less injury in rats that received ketamine than in rats that did not （2.35 ± 1.14 vs 4.58 ± 0.50, P 〈 0.0001）. The distance traveled by a marker, expressed as percentage of total intestinal length, in rats that received pentobarbital sodium was 20% ± 2% in comparison with 25.9% ± 1.64% in rats that received ketamine （P = 0.017）. BER was not statistically different between groups. CONCLUSION： Our results show that ketamine anesthesia is associated with diminished intestinal injury and abolishes the intestinal transit delay induced by ischemia/reperfusion.     

保心丸对大鼠心肌缺血再灌注心律失常的作用

目的观察保心丸对大鼠心肌缺血再灌注心律失常的作用，并探讨其作用机理。方法采用在体大鼠心肌缺血再灌注损伤模型，研究保心丸对再灌注心律失常，心肌超氧化物歧化酶（ＳＯＤ）活性和脂质过氧化产物丙二醛（ＭＤＡ）含量的影响。结果保心丸可明显缩短缺血再灌注心律失常的持续时间，降低室颤的发生率，提高心肌ＳＯＤ活性，降低ＭＤＡ含量。结论保心丸具有抗心肌缺血再灌注心律失常的作用，其机理与抑制脂质过氧化反应有关     

MicroRNA-15a/b are up-regulated in response to myocardial ischemia/reperfusion injury

Objective Several studies have indicated that miR-15a, miR-15b and miR-16 may be the important regulators of apoptosis. Since attenuate apoptosis could protect myocardium and reduce infarction size, the present study was aimed to find out whether these miRNAs participate in regulating myocardial ischemia reperfusion (I/R) injury. Methods Apoptosis in mice hearts subjected to I/R was detected by TUNEL assay in vivo, while flow cytometry analysis followed by Annexin V/PI double stain in vitro was used to detect apoptosis in cultured cardiomyocytes which were subjected to hypoxia/reoxygenation (H/R). Taqman real-time quantitative PCR was used to confirm whether miR-15a/15b/16 were involved in the regulation of cardiac I/R and H/R. Results Compared to those of the controls, I/R or H/R induced apoptosis of cardiomyocytes was significantly increased both in vivo (24.4% ± 9.4% vs. 2.2% ± 1.9%, P < 0.01, n = 5) and in vitro (14.12% ± 0.92% vs. 2.22% ± 0.08%). The expression of miR-15a and miR-15b, but not miR-16, was increased in the mice I/R model, and the results were consistent in the H/R model. Conclusions Our data indicate miR-15 and miR-15b are up-regulated in response to cardiac I/R injury, therefore, down-regulation of miR-15a/b may be a promising strategy to reduce myocardial apoptosis induced by cardiac I/R injury.     

The effects of dietary hempseed on cardiac ischemia/reperfusion injury in hypercholesterolemic rabbits

BACKGROUND: Hempseed is a novel functional food that contains several health-promoting polyunsaturated fatty acids (PUFAs). PUFAs, such as those found in flaxseed and fish, have been shown to protect the heart against arrhythmias following ischemia/reperfusion. OBJECTIVE: TO INVESTIGATE THE POTENTIAL OF DIETARY HEMPSEED AS A CARDIOPROTECTIVE AGENT AGAINST GLOBAL ISCHEMIA AND SUBSEQUENT REPERFUSION BY ASSESSING SEVERAL MEASUREMENTS OF CARDIAC PERFORMANCE: QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration. METHODS: MALE NEW ZEALAND WHITE RABBITS WERE FED ONE OF SIX DIETS: a control diet; or one supplemented with 10% hempseed, 10% delipidated hempseed, 0.5% cholesterol, 0.5% cholesterol plus 10% hempseed or 5% coconut oil. After eight weeks on their respective diets, the hearts were excised and subjected to 30 min of global ischemia and 45 min of reperfusion. Electrocardiogram traces were recorded throughout the experiment and were subsequently analyzed for QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration. Plasma and cardiac tissue were analyzed for fatty acid content and composition. RESULTS: Cholesterol-fed animals exhibited significantly higher PUFA levels in their plasma, but this did not directly translate into higher PUFA levels in their cardiac fractions. There were no significant differences among the groups in the incidence or duration of ischemia-derived arrhythmias. During reperfusion, there was a significant decrease in the incidence of fibrillation in the hearts obtained from cholesterol-fed and hempseed- plus cholesterol-fed rabbits compared with the hearts from delipidated hempseed-fed rabbits. CONCLUSIONS: Dietary hempseed induced limited beneficial effects on cardiac function during ischemia/reperfusion challenge. The present study does not support the use of dietary hempseed to protect the heart during ischemic insult in this experimental model.     

Myocardial protection by co-administration of l-arginine and tetrahydrobiopterin during ischemia and reperfusion

Background

Reduced bioavailability of nitric oxide (NO) is a key factor contributing to myocardial ischemia and reperfusion injury. The mechanism behind the reduction of NO is related to deficiency of the NO synthase (NOS) substrate l-arginine and cofactor tetrahydrobiopterin (BH₄) resulting in NOS uncoupling. The aim of the study was to investigate if the combination of l-arginine and BH₄ given iv or intracoronary before reperfusion protects from reperfusion injury.

Methods

Sprague–Dawley rats and pigs were subjected to myocardial ischemia and reperfusion. Rats received vehicle, l-arginine, BH₄, l-arginine + BH₄ with or without the NOS-inhibitor L-NMMA iv 5 min before reperfusion. Pigs received infusion of vehicle, l-arginine, BH₄ or l-arginine + BH₄ into the left main coronary artery for 30 min starting 10 min before reperfusion.

Results

Infarct size was significantly smaller in the rats (50 ± 2%) and pigs (54 ± 5%) given l-arginine + BH₄ in comparison with the vehicle groups (rats 65 ± 3% and pigs 86 ± 5%, P < 0.05). Neither l-arginine nor BH₄ alone significantly reduced infarct size. Administration of L-NMMA abrogated the cardioprotective effect of l-arginine + BH₄. Myocardial BH₄ levels were 3.5- to 5-fold higher in pigs given l-arginine + BH₄ and BH₄ alone. The generation of superoxide in the ischemic-reperfused myocardium was reduced in pigs treated with intracoronary l-arginine + BH₄ versus the vehicle group (P < 0.05).

Conclusion

Administration of l-arginine + BH₄ before reperfusion protects the heart from ischemia–reperfusion injury. The cardioprotective effect is mediated via NOS-dependent pathway resulting in diminished superoxide generation.     

白花前胡丙素对心肌缺血再灌注损伤的影响

目的观察白花前胡丙素（Pra—C）对抗大鼠心肌缺血再灌注损伤（MI／R）的机制及其保护作用。方法48只健康雄性SD大鼠随机分为6组：假手术组（A组）、缺血再灌注组（B组）、溶剂±缺血再灌组（C组）、Pra—C5mg／kg组（D组）、Pra—C15mg／kg组（E组）和Pra—C30mg／kg组（F组）。Pra—C各剂量组分别于实验前3d腹腔注射,每天2次,于实验前2h加强1次;A组给予等量的生理盐水腹腔注射;B组采用冠状动脉左前降支结扎40min,再灌120min建立;C组给予等量的50％PEG400,10ml／kg溶剂腹腔注射。分光光度计法检测心肌组织SOD活性和MDA含量。苏木素-伊红（HE）染色观察心肌组织病理改变,透射电镜观察心肌超微结构的变化,并比较各组之间的差异。结果六组SOD值（U／mgprot）分别为154．78±10．94、78．16±7．13、79．15±7．12、88．77±8．53、115．80±7．09和145．07±7．24;MDA值（nmol／mgprot）分别为2．70±0．26、6．77±0．23、6．48±0．64、5．07±0．38、3．41±0．32和2．72±0．32。B组和C组心肌组织SOD活性和MDA含量差异无统计学意义（P〉0．05）;与它们相比较,D、E、F组SOD活性显着增加（P〈0．05或P〈0．01）,MDA含量显著降低（P〈0．01）。D、E、F组心肌组织的病理改变有不同程度的减轻。结论Pra—C可以减轻MI／R对心肌组织的损伤作用。其机制可能与对抗氧自由基、对抗脂质过氧化有关。