Activation of μ-opiate receptors as a factor of regulation of heart resistance to ischemia-reperfusion and oxidative stress

Intravenous injection of the selective μ-opiate receptor agonist DAMGO (0.1 mg/kg, 15 min before isolation of the heart) improved resistance of isolated perfused rat heart to ischemia (45 min) and reperfusion (60 min) damages.In vivo administration of DAMGO prevented reperfusion-induced damages to cardiomyocytes and decreased the content of conjugated dienes in the myocardium during ischemia-reperfusionin vitro. Furthermore, stimulation of μ-opiate receptors promoted recovery of myocardial contractility during reoxygenation, but had no effect on heart resistance to free radical-induced damages during perfusion of isolated heart with a solution containing Fe²⁺ and ascorbic acid. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 163–167, August, 2000     

脑缺血再灌流对大鼠海马FOS蛋白的诱导及电针对其的影响

目的　探讨脑缺血再灌流后电针对大鼠海马FOS蛋白表达的影响。方法　采用夹闭大鼠双侧颈总动脉造成的脑缺血再灌流损伤模型 ,电针“百会”、“风池”、“大钟”及“足三里”穴 ,频率 2～ 2 0Hz,强度以肌肉轻微抖动为准 ,持续 30min ,4h后观察海马FOS蛋白的表达。结果　电针能明显加强脑缺血再灌流后海马各区FOS蛋白的表达。结论　缺血再灌流可诱导海马FOS蛋白的显著表达 ;电针信息对缺血后海马神经元的功能可能会有影响。     

肢体缺血/再灌注后氧自由基与Bax蛋白、细胞凋亡的关系

目的　阐明氧自由基与Bax蛋白、细胞凋亡在大鼠肢体缺血 /再灌注不同时相中的变化规律及相互关系。方法　采用大鼠股动脉夹闭模型 ,阻断股动脉血流 5h后再灌注 ,设立缺血组、再灌注组 ,再灌注组设立 1,6 ,12 ,2 4h 4个检测时相 ,应用硫代巴比妥酸法测定肌肉组织中脂质过氧化产物丙二醛 (MDA)水平 ,应用免疫组化方法测定Bax蛋白表达的变化 ,应用原位末端标记法及电镜方法观察细胞凋亡现象。结果　随着再灌注时间的延长 ,MDA水平、Bax蛋白表达强度、细胞凋亡指数 (AI)进行性升高 ,且三者呈显著正相关。结论　氧自由基与细胞凋亡同时参与肢体再灌注损伤 ,氧自由基可能通过调节Bax蛋白表达促进细胞凋亡的发生。     

Peroxisomal fatty acid oxidation capacity is more resistant to ischaemic and reperfusion injury than mitochondrial fatty acid oxidation capacity in feline hearts

We investigated ischaemic and postischaemic mitochondrial and peroxisomal fatty acid oxidation capacity, ATP levels and regional function in 40 anaesthetized open chest cats subjected to 10 or 40 min of regional myocardial ischaemia with or without 3 h of reperfusion (n=10 in each situation). Following 10 min of ischaemia, the mitochondrial fatty acid oxidation capacity measured in tissue extracts from ischaemic tissue (nmol min^-1 mg protein^-1) was reduced in both subepi- and subendocardium, but was normalized in reperfused tissue extracts from both wall layers (0.29±0.03 and 0.30±0.04 vs. 0.57±0.05 and 0.59±0.05, P<0.05). Peroxisomal fatty acid oxidation capacity in tissue extracts was unaffected by ischaemia and reperfusion. ATP levels and regional function measured in the LAD region was partly restored transmurally. After 40 min of LAD occlusion, mitochondrial fatty acid oxidation capacity was reduced, with higher activity in subepi- than in subendocardium (0.27±0.05 vs. 0.19±0.04, P<0.05). Reperfusion did not restore mitochondrial fatty acid oxidation capacity. Peroxisomal fatty acid oxidation capacity was increased in the ischaemic subendocardium compared with levels in non-ischaemic subendocardium (0.53±0.02 vs. 0.45±0.03, P<0.05), with normalization at the end of reperfusion. ATP levels were non-uniformly reduced during ischaemia and not repleted during reperfusion. Regional function recovered in circumferential segments but not in longitudinal segments following 40 min of ischaemia. In conclusion fatty acid oxidation enzymes seem to be more resistant to ischaemia in peroxisomes than in mitochondria. Mitochondrial fatty acid oxidation is fully reversible following shortlasting ischaemia, but remains depressed following prolonged ischaemia and reperfusion.     

Hyperbaric oxygenation mitigates focal cerebral injury and reduces striatal dopamine release in a rat model of transient middle cerebral artery occlusion

The usefulness of the administration of hyperbaric oxygen (HBO) in the treatment of acute focal cerebral ischemia remains debatable. A significant association exists between focal cerebral injury and an excessive release of extracellular dopamine (DA). In vivo microdialysis was used in the present study to examine the effect of HBO on DA release in the striatum during ischemia and reperfusion in rats. The histological changes occurring were also evaluated. Focal cerebral ischemia was induced by occlusion of the middle cerebral artery (MCA) using a surgically placed intraluminal filament. Control rats (n=8) were subjected to 1 h of ischemia, whilst the study rats (n=8) were in addition treated with HBO (2.8 atmospheres of absolute pressure 100% O₂) during ischemia. Both groups were returned to breathing room air at normal pressure during reperfusion. Microdialysis samples were continuously collected at 15 min intervals at 2 μl·min^–1. The [mean (SE)] increase in release of striatal DA attained significance after 30 min of occlusion of MCA [170 (24)%], and continued to increase [268 (26)% at 45 min] reaching a peak level at 60 min [672 (59)%] before returning to the baseline level during the late reperfusion phase. There was no significant change in the level of DA in HBO treated rats during the period of ischemia. A significant reduction in edema and neuronal shrinkage were observed by histological examination in HBO treated rats when compared to the control rats. The results showed that HBO, when administered during ischemia, offered significant neuroprotection in our experimental model of transient focal cerebral ischemia in the rat. The mechanism seems to imply, at least in part, a reduced level of DA. Electronic Publication     

茶黄烷醇对离体缺血再灌注鼠心心律失常的作用

本研究旨在探讨茶黄烷醇(TF)对离体缺血再灌注鼠心心律失常的作用。结果表明,对照组缺血后再灌注初期心律失常发生率高达91.67%(11/12),显著高于TF组(P<0.005),TF组心律失常发生率仅为23.08%(3/13);对照组心律失常持续时间平均为27.91±6.94min,TF组平均为9.83±6.21min,两组比较差异显著(P<0.001)。上述结果表明TF具有显著的抗缺血再灌性心律失常作用。     

Relationship between ischaemic time and ischaemia/reperfusion injury in isolated Langendorff‐perfused mouse hearts

Myocardial functional recovery and creatine kinase (CK) release following various periods of ischaemia were investigated in isolated mouse hearts. The hearts were perfused in the Langendorff mode with pyruvate‐containing Krebs–Hensleit (KH) buffer under a constant perfusion pressure of 80 mmHg, and were subjected to either continuous perfusion or to 5, 15, 20, 25, 30, 45 or 60 min of global ischaemia followed by 45 min of reperfusion. In hearts subjected to ischaemic periods of 5, 15 or 20 min, there was a transient reduction in the left ventricular (LV) dP/dt max during the early phase of reperfusion, while the recovery at the end of reperfusion reached a level similar to that in hearts subjected to continuous perfusion. In hearts subjected to longer ischaemic periods, i.e. 25, 30, 45 or 60 min, the decrease in the cardiac performance was more pronounced and persistent, with significantly lower recovery in LV dP/dt max and higher LV end diastolic pressure (LVEDP) at the end of reperfusion than in the non‐ischaemic hearts. There were no significant differences in the recoveries in coronary flow or in heart rate (HR) between groups. Similarly to the functional recovery, the release of CK showed a clear ischaemic length‐related increase. In conclusion, the Langendorff‐perfused isolated mouse heart could be a valuable model for studies of myocardial ischaemia/reperfusion injury. Future studies using gene‐targeted mice would add valuable knowledge to the understanding of myocardial ischaemia/reperfusion injury.     

内洋地黄素拮抗剂上调缺血再灌注损伤大鼠心肌细胞膜钠泵亚基的表达

目的： 观察内洋地黄素特异性拮抗剂地高辛抗血清对心肌缺血再灌注（MIR）损伤大鼠心肌组织内洋地黄素水平、钠泵活性、线粒体总钙浓度以及钠泵各亚基基因表达的影响，探讨内洋地黄素在心肌缺血再灌注损伤中的作用及其机制。方法: 将56只雄性SD大鼠随机分成7组，每组8只。假手术对照组（sham）：丝线穿过左冠状动脉前降支，但不结扎；缺血再灌注组（MIR）：结扎左冠状动脉前降支30 min，再灌注45 min；生理盐水组（NS）、维拉帕米组（Ver）、小剂量、中剂量、大剂量地高辛抗血清组（ADA）：于再灌注前5 min经股静脉分别注射生理盐水、维拉帕米5 mg·kg^-1、地高辛抗血清8.6 mg·kg^-1、 17.3 mg·kg^-1、34.5 mg·kg^-1，容积均为5 mL·kg^-1，5 min内注射完毕，其余同MIR模型组。再灌注结束后，立即取缺血区左室心肌检测心肌匀浆内洋地黄素水平、心肌细胞膜Na+ K+_ATP酶和Ca2+_Mg2+_ATP酶活性、线粒体总钙浓度；分别采用RT-PCR及Western blotting方法和免疫组化方法检测心肌钠泵α₁、α₂、α₃和β₁亚基mRNA及蛋白水平基因表达的改变。结果: 心肌缺血再灌注损伤时，心肌组织内洋地黄素水平明显升高，心肌细胞膜钠泵和Ca2+_Mg2+_ATP酶活性显著下降，线粒体总钙浓度升高，钠泵α₁、α₂、α₃和β₁亚基在mRNA及蛋白水平基因表达均明显下降；维拉帕米除具有降低线粒体总钙浓度外，对其它各项指标无明显影响。地高辛抗血清呈剂量依赖性地显著降低心肌组织内洋地黄素水平，恢复细胞膜钠泵和Ca2+_Mg2+_ATP酶活性，降低线粒体总钙浓度，上调钠泵α₁、α₂、α₃和β₁亚基mRNA及蛋白水平的基因表达。结论: 心肌缺血再灌注促进机体内洋地黄素分泌增加，后者通过下调心肌细胞膜上的钠泵α₁、α₂、α₃和β₁亚基基因表达抑制钠泵活性，进而抑制Ca2+_Mg2+_ATP酶活性，导致线粒体内钙超载，介导心肌缺血再灌注损伤。内洋地黄素特异性拮抗剂地高辛抗血清通过阻断内洋地黄素的生物学作用，上调钠泵各亚基的基因表达，发挥其抗心肌缺血再灌注损伤的作用。     

大鼠肝缺血再灌注损伤对心脏能量代谢和结构的影响及其机制

目的：探讨肝缺血再灌注损伤对心脏能量代谢和结构的影响及其可能的发生机制。方法：健康雄性Wistar大鼠48只，随机分为对照组、缺血30 min组（I组）及缺血30 min再灌注即刻组、2 h组、4 h组和6 h组（I/R组、I/R 2 h组、I/R 4 h组和I/R 6 h组），每组8只。用偶氮显色法测定血清中的内毒素，用放射免疫法测定心肌组织胰岛素和胰岛素抗体，取心肌制备组织匀浆测丙二醛（MDA）、髓过氧化物酶（MPO），乳酸含量。 结果：在肝缺血再灌注损伤过程中，内毒素在I组和I/R组达到高峰，随着再灌注时间的延长逐渐下降，但仍高于对照组（P<0.05）。I组及I/R各组MDA的含量明显高于对照组，在I/R 2 h组、I/R 4 h组、I/R 6 h组差别更为明显（P＜0.05）；再灌注各组MPO活性明显高于对照组、I组（P＜0.05）；随着再灌注时间的延长，心肌组织中乳酸含量明显增加（P＜0.05），但在I/R 6 h组呈下降趋势（P＜0.05）；胰岛素的含量在I/R 4 h组和I/R 6 h组明显下降（P＜0.05）；而胰岛素抗体在各组间无显著差异（P＞0.05）。结论：肝缺血再灌注损伤过程中，肠源性内毒素吸收入血及肝脏解毒功能的降低所致的内毒素血症可能是引起心脏能量代谢和结构改变的始动环节。