灯盏花素对大鼠心肌缺血再灌注损伤诱导细胞凋亡的影响

目的观察灯盏花素（BRE）对大鼠心肌缺血再灌注（I/R）诱导细胞凋亡及凋亡相关基因Bcl-2、Bax表达的影响,并对其作用机制进行初步探讨。方法30只SD大鼠随机分为3组（n=10）:①假手术（Sham）组:前降支穿线不结扎,观察1.5 h;②缺血再灌注（I/R）组:结扎前降支30 m in,再灌注前5 m in生理盐水（4 mg/kg）iv,再灌注1h;③BRE组:再灌注前5 m in应用BRE（4 mg/kg）iv,余同I/R组。常规方法检测丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性,免疫组化法测定Bc l-2、Bax蛋白的表达,通过细胞图像分析系统测量细胞阳性染色面积百分率,应用透射电镜观察心肌超微结构的变化。结果同I/R组相比,BRE组心肌组织MDA含量显著降低[（7.56±1.67）μmol/gvs（16.58±2.59）μmol/g,P<0.05],SOD活性显著升高[（2.37±0.22）mkat/gvs1.38±0.14 mkat/g,P<0.05],Bax蛋白表达显著降低（5.02±1.01vs18.59±5.68,P<0.01）,而Bc l-2蛋白表达显著增高（17.48±4.72vs7.32±2.05,P<0.01）,Bax/Bc l-2显著降低（0.29±0.57vs3.32±0.10,P<0.01）,细胞阳性染色面积百分率显著减少（0.42±0.06vs13.84±1.97,P<0.01）,细胞超微结构损伤明显减轻。结论BRE通过调控Bax/Bc l-2表达抑制心肌I/R诱导的细胞凋亡,对缺血再灌注心肌具有保护作用。     

丙泊酚预处理与缺血预处理保护大鼠体外心脏缺血再灌注损伤作用的比较

目的:以缺血预处理(IPC)为标准观察丙泊酚预处理对大鼠体外心脏再灌注损伤的保护作用并探索其可能机制。方法:建立大鼠体外心脏Langendorff灌流模型并随机分为对照组(A组, n=8)、丙泊酚预处理组(B组,n=6)、IPC组(C组,n=6)及5 羟癸酸(5 HD)对照组(D组,n=8)、5 HD加丙泊酚预处理组(E组,n=6)、5 HD加 IPC组(F组,n=7)共6组。连续记录各组心脏血流动力学指标及冠状动脉流量变化,进行再灌注性心律失常评分,并计算心脏梗死面积。结果:B、C、E组血流动力学指标、冠状动脉流量、心律失常评分、梗死面积显著优于A组,以C组最显著(P<0.01或0.05),而D、F组与A组比较差异无统计学意义。结论:丙泊酚预处理与 IPC均可改善体外大鼠心脏再灌注所致的血流动力学紊乱、冠状动脉循环受损及再灌注性心律失常的发生,并缩小心脏梗死面积,但丙泊酚上述保护效应较 IPC弱。阻滞线粒体 KATP通道开放对丙泊酚预处理作用无影响,推测该通道与其保护效应无关。     

Benznidazole prevents endothelial damage in an experimental model of Chagas disease

ObjectivesTo evaluate the effect of benznidazole on endothelial activation in a murine model of Chagas disease.MethodsA low (30 mg/kg/day) and a high (100 mg/kg/day) dose of benznidazole were administered to mice infected with Trypanosoma cruzi during the early phases of the infection. The effects of the treatments were assessed at 24 and 90 days postinfection by evaluating the parasitaemia, mortality, histopathological changes and expression of ICAM in the cardiac tissue. The blood levels of thromboxane A₂, soluble ICAM and E-selectin were also measured. T. cruzi clearance was assessed by the detection of parasite DNA in the heart tissue of infected mice.ResultsBenznidazole decreased the cardiac damage induced by the parasite, and amastigote nests disappeared at 90 days postinfection. Both doses cleared the parasite from the cardiac tissue at 24 and 90 days postinfection. In addition, benznidazole decreased the thromboxane levels and normalized the plasma sICAM and sE-selectin levels by 90 days postinfection.ConclusionsEarly administration of benznidazole at a dose as low as 30 mg/kg eradicates T. cruzi from cardiac tissue. Additionally, benznidazole prevents cardiac damage and modulates endothelial activation as part of its antichagasic activity.     

Preventive mechanism of genistein on coronary endothelial dysfunction in ovariectomized rats: an isolated arrested heart model

The effects of genistein on coronary endothelial dysfunction in bilateral ovariectomized rats were examined. Female Wistar rats were subjected to a bilateral ovariectomy (OVX rat). The animals were divided into three groups: sham treated with vehicle (DMSO 100 microl/day, Sham-DMSO), OVX treated with vehicle (DMSO 100 microl/day, OVX-DMSO), and OVX treated with genistein (0.25 mg/kgBW/day, OVX-genistein). Mean arterial pressure (MAP), heart rate (HR), body weight (BW), uterine weight and plasma E2 were monitored at 4- and 10-week after the treatment. We investigated the endothelium-dependent and -independent vasorelaxation by using acetylcholine (Ach 10(-5) M) and sodium nitroprusside (SNP 10(-7) M), respectively. The experimental results indicated that the uterine weights of all OVX rats were significantly decreased as compared to the sham groups. HR and MAP of both OVX-DMSO and OVX-genistein on 4 and 10 weeks were no significantly increased as compared to the Sham groups. The present coronary vasodilatation responses demonstrated only the significant decrement of endothelium-dependent, not for endothelium-independent, in OVX rats. The treatment of genistein could significantly attenuate this abnormality (% changes of vessel diameter obtained after Ach 10(-6) M: Sham-DMSO(10-wk) = 10.96 +/- 1.2%, OVX-DMSO(10-wk) = 3.2 +/- 0.77%, OVX-genistein(10-wk) = 11.45 +/- 1.85%), (% changes of vessels diameter obtained after SNP 10(-7)M: Sham-DMSO(10-wk) = 16.05 +/- 2.82%, OVX-DMSO(10-wk) = 12.73 +/- 2.72%, OVX-genistein(10-wk) = 16.4 +/- 4.71%) (p < 0.05). However, the lipid profiles monitored from all groups of 4 and 10 weeks did not demonstrate any significant changes. Therefore, it implied that endothelial dysfunction was not primarily cause by the lipid profiles changing in ovariectomized rats. Moreover, such effects of estrogen lacking on coronary endothelial-dependent vasodilatation could be attenuated by genistein supplementation. The present findings suggest that genistein might be used as an therapeutic agent for preventing the menopausal vascular complications.     

Acute effects of cyclosporin and cremophor EL on endothelial function and vascular smooth muscle in the isolated rat heart

Summary We studied the effects of cyclosporin dissolved in the vehicle used as an intravenous preparation, namely, cremophor EL, and cremophor alone on the basal coronary flow plus endothelial function and vascular smooth muscle response by examining their influence on 5-hydroxytryptamine (5-HT) and nitroglycerine (GTN) induced changes in coronary flow in the isolated rat heart. A total of 72 rat hearts were perfused with a modified Langendorf preparation. There was a 12.8±3% reduction in the basal coronary flow after 60 minutes of perfusion with the drug-free buffer (p=ns). A dose of 50 ng/ml of cremophor or cyclosporin gave a similar reduction in the flow (cremophor 9.2±0.7%, cyclosporin 12.7±2%). However, at higher concentrations cremophor caused dose-dependent coronary vasodilation, while cyclosporin had the opposite effect. The maximum effect after 1000 ng/ml of cyclosporin was a 48.7±0.6% decrease, and after an equivalent dose of cremophor a 24.8±2.2% increase in the flow. The vasodilatory response to 5-HT and GTN remained unchanged after 60 minutes of perfusion with the drug-free buffer (5-HT, before 33.3±2.5%, after 37.7±4.2%; GTN, before 34.3±2.5%, after 33.7±1.5%). A period of 60 minutes of perfusion with 500 ng/ml and 1000 ng/ml of cremophor caused a significant reduction in the 5-HT response without an appreciable change in the effect of GTN (500 ng/ml—5-HT, before 29.9±0.9% after 10.7±3.7%; GTN, before 32.3±1.9% after 31.8±3.5%; 1000 ng/ml—5-HT, before 29.7±0.6%, after 12.3±2.7%; GTN, before 33.3±2.8%, after 32.7±1.4%; p<0.001). The same concentration of cyclosporin not only reduced the 5-HT response but also reduced the vasodilation induced by GTN (500 ng/ml—5-HT, before 35.3±3.7%, after 1.6±5%; GTN, before 30.8±1.5%, after 11.2±2.7%; 1000 ng/ml—5-HT, before 32.8±1.9%, after -32.3±1.1%; GTN, before 35.7±0.8%, after 10.0±1.3%). We conclude that cremophor EL causes endothelial dysfunction in the isolated rat heart, and this effect may be aggravated by cyclosporin dissolved in cremophor. Cyclosporin with cremophor also leads to injury to vascular smooth muscle. The direct effect of cremophor is to cause coronary vasodilation, while cyclosporin causes dose-dependent coronary vasoconstriction.     

辛伐他汀对脓毒症大鼠肺组织诱导型一氧化氮合酶表达的影响

目的:探讨辛伐他汀对脓毒症大鼠肺组织诱导型一氧化氮合酶(iNOS)表达的影响.方法:90只健康SD大鼠随机分为对照组(生理盐水2 mL静脉滴注)、内毒素(LPS)组(LPS 5 mg/kg,用生理盐水稀释至2 mL静脉滴注)、LPS+辛伐他汀(Sta)组(LPS 5mg/kg,Sta 20mg/kg,生理盐水稀释至2 mL静脉滴注),每组30只.分别在用药后2、4、6、12、24 h处死大鼠,取右肺下叶用RT-PCR法检测肺组织iNOS mRNA表达.结果:光镜下对照组各时点肺泡结构正常;LPS组2h出现炎症损伤,以6h最为显著;LPS+ Sta组中性粒细胞浸润较LPS组减轻.LPS组iNOSmRNA表达较对照组和LPS+ Sta组明显增高(均P＜0.05),6h达高峰,12 h开始下降;LPS+ Sta组各时点iNOSmRNA表达趋势同LPS组,但接近对照组水平(P＞0.05).结论:辛伐他汀能改善脓毒症时肺组织的病理性炎症损伤,辛伐他汀能减低脓毒症时肺组织iNOS mRNA的表达.     

白藜芦醇预处理对体外大鼠心肌缺血再灌注损伤的保护作用

目的:观察白藜芦醇预处理对体外大鼠缺血再灌注心肌损伤的保护作用及其作用机制。方法:利用Langendorff灌注系统,建立体外大鼠心肌常温全心心肌缺血30min再灌注120min损伤模型。将56只雄性SD大鼠随机分为4组(每组14只):缺血再灌注损伤(IRI)组、白藜芦醇组、Nω硝基L精氨酸甲酯(LNAME)组、氨基胍(AG)组。检测各组的心功能、心肌一氧化氮合酶(NOS)同工酶(NOSi)活性、一氧化氮(NO)的含量、丙二醛的含量、心肌梗死面积以及心肌细胞凋亡指数。结果:与IRI组相比,白藜芦醇组左室发展压(LVDP)、左室压力上升和下降最大变化速率(±dp/dtmax)明显改善(P<0.05或0.01);心肌梗死面积、心肌细胞凋亡指数、心肌丙二醛含量显著降低(P<0.01);心肌NOSi活性和NO含量显著升高(P<0.01)。LNAME组和AG组LVDP和±dp/dtmax显著低于白藜芦醇组(P<0.05或P<0.01);心肌梗死面积、心肌细胞凋亡指数、心肌丙二醛含量显著升高(P<0.01);心肌NOSi活性和NO含量显著降低(P<0.01)。结论:白藜芦醇对体外大鼠IRI具有保护作用,其机制可通过提高心肌NOSi活性,促进NO产生而介导的。     

High pre-ischemic fatty acid levels decrease cardiac recovery in an isolated rat heart model of donation after circulatory death

RationaleDonation after circulatory death (DCD) could improve cardiac graft availability. However, strategies to optimize cardiac graft recovery remain to be established in DCD; these hearts would be expected to be exposed to high levels of circulatory fat immediately prior to the inevitable period of ischemia prior to procurement.ObjectiveWe investigated whether acute exposure to high fat prior to warm, global ischemia affects subsequent hemodynamic and metabolic recovery in an isolated rat heart model of DCD.Methods and ResultsHearts of male Wistar rats underwent 20 min baseline perfusion with glucose (11 mM) and either high fat (1.2 mM palmitate; HF) or no fat (NF), 27 min global ischemia (37 °C), and 60 min reperfusion with glucose only (n = 7–8 per group). Hemodynamic recovery was 50% lower in HF vs. NF hearts (34 ± 30% vs. 78 ± 8% (60 min reperfusion value of peak systolic pressure*heart rate as percentage of mean baseline); p < 0.01). During early reperfusion, glycolysis (0.3 ± 0.3 vs. 0.7 ± 0.3 μmol*min^− 1*g dry^− 1, p < 0.05), glucose oxidation (0.1 ± 0.03 vs. 0.4 ± 0.2 μmol*min^− 1*g dry^− 1, p < 0.01) and pyruvate dehydrogenase activity (1.8 ± 0.6 vs. 3.6 ± 0.5 U*g protein^− 1, p < 0.01) were significantly reduced in HF vs. NF groups, respectively, while lactate release was significantly greater (1.8 ± 0.9 vs. 0.6 ± 0.2 μmol*g wet^− 1*min^− 1; p < 0.05).ConclusionsAcute, pre-ischemic exposure to high fat significantly lowers post-ischemic cardiac recovery vs. no fat despite identical reperfusion conditions. These findings support the concept that oxidation of residual fatty acids is rapidly restored upon reperfusion and exacerbates ischemia–reperfusion (IR) injury. Strategies to optimize post-ischemic cardiac recovery should take pre-ischemic fat levels into consideration.     

Anisotropy and reentrant ventricular tachycardia: experimental model in the isolated rabbit heart

The purpose of this study was to study the role of anisotropic distribution of conduction velocity in the initiation and perpetuation of ventricular tachycardia in an experimental model of sustained reentrant ventricular tachycardia in the Langendorff perfused rabbit heart. The hearts of 30 rabbits were used in the study. The right ventricle, the interventricular septum and the endocardial and intramural layers of the left ventricle were destroyed by freezing. In the surviving epicardial layer an obstacle was created using a cryoprobe. Thus, the final preparation consisted of a perfused ring of epicardium in the left ventricle. In 27 of 30 experiments programmed electrical stimulation induced sustained reentrant excitation around the obstacle. The cycle length of the tachycardia ranged from 128 to 197 ms in different experiments (mean 162 +/- 17 ms). During tachycardia in some segments of the ring the impulse propagated parallel to fiber orientation at a mean conduction velocity of 61 +/- 7 cm/s whereas in other segments of the ring the impulse propagated perpendicular to fiber orientation at a mean conduction velocity of 22 +/- 4 cm/s. An excitable gap was present during all episodes of tachycardia. In conclusion, conduction velocity during reentrant tachycardia depends on the relation between direction of propagation and fiber orientation. This anisotropic distribution of conduction velocity can play an important role in the initiation and perpetuation of ventricular tachycardia.     

Effects of adrenomedullin on the cardiac performance and coronary flow in an isolated perfused rat heart model

The effect of adrenomedullin (AM) on the cardiac performance and coronary flow were studied in an isolated perfused rat heart model based on the modified Langendorff method. The heart rate (HR), electrocardiogram (ECG), left ventricular contraction (LVC) (dP/dt), and coronary flow (CF) were measured before and after the application of AM. The effect of AM on the coronary flow was examined in the model with and without endothelial degradation, using different inhibitors such as N(G)-nitro-L-arginine, glibenclamide, and indomethacin. The present results indicated that AM increased HR and CF, but decreased LVC significantly, while it had no effect on ECG. The vasodilatory effect of AM was discussed in views of endothelial-dependence due to nitric oxide and K+ channel activation.     

Effect of hypoxia on endothelial morphology and interendothelial junctions in the isolated perfused rat heart

Isolated perfused rat hearts were used to assess the effect of 30 or 60 mins of hypoxia on the ultrastructure of the capillary endothelium and particularly on the interendothelial junctions. Perfusions were carried out both in the presence and absence of albumin. Albumin had no effect on ultrastructure or membrane spacing in the interendothelial clefts, neither in oxygenated controls nor in hypoxic hearts. After 30 and 60 mins of hypoxia some capillaries showed endothelial swelling while after 60 mins the endothelium of others was attenuated. The wide regions of the intercellular cleft were not affected by hypoxia but the "narrow zone" gap between membranes became significantly smaller. We conclude that factors within the clefts other than the "tightness" of the narrow zones are responsible for changes in permeability in hypoxia and with albumin.     

Protective effects of regulatory amino acids on ischemia-reperfusion injury in the isolated perfused rat liver

OBJECTIVE: Some amino acids (AAs) display potent regulatory activities on cell metabolism, including via anti-oxidative defences. The aim of this study was to evaluate the protective effect of these AAs on warm ischaemia-reperfusion (I/R) injury in the isolated perfused rat liver. MATERIAL AND METHODS: Livers from fasted male Sprague-Dawley rats were isolated and perfused without (control group) or with (AP group) a mixture of regulatory AAs (glutamine, histidine, leucine, methionine, proline, phenylalanine, tryptophan and alanine). After 45 min of perfusion, warm ischaemia was induced for 45 min by clamping the portal vein catheter; thereafter, reperfusion was performed for 30 min. RESULTS: TNF-alpha production was significantly lower in the AP group during reperfusion (Control: 39+/-7 versus AP: 16+/-2 pg min-1 g-1, p<0.05), and lactate dehydrogenase (LDH) release decreased significantly during the last 15 min of reperfusion (Control: 0.13+/-0.03 versus AP: 0.04+/-0.02 IU min-1 g-1, p<0.05), despite similar levels of oxidative stress. The addition of regulatory AAs was not associated with variations in portal flow, bile flow, hepatic glucose or urea metabolism. However, significant changes in intrahepatic glutamine (Control: 1.4+/-0.2 versus AP: 2.6+/-0.5 micromol g-1, p < 0.05) together with higher glutamate release in the AP group (Control: 10.2+/-5.4 versus AP: 42.6+/-10.9 nmol min-1 g-1, p < 0.05) indicated modifications in nitrogen metabolism. CONCLUSIONS: Taken together, the lower TNF-alpha production, suggesting decreased inflammatory response, the decrease in LDH release in the AP group, demonstrating a better preservation of liver viability, and the increase in hepatic glutamine indicate that AAs play an important role in the liver's response to I/R.     

缺血预处理减轻肥厚心肌缺血再灌注损伤及其信号途径

目的探讨缺血预处理(IPC)对肥厚心肌体外缺血再灌注(IR)损伤的影响及其信号机制。方法48只心肌肥厚大鼠随机分为4组:IR对照组I、PC组I、PC加磷脂酰肌醇-3激酶(PI3K)抑制剂Wortmannin处理组、Wortmannin处理对照组,观察IPC对心肌肥厚大鼠体外IR心脏左心室收缩压、冠状动脉流量、肌酸磷酸激酶(CPK)和乳酸脱氢酶(LDH)释放、心肌梗死范围以及心肌蛋白激酶B(Akt)、糖原合成酶激酶-3β(GSK-3β)磷酸化的影响。结果与IR对照组比较,IPC组心脏左心室收缩压、冠状动脉流量显著提高,CPK、LDH释放减少,心肌梗死范围减小,心肌Akt、GSK-3β磷酸化水平增高,Wortmannin能够抑制IPC所致的Akt、GSK-3β磷酸化,但只能部分消除IPC的心脏保护效应。结论IPC能够减轻心肌肥厚大鼠体外心脏IR损伤,PI3K、Akt、GSK-3β信号途径参与介导IPC对体外IR肥厚心肌的保护作用。     

A possible role of noradrenaline in the development of myocardial infarction: an experimental study in the isolated rat heart

Isolated rat hearts were perfused with buffer containing noradrenaline 10(-7) to 10(-4) M. A dose-dependent depletion of glycogen and ATP were seen together with a leakage of ASAT and creatine phosphokinase (CK). The damage induced by noradrenaline could be prevented by addition of a beta-blocker (metoprolol), verapamil, or lidocaine to the perfusion medium. When the endogenous myocardial stores of noradrenaline are rapidly depleted by perfusion with tyramine a similar cell damage was demonstrated. Electron micrographs from hearts subjected to noradrenaline showed three different types of cell damage that could be correlated to earlier described findings. The importance of noradrenaline for the ischemic injury was demonstrated. It was hypothesized that acute myocardial infarction may start because of a sudden release of endogenous noradrenaline.     

Regulation of endothelial cell adhesion molecule expression in an experimental model of cerebral malaria

OBJECTIVE: Plasmodium falciparum malaria in humans and animal models of this disease have revealed changes in the infected host that are consistent with a systemic inflammatory response. Although it has been proposed that endothelial cell adhesion molecules (CAM) contribute to the adhesive interactions of Plasmodium-infected erythrocytes and immune cells with vascular endothelial cells, ECAM expression has not been systematically studied in Plasmodium-infected animals. METHODS: In this study, the dual radiolabeled monoclonal antibody method was used to quantify the expression of different ECAMs (ICAM-1, VCAM-1, P-selectin, E-selectin) in different regional vascular beds of Plasmodium berghei ANKA-inffected mice (PbA), a well-recognized model of human cerebral malaria. The roles of T lymphocytes and certain cytokines (TNF-alpha, IL-12, IFN-gamma) in mediating the infection-induced expression of ICAM-1 and P-selectin were assessed by using relevant mutant mice. RESULTS: Wild-type (WT) mice exhibited highly significant increases in the expression of ICAM-1, VCAM-1, and P-selectin (but not E-selectin) in all vascular beds on the 6th day of PbA infection. The PbA-induced upregulation of ICAM-1 was significantly blunted in mice that were either deficient in IFN-alpha, IL-12 (but not TNF1b) or T lymphocytes (Rag-1 deficiency); however, these responses were tissue specific. CONCLUSIONS: These findings indicate that vascular endothelial cells in most regional circulations assume an inflammatory phenotype and that cytokines and immune cells mediate this response in a tissue-specific manner.