Catalpol decreases peroxynitrite formation and consequently exerts cardioprotective effects against ischemia/reperfusion insult

Context: Peroxynitrite (ONOO^?) formation triggers oxidative/nitrative stress and contributes to exacerbated myocardial ischemia/reperfusion (MI/R) injury. Catalpol, an iridoid glycoside, abundantly found in the roots of Rehmannia glutinosa L. that is included in the family Phrymaceae in the order Lamiales, endemic to China, was found to have neuroprotective effects. However, the effect of catalpol on MI/R injury has not been identified.

Objective: This study investigated whether catalpol attenuates oxidative/nitrative stress in acute MI/R.

Materials and methods: Adult male rats were subjected to 30?min of myocardial ischemia and 3?h of reperfusion and were treated with saline, catalpol (5?mg/kg, i.p., 5?min before reperfusion) or catalpol plus wortmannin (15 µg/kg intraperitoneally injected 15?min before reperfusion).

Results: Pretreatment with catalpol significantly improved cardiac functions, reduced myocardial infarction, apoptosis and necrosis of cardiomyocytes after MI/R (all p < 0.05). Meanwhile, ONOO^? formation was markedly reduced after catalpol treatment (3.01?±?0.22 vs. 4.66?±?0.53 pmol/mg protein in vehicle, p < 0.05). In addition, catalpol increased Akt and endothelial nitric oxide synthase phosphorylation, nitric oxide (NO) production, anti-oxidant capacity and reduced MI/R-induced inducible nitric oxide synthase expression and superoxide anion (·O₂^?) production in I/R hearts. PI3K inhibitor wortmannin not only blocked catalpol-induced Akt activation, but also attenuated all the beneficial effects of catalpol. Suppression of ONOO^? formation by either catalpol or an ONOO^? scavenger uric acid (5?mg/kg) reduced myocardial infarct size in MI/R rats.

Discussion and conclusion: In conclusion, catalpol affords cardioprotection against MI/R insult by attenuating ONOO^? formation, which is attributable to increased physiological NO and decreased ·O₂^? production.     

The opposite effects of nitric oxide donor,S‐nitrosoglutathione,on myocardial ischaemia/reperfusion injury in diabetic and non‐diabetic mice

Nitric oxide is a potent anti‐apoptotic and cardioprotective molecule in healthy animals. However, recent study demonstrates that overexpression of eNOS exacerbates the liver injury in diabetic animals. whether diabetes may also alter NO's biologic activity in ischaemic/reperfused heart remains unknown. The present experiment was designed to determine whether the nitric oxide donor, S‐nitrosoglutathione, may exert different effects on diabetic and non‐diabetic myocardial ischaemia/reperfusion (MI/R) injury. Diabetic state was induced in mice by multiple intraperitoneal injections of low‐dose streptozotocin (STZ). The control or diabetic mice were subjected to 30 minutes ischaemia and 3 or 24 hours reperfusion. At 10 minutes before reperfusion, diabetic and non‐diabetic mice were received an intraperitoneal injection of S‐nitrosoglutathione (GSNO, a nitric oxide donor, 1 μmol/kg). GSNO attenuated MI/R injury in non‐diabetic mice, as measured by improved cardiac function, reduced infarct size and decreased cardiomyocyte apoptosis. In contrast, GSNO failed to attenuate but, rather, aggravated the MI/R injury in diabetic mice. Mechanically, the diabetic heart exhibited an increased nitrative/oxidative stress level, as measured by peroxynitrite formation, compared with non‐diabetic mice. Co‐administration of GSNO with EUK134 (a peroxynitrite scavenger) or MnTE‐2‐PyP5 (a superoxide dismutase mimetic) or Apocynin (a NADPH oxidase inhibitor) 10 minutes before reperfusion significantly decreased the MI/R‐induced peroxynitrite formation and the MI/R injury. Collectively, the present study for the first time demonstrated that diabetes may cause superoxide overproduction, increase NO inactivation and peroxynitrite formation, and thus convert GSNO from a cardioprotective molecule to a cardiotoxic molecule.     

Alpha-lipoic acid protects against myocardial ischemia/reperfusion injury via multiple target effects

Myocardial ischemia/reperfusion (MI/R) is a major cause for the events of cardiovascular disease. Oxidative stress plays a critical role in the development of ischemia/reperfusion (IR) injury. As a potent antioxidant, alpha-lipoic acid (LA) has been shown to provide a benefit for the inhibition of IR injury and inhibit reactive oxygen species (ROS) generation during MI/R in rats. However, the mechanism on the protective effect of LA is still to be clarified. The present study was aimed to investigate the protective effect of LA against MI/R injury and its mechanisms. We found that 2 h of myocardial ischemia followed by different time periods of reperfusion resulted in significant increase of creatine kinase (CK) activity. MI/R also significantly promoted oxidative stress and decreased the activities of antioxidant enzymes. In addition, apoptosis and inflammatory response were activated and aggravated in a time-dependent manner by MI/R. All these alterations induced by MI/R were attenuated by the administration of LA 30 min before reperfusion. These results suggested that LA played a protective effect against MI/R injury via antioxidant, anti-apoptotic and anti-inflammatory effects. These findings may significantly better the understanding of the pharmacological actions of LA and advance therapeutic approaches to MI/R injury and cardiovascular diseases.     

一种抗心肌缺血/再灌注损伤的新化合物的合成及心肌保护作用研究

在心肌缺血/再灌注 (MI/R) 时, 一氧化氮 (NO) 生成量减少, 氧自由基 (ROS) 大量堆积, 均可加重MI/R损伤。据此设计合成了可同时释放NO的ROS清除剂——乙酰阿魏单硝酸异山梨醇酯 (AFI), 并研究了AFI对MI/R大鼠的心肌保护作用及其作用机制。建立常规大鼠MI/R (30 min/3 h) 模型, 随机给予AFI (10 mg·kg^-1)、阿魏酸 (40 mg·kg^-1) 或单硝酸异山梨酯 (30 mg·kg^-1) 药物治疗 (ig), 再灌注末检测大鼠心肌梗死面积和心功能指标, 同时测定血清肌酸激酶、乳酸脱氢酶、超氧化物歧化酶活性、过氧化氢与丙二醛水平及NO含量。与阿魏酸钠、单硝酸异山梨醇单独治疗组或联合治疗组相比, AFI治疗组心肌梗死面积显著减小 (n = 8, P < 0.01), 左室发展压、左室等容收缩/舒张期压力上升或下降最大速率显著提高 (n = 8, P < 0.05), 血清肌酸激酶和乳酸脱氢酶活性显著降低。与阿魏酸钠或单硝酸异山梨醇单独治疗组相比, AFI治疗组血清超氧化物歧化酶活性增加、过氧化氢与丙二醛含量降低而NO含量显著升高 (n = 8, P均< 0.05)。这些结果表明, AFI这一新化合物可减轻大鼠MI/R损伤, 具有保护心脏功能, 其心肌保护作用比阿魏酸钠、单硝酸异山梨醇的单独使用或联合使用均强。     

E-selectin in the pathogenesis of experimental myocardial ischemia-reperfusion injury

The role of E-selectin in the pathogenesis of an experimental model of myocardial ischemia-reperfusion injury was investigated. Pentobarbital anesthetized rats underwent left main coronary artery ligation (1 h) followed by reperfusion (1 h; MI/R). Sham operated rats were used as controls (sham MI/R). Myocardial ischemia-reperfusion injury reduced survival rate (50%), caused severe myocardial damage (necrotic area/area-at-risk 69.8 ± 5%; necrotic area/total=area = 56 ± 7.6%), increased serum creatine phosphokinase activity (sham MI/R = 33 ± 3 U/ml; MI/R = 215 ± 13 U/ml) and elevated myeloperoxidase activity (investigated as an index of leukocyte adhesion and accumulation; sham MI/R = 0.11 ± 0.02 U × 10⁻³/g tissue) in the area-at-risk (7.5 ± 1.7 U × 10⁻³/g tissue) and in the necrotic area (7.8 ± 2.2 U × 10⁻³/g tissue). Furthermore, MI/R rats had an increased pressure rate index, studied as a quantitative means for assessing myocardial oxygen demand. Administration of a hyperimmune serum containing antibodies against E-selectin significantly improved survival rate (80%), reduced myocardial injury (necrotic area/area-at-risk = 26.4 ± 7%, P < 0.005; necrotic area/total area 19.1 ± 2.8%, P < 0.005), lowered serum creatine phospokinase activity (85 ± 5 U/ml, P < 0.001) and decreased myeloperoxidase actibity in the area at risk (3.7 ± 1.3 U × 10⁻³/g tissue, P < 0.001) and in the necrotic area (3.0 ± 0.7 U × 10⁻³/g tissue). Finally, the administration of anti E-selection antibodies improved the PRI in MI/R rats. The present data suggest that E-selectin in vivo plays a key role in the pathogenesis of myocardial ischemia/reperfusion injury.     

Immunomodulation by splenectomy or by FTY720 protects the heart against ischemia reperfusion injury

The pathogenesis of myocardial ischemia‐reperfusion injury (MI/R) involves an inflammatory response in the myocardium undergoing reperfusion. Modulation of this response by splenectomy constitutes an option to protect the heart from MI/R. To mimic the effect of splenectomy in a pharmacological approach, the sphingosine‐1‐phosphate agonist FTY720 was applied at the onset of reperfusion. In a closed chest model of MI/R, infarct size was assessed by triphenyltetrazolium chloride staining after 1 h of ischemia and 24 h of reperfusion, and by Masson trichrome staining 21 days after reperfusion in splenectomised mice, mice post‐conditioned with FTY720 IP (1 mg/kg), and controls. In addition, hemodynamic parameters were recorded after 24 h and 21 days by catheterization. Infarct size, and immune cell invasion of phagocytic monocytes investigated by FACS after 24 h of reperfusion were significantly reduced by both splenectomy, and FTY720 treatment. Evaluation after 21 days of reperfusion revealed that FTY720 treated animals had an improved hemodynamic outcome compared to placebo treated as well as splenectomised animals. FTY720 treatment reduced cell injury as effectively as splenectomy by lowering the number of phagocytic monocytes invading the myocardium and ameliorated hemodynamic outcome within the first 21 days.     

Fenofibrate attenuates impaired ischemic preconditioning-mediated cardioprotection in the fructose-fed hypertriglyceridemic rat heart

We investigated in this study whether or not the ischemic preconditioning (IPC)-mediated cardioprotective effect against ischemia–reperfusion (I/R) injury exists in the fructose-fed hypertriglyceridemic (HTG) rat heart. Langendorff-perfused normal and fructose-fed (10 %?w/v in drinking water, 8 weeks) HTG rat hearts were subjected to 30-min global ischemia and 120-min reperfusion. IPC protocol included four brief episodes (5 min each) of ischemia and reperfusion. Myocardial infarct size using triphenyltetrazolium chloride staining, markers of cardiac injury such as lactate dehydrogenase (LDH) and creatine kinase (CK-MB) release, coronary flow rate (CFR), and myocardial oxidative stress were assessed. High degree of myocardial I/R injury, by means of significant myocardial infarct size, elevated coronary LDH and CK-MB release, reduced CFR, and high oxidative stress, was noted in the HTG rat heart as compared to the normal rat heart. The IPC-mediated cardioprotection against I/R injury was markedly impaired in the HTG rat heart as compared to the normal rat heart. Interestingly, pharmacological reduction of triglycerides using 8-week treatment protocol with fenofibrate (80 mg/kg/day, p.o.) restored the IPC effect in the HTG rat heart that was blunted by coinfusion, during the IPC reperfusion protocol, of a specific inhibitor of phosphoinositide-3-kinase (PI3-K), wortmannin (100 nM). The IPC failed to protect the HTG rat heart against I/R injury. Fenofibrate treatment reduced high triglycerides in the fructose-fed HTG rat and subsequently restored the cardioprotective effect of IPC.     

Thioredoxin reduces post-ischemic myocardial apoptosis by reducing oxidative/nitrative stress

BACKGROUND AND PURPOSE: Thioredoxin (Trx) is an oxidoreductase that prevents free radical-induced cell death in cultured cells. Here we assessed the mechanism(s) underlying the cardioprotective effects of Trx in vivo. EXPERIMENTAL APPROACH: The effects of myocardial ischemia (30 min) and reperfusion were measured in mice, with assays of myocardial apoptosis, superoxide production, NOx and nitrotyrosine content, and myocardial infarct size. Recombinant human Trx (rhTrx, 0.7-20 mg kg(-1), i.p.) was given 10 min before reperfusion. KEY RESULTS: Treatment with 2 mg kg(-1) rhTrx significantly decreased myocardial apoptosis and reduced infarct size (P<0.01). Nitrotyrosine content of cardiomyocytes was markedly reduced in rhTrx-treated animals (P<0.01). To further identify the mechanisms by which rhTrx may exert its anti-nitrative effect, iNOS expression and production of NOx and superoxide were determined. Treatment with rhTrx had no significant effect on iNOS expression or NOx content in the ischemic/reperfused heart. However, it markedly upregulated mSOD and reduced tissue superoxide content. To further establish a causative link between the anti- peroxynitrite effect and the cardioprotective effect of rhTrx, cultured adult cardiomyocytes were incubated with SIN-1, a peroxynitrite donor, (50 microM for 3 h) resulting in a nitrotyrosine content comparable to that seen in the ischemic/reperfused heart and causing significant cardiomyocyte apoptosis (P<0.01). Treatment with rhTrx markedly decreased SIN-1 induced apoptosis (P<0.01). CONCLUSIONS AND IMPLICATIONS: These results demonstrate that Trx is a novel anti-apoptotic and cardioprotective molecule that exerts its cardioprotective effects by reducing ischemia/reperfusion-induced oxidative/nitrative stress.     

Glutamine contributes to ameliorate inflammation after renal ischemia/reperfusion injury in rats

The aim of this study was to investigate the effects of glutamine in an in vivo rat model of renal ischemia/reperfusion (I/R) injury. Male Wistar rats underwent bilateral renal pedicle clamping for 45 min followed by reperfusion for 6 h. Glutamine (1.5 mg/kg) was administered intraperitoneally (i.p.) 15 min prior to reperfusion. Plasma concentrations of urea, creatinine, γ-glutamyl transferase (γ-GT), and aspartate aminotransferase (AST) were measured for the assessment of renal function and reperfusion injury. Markers of oxidative stress, expression of the pro-inflammatory mediators inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), AT-1 expression, and changes in the oxidative stress-sensitive nuclear factor kappa B (NF-κB) signaling pathway were measured to investigate whether glutamine can reduce the renal dysfunction. Kidney myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were measured for assessment of polymorphonuclear (PMN) cell infiltration and lipid peroxidation, respectively. Renal sections were used for histologic grading of renal injury and for immunohistochemical localization of nitrotyrosine and poly(ADP-ribose) synthetase (PARS). In vivo, glutamine significantly reduced the increase in urea, creatinine, γ-GT, AST, produced by renal ischemia/reperfusion (I/R), suggesting an improvement in both renal function and injury. Glutamine significantly reduced iNOS and NF-κB, kidney MPO activity and MDA levels, indicating a reduction in PMN infiltration and lipid peroxidation, respectively. Glutamine reduced the histological evidence of renal damage associated with I/R and caused a substantial reduction in the staining for nitrotyrosine and PARS, suggesting reduced nitrosative and oxidative stress. Moreover, glutamine attenuated the reduction of COX-2 expression and prevented the increased AT-1 expression after I/R. Our results suggest that glutamine reduces the renal dysfunction and injury associated with I/R of the kidney.     

Pretreatment with Tilianin improves mitochondrial energy metabolism and oxidative stress in rats with myocardial ischemia/reperfusion injury via AMPK/SIRT1/PGC-1 alpha signaling pathway

Mitochondrial energy metabolism and oxidative stress play a crucial role in ameliorating myocardial ischemia/reperfusion injury (MIRI). Tilianin has been reported to have a significant protection for mitochondrion in MIRI. However, the underlying mechanisms remain unknown. This study investigated whether Tilianin regulates mitochondrial energy metabolism and oxidative stress in MIRI via AMPK/SIRT1/PGC-1 alpha signaling pathway. The MIRI model was established by 30 min of coronary occlusion followed by 2 h of reperfusion in rats. The results revealed that Tilianin significantly reduced myocardial infarction, improved the pathological morphology of myocardium, markedly increased the contents of ATP and NAD⁺, decreased ADP and AMP contents and the ratio of AMP/ATP, reduced the level of ROS and MDA, enhanced SOD activity, evidently increased the levels of AMPK, SIRT1 and PGC-1 alpha mRNA, up-regulated the expressions of AMPK, pAMPK, SIRT1, PGC-1alpha, NRF1, TFAM and FOXO1 proteins. However, these effects were respectively abolished by Compound C (a specific AMPK inhibitor) and EX-527 (a specific SIRT1 inhibitor). Taken together, this study found that Tilianin could attenuate MIRI by improving mitochondrial energy metabolism and reducing oxidative stress via AMPK/SIRT1/PGC-1 alpha signaling pathway.     

A labdane diterpene exerts ex vivo and in vivo cardioprotection against post-ischemic injury: Involvement of AKT-dependent mechanisms

Therapeutic approaches to protect the heart from ischemia/reperfusion (I/R) injury are an area of intense research, as myocardial infarction is a major cause of mortality and morbidity. Diterpenes are bioactive natural products with great therapeutic potential. In the present study, we have investigated the in vivo cardioprotective effects of a labdane diterpene (DT1) against cardiac I/R injury and the molecular mechanisms involved. DT1 attenuates post-ischemic injury via an AKT-dependent activation of HIF-1α, survival pathways and inhibition of NF-κB signaling. Myocardial infarction (MI) was induced in Wistar rats occluding the left coronary artery (LCA) for 30 min followed by 72 h reperfusion. DT1 (5 mg/kg) was intravenously administered at reperfusion. In addition, we investigated the mechanisms of cardioprotection in the Langendorff-perfused model. Cardioprotection was observed when DT1 was administered after myocardial injury. The molecular mechanisms involved the activation of the survival pathway PDK-1, AKT and AMPK, a reduced phosphorylation of PKD1/2 and sustained HIF-1α activity, leading to increased expression of anti-apoptotic proteins and decreased caspase-3 activation. Pharmacological inhibition of AKT following MI and prior to DT1 challenge significantly decreased the cardioprotection afforded by DT1 therapy at reperfusion. Cardiac function after MI was significantly improved after DT1-treatment, as evidenced by hemodynamic recovery and decreased myocardial infarct size. These findings demonstrate an efficient in vivo cardioprotection by diterpene DT1 against I/R when administered at reperfusion, opening new therapeutic strategies as adjunctive therapy for the pharmacological management of I/R injury.     

天山花楸叶总黄酮对大鼠心肌缺血/再灌注损伤的保护作用

目的观察天山花楸叶总黄酮对大鼠心肌缺血/再灌注(I/R)损伤的保护作用,探讨其作用机制。方法采用改良的Langendorff逆行恒压灌流方法,建立大鼠离体心脏I/R损伤模型,观察天山花楸叶总黄酮(4.0、6.0mg·L-1)对心脏I/R损伤后心功能、心肌组织中超氧岐化酶(SOD)活性和丙二醛(MDA)含量变化的影响。利用DPPH、羟自由基、超氧阴离子、脂质过氧化反应体系,检测了天山花楸叶总黄酮(6.25、12.5、25、50、100mg·L-1)体外抗氧化能力。结果天山花楸叶总黄酮(6.0mg·L-1)可明显改善离体心脏I/R损伤后左心室发展压(LVDP)和左室压力升高或降低最大速率(±dp/dtmax),明显增加冠脉流量;天山花楸叶总黄酮(6.0mg·L-1)处理后I/R损伤心肌组织中SOD活性升高,MDA含量减少。天山花楸叶总黄酮(6.25～100mg.L-1)可浓度依赖性地清除DPPH自由基、羟自由基和超氧阴离子自由基,并抑制脂质过氧化反应。结论天山花楸叶总黄酮对心肌缺血/再灌注损伤具有明显保护作用,与其具有较强的抗氧化活性有关。     

Modulation of the oxidative stress and inflammatory response by PPAR-gamma agonists in the hippocampus of rats exposed to cerebral ischemia/reperfusion

Agonists of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) exert protective effects in several models of ischemia/reperfusion injury, but their role in stroke is less clear. The study investigates the effects of two PPAR-gamma agonists, rosiglitazone and pioglitazone, on oxidative stress and inflammatory response induced by ischemia/reperfusion in the rat hippocampus. Common carotid artery occlusion for 30 min followed by 1 h reperfusion resulted in a significant increase in the generation of reactive oxygen species, nitric oxide and the end products of lipid peroxidation as well as markedly reduced endogenous antioxidant glutathione levels and up-regulated superoxide dismutase activity. Western blot analysis showed that ischemia/reperfusion lead to an increase in cyclooxygenase-2 (COX-2) expression, as well activating p38 and p42/44 mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB). Pre-treatment with either rosiglitazone or pioglitazone significantly reduced oxidative stress, COX-2 protein expression and activation of MAPKs and NF-kappaB. Taken together, the results provide convincing evidence that PPAR-gamma agonists exert protective effects in a rat model of mild forebrain ischemia/reperfusion injury by inhibiting oxidative stress and excessive inflammatory response.     

Physiologically tolerable insulin reduces myocardial injury and improves cardiac functional recovery in myocardial ischemic/reperfused dogs

This study was designed to examine whether physiologically tolerable insulin, which maintains lower blood glucose, can protect the myocardium against ischemia/reperfusion (I/R) injury in a preclinical large animal model. Adult dogs were subjected to 50 minutes of myocardial ischemia (80% reduction in coronary blood flow) followed by 4 hours of reperfusion and treated with vehicle, glucose-insulin-potassium (GIK; glucose, 250 g/L; insulin, 60 U/L; potassium, 80 mmol/L), GK, or low-dose insulin (30 U/L) 10 minutes before reperfusion. Treatment with GIK exerted significant cardioprotective effects as evidenced by improved cardiac function, improved coronary blood flow, reduced infarct size, and myocardial apoptosis. In contrast, treatment with GK increased blood glucose level and aggravated myocardial I/R injury. It is interesting that treatment with insulin alone at the dose that reduced blood glucose to a clinically tolerable level exerted significant cardioprotective effects that were comparable to that seen in the GIK-treated group. This low-dose insulin had no effect on coronary blood flow after reperfusion but markedly reduced coronary reactive hyperemia and switched myocardial substrate uptake from fat to carbohydrate. Our results suggest that lower glucose supply to the ischemic myocardium at early reperfusion may create a "metabolic postconditioning" and thus reduce myocardial ischemia/reperfusion injury after prolonged reperfusion.     

Gasdermin D-mediated pyroptosis in myocardial ischemia and reperfusion injury: Cumulative evidence for future cardioprotective strategies

Cardiomyocyte death is one of the major mechanisms contributing to the development of myocardial infarction (MI) and myocardial ischemia/reperfusion (MI/R) injury. Due to the limited regenerative ability of cardiomyocytes, understanding the mechanisms of cardiomyocyte death is necessary. Pyroptosis, one of the regulated programmed cell death pathways, has recently been shown to play important roles in MI and MI/R injury. Pyroptosis is activated by damage-associated molecular patterns (DAMPs) that are released from damaged myocardial cells and activate the formation of an apoptosis-associated speck-like protein containing a CARD (ASC) interacting with NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), resulting in caspase-1 cleavage which promotes the activation of Gasdermin D (GSDMD). This pathway is known as the canonical pathway. GSDMD has also been shown to be activated in a non-canonical pathway during MI and MI/R injury via caspase-4/5/11. Suppression of GSDMD has been shown to provide cardioprotection against MI and MI/R injury. Although the effects of MI or MI/R injury on pyroptosis have previously been discussed, knowledge concerning the roles of GSDMD in these settings remains limited. In this review, the evidence from in vitro, in vivo, and clinical studies focusing on cardiac GSDMD activation during MI and MI/R injury is comprehensively summarized and discussed. Implications from this review will help pave the way for a new therapeutic target in ischemic heart disease.     

白介素8和兔心肌缺血/再灌注损伤研究

目的 探讨白介素8(rhIL-8)参与兔心肌缺血/再灌注损伤的机制,为减轻再灌注损伤探索新的治疗途径。方法 结扎兔冠状动脉左前降支(left anterior descending coronary artery,LAD)造成缺血1小时,再灌注3.5小时。实验分两组:缺血/再灌注组(MI/R,n=8)和假结扎组(Sham MI/R,n=8)。结果 MI/R组发生严重的心肌损伤,包括受累心肌髓过氧化物酶(myeloperoxidase,MPO)活性增大和血清肌酸磷酸激酶-MB同工酶(CPK-MB)、异构前列腺素(eoi-PGF_(2α))水平增高(均P<0.01)。血清IL-8浓度逐渐升高,免疫组化示受损心肌区血管内皮基底膜呈IL-8阳性染色。结论 血管内皮细胞释放的IL-8是吸引中性粒细胞浸润于缺血区心肌,造成缺血/再灌注损伤的因素之一。     

丹酚酸B镁对兔急性心梗再灌注后无复流心肌损伤的保护作用

目的 评价丹酚酸B镁（salvianolic acid B,Sal-B）对兔急性心肌梗死再灌注后心肌损伤的保护作用。方法 新西兰大白兔40只随机分成4组,即假手术组、心肌缺血再灌注（myocardial ischemia/reperfusion,MI/R）、再灌注低剂量组（Sal-B20 mg·kg^-1组）、再灌注高剂量组（Sal-B 60 mg·kg^-1组）,每组10只。假手术组只开胸不结扎,其余3组结扎左室缘支90 min,切断结扎线120 min,建立MI/R模型。各组分别于结扎左心室缘支前5 min、结扎后90 min、再灌注120 min时取血,检测肌酸激酶同工酶（CK-MB）、心肌肌钙蛋白I （cTnI）,并评估缺血范围、无复流范围及梗死区心肌范围。结果 结扎90 min后,MI/R组、Sal-B 20 mg·kg^-1组和Sal-B 60 mg·kg^-1组3组之间CK-MB、cTnI水平差异无统计学意义。再灌注120 min后,Sal-B 60 mg·kg^-1组的血清CK-MB、cTnI水平显著低于MI/R组、Sal-B 20 mg·kg^-1组,差异有统计学意义（P<0.05）。各组染色所测的冠脉结扎区心肌缺血范围基本一致。与MI/R组、Sal-B 20 mg·kg^-1组比,Sal-B 60 mg·kg^-1组可以显著减少无复流面积（P<0.05）和梗死面积（P<0.05）,MI/R组和Sal-B 20 mg·kg^-1组之间差异无统计学意义。结论 Sal-B 60 mg·kg^-1能在一定程度上减轻心肌细胞结构损伤,缩小心肌梗死面积,减轻无复流的发生。     

Exendin-4 protects the hearts of rats from ischaemia/reperfusion injury by boosting antioxidant levels and inhibition of JNK/p66Shc/NADPH axis

Exendin-4, a glucagon-like peptide-1 receptor agonist, was shown to protect against cardiac ischaemia/reperfusion (I/R) injury by suppressing oxidative stress. p⁶⁶Shc, a pro-oxidant and an apoptotic protein, is activated in the infarcted left ventricles (LVs) after induction of I/R. This study investigated if the cardiac protective effect of Exendin-4 against I/R injury in rats involves inhibition of p⁶⁶Shc and to determine the underlying mechanisms behind this. Adult male rats (n = 12/group) were divided into four groups as a sham, a sham + Exendin-4, an I/R, and an I/R + Exendin-4. Exendin-4 was administered to rats 7 days before the induction of I/R. Ischaemia was induced by ligating the left anterior descending (LAD) coronary artery for 40 minutes followed by reperfusion for 10 minutes. The infarct myocardium was used for further analysis. Exendin-4 significantly reduced infarct area (by 62%), preserved LV function and lowered serum levels of LDH and CK-MB in I/R-induced rats. Also, it significantly reduced LV levels of ROS and MDA and protein levels of cytochrome-c and cleaved caspase-3 but significantly increased levels of glutathione (GSH) and manganese superoxide dismutase (MnSOD) in LVs of I/R rats indicating antioxidant and anti-apoptotic effects. Furthermore, it inhibited JNK and p⁶⁶Shc activation and downregulated protein levels of p⁶⁶Shc and NADPH oxidase with no effect on protein levels/activity of p53 and PKCβII. Of note, Exendin-4 also increased GSH and MnSOD in LVs of control rats. In conclusion, Exendin-4 cardioprotective effect in I/R hearts is mediated mainly by antioxidant effect and inhibition of JNK/P⁶⁶Shc/NADPH oxidase.     

Cardiac protection of Bauhinia championii against reperfusion injury

This study aims to investigate the protective effects of the Bauhinia championii (BC) against ischemia/reperfusion (I/R)‐induced injury in an isolated heart model. Langendorff‐perfused C57BL/6JNarl mice hearts were performed with 30 minutes ischemia and 60 minutes reperfusion by left anterior descending artery ligation. Before reperfusion, boiling water extracts of BC (10 mg/L) was pretreated for 15 minutes. During reperfusion, BC significantly decreased the occurrence of ventricular arrhythmias by lead II electrocardiogram (ECG). Electrophysiological effect of BC was further determined in isolated ventricular myocytes by whole‐cell patch clamp technique. The underlying mechanism may result from its Na⁺ channel blocking activity characterized with reduced rise slope of action potential and Na⁺ current density. Moreover, BC dramatically reduced I/R‐caused infarct size, which was accessed by 2,3,5‐triphenyltetrazolium chloride (TTC) assay. Since BC decreased I/R‐induced myoglobin release and oxidation of Ca²⁺‐calmodulin‐dependent protein kinase, inhibition of myocardial necroptosis may account for the protective effects of BC on myocytes lose. This study indicated that BC may prevent I/R induced ventricular arrhythmias and myocyte death by blocking Na⁺ channels and decreasing necroptosis, respectively. Since most of the available antiarrhythmic remedies have unwanted adverse actions, BC could be a novel candidate for the treatment of myocardial infarction and ventricular arrhythmia.     

无创性延迟肢体缺血预适应对糖尿病大鼠心肌缺血/再灌注氧化损伤的影响

目的:观察无创性延迟肢体缺血预适应(NDLIP)对糖尿病(DM)大鼠心肌缺血/再灌注氧化损伤的保护作用。方法:尾静脉注射链脲佐菌素(STZ)制备DM大鼠模型。将DM大鼠随机分成心肌缺血再灌注(I/R)、心肌缺血预适应(MIP)、无创性延迟肢体缺血预适应(NDLIP)组。通过3个循环的左后肢5 min缺血/5 min再灌注,每天1次,连续3 d,建立NDLIP模型。心肌冠状动脉左前降支(LAD)实施3次5 min缺血/5 min再灌注建立MIP模型。各组实施LAD 30 min缺血/120 min再灌注复制I/R模型。用BL-420E生物机能实验系统连续监测心电图(ECG),记录缺血期间室性心律失常(VA)的发生情况。TTC染色测定大鼠心肌I/R后梗死面积(IS)。检测心肌组织中总-超氧化物歧化酶(T-SOD)、锰-超氧化物歧化酶(Mn-SOD)活性及丙二醛(MDA)含量。结果:与I/R组相比,MIP组和NDLIP组室性早搏(VPC)出现时间明显推迟(P<0.01),持续时间明显缩短(P<0.01),室性心动过速(VT)和心室纤颤(VF)发生率都明显降低(P<0.05),IS明显缩小,梗死面积/危险区(IS/A...