Simvastatin attenuates renal ischemia/reperfusion injury in rats administered cyclosporine A

BACKGROUND: 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors increase renal blood flow independent of their lipid-lowering properties. In organ transplantation, the calcineurin inhibitor cyclosporine A (CyA) is the immunosuppressant of choice. However, its renal vasoconstrictor properties limit its use. This study aimed to determine the effect of an HMG-CoA reductase inhibitor, simvastatin (Zocor), on renal function in rats after ischemia/reperfusion injury (I/R) with concomitant CyA treatment. METHODS: Male Wistar rats (250 g) were anesthetized and the suprarenal aorta clamped for 40 minutes. The right kidney was removed. After recovery, the rats were divided into 5 groups: (1) control rats, no ischemia, no treatment; (2) ischemia with no treatment; (3) ischemia plus CyA only; (4) ischemia plus CyA and low-dose simvastatin; and (5) ischemia plus CyA and high-dose simvastatin. Five to 7 days after I/R injury, glomerular filtration rate (GFR) was determined using urinary iohexol clearance. RESULTS: The GFR values (mL/min) for all 5 groups were as follows: (1) 1.23 +/- 0.08; (2) 1.05 +/- 0.10; (3) 0.44 +/- 0.06 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); (4) 0.51 +/- 0.04 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); and (5) 0.85 +/- 0.11. CONCLUSIONS: After I/R injury and cyclosporine treatment, simvastatin preserved renal function compared with cyclosporine treatment alone because it may not have a direct vasoconstrictor effect on the renal microcirculation. In fact, it may exhibit vasodilator properties on the renal microcirculation mediated by nitric oxide.     

心脏死亡器官捐献供肾的缺血再灌注损伤

接受心脏死亡器官捐献(DCD)供肾受者移植肾功能延迟恢复(DGF)发生率明显高于传统尸体供肾,其根本原因是DCD供肾缺血再灌注损伤(IRI).最近研究发现DCD供者体内补体C3a和C5a活化与供肾IRI密切相关,该研究将完善对C3a和C5a活化在DCD供肾IRI中作用机制的认识,并为DCD供肾IRI的防治寻找新的靶点.     

Gentamicin effects on renal ischemia/reperfusion injury.

This study assessed gentamicin's effects on ischemia/reperfusion renal injury to better understand when and how it worsens postischemic acute renal failure. Rats were subjected to 25 minutes of renal pedicle occlusion with and without preischemic (15-minute) or postischemic (15-minute or 8-hour) gentamicin treatment (100 mg/kg, by itself a subtoxic dose). Gentamicin's impact on hypoxia/reoxygenation injury to isolated rat proximal tubular segments was also assessed. Preischemic and postischemic gentamicin worsened the severity of acute renal failure to the same degree, suggesting that pretreatment induces its effect in the reperfusion period. Gentamicin paradoxically lessened hypoxic damage to proximal tubular segments (assessed by lactate dehydrogenase release), again implying no adverse impact on oxygen deprivation-induced tubular injury. From 0-4 hours of reperfusion, gentamicin approximately halved ATP/ADP ratios (due to increased ADP), indicating a drug-induced defect in cellular energetics. This abnormality temporally correlated with evolving morphological damage. Although antioxidants (deferoxamine and sodium benzoate) have been reported to protect against pure aminoglycoside nephrotoxicity, they did not mitigate gentamicin's adverse impact on postischemic acute renal failure. Gentamicin did not influence ischemia/immediate reperfusion deacylation/reacylation (assessed by renal free fatty acid content) despite its known antiphospholipase activity. Although in the normal kidney gentamicin preferentially accumulated in cortex, in the postischemic kidney, both cortex and outer medullary stripe developed striking (approximately threefold to fivefold) and comparable gentamicin increments. In conclusion, gentamicin appears to exacerbate postischemic acute renal failure by adversely influencing the reperfusion, not the ischemic injury, process. This may occur because increased gentamicin accumulation negatively impacts on reperfusion cellular energetics.     

The role of L-arginine in ameliorating reperfusion injury after myocardial ischemia in the cat.

BACKGROUND. Myocardial ischemia followed by reperfusion results in endothelial dysfunction characterized by a reduced release of endothelium-derived relaxing factor (EDRF). Because EDRF has been characterized as nitric oxide, we examined the ability of L-arginine, the substrate for nitric oxide synthesis, to protect in a feline model of myocardial ischemia plus reperfusion. METHODS AND RESULTS. The effects of L-arginine were investigated in a 6-hour model of myocardial ischemia and reperfusion in pentobarbital-anesthetized cats. A bolus administration (30 mg/kg) of L-arginine, or its enantiomer D-arginine, was given followed by a continuous infusion of 10 mg/kg/min for 1 hour starting 10 minutes before reperfusion. Myocardial ischemia plus reperfusion in cats receiving D-arginine resulted in severe myocardial injury and endothelial dysfunction characterized by marked myocardial necrosis, high cardiac myeloperoxidase activity in ischemic cardiac tissue, and loss of acetylcholine- and A-23187-induced endothelium-dependent relaxation in coronary artery rings. In contrast, myocardial ischemia plus reperfusion cats treated with L-arginine exhibited a reduced area of cardiac necrosis (16 +/- 2% versus 41 +/- 5% of area at risk, p less than 0.01), lower myeloperoxidase activity in the ischemic region (0.3 +/- 0.08 versus 0.8 +/- 0.10 units/100 mg tissue, p less than 0.05), and significant preservation of acetylcholine- (p less than 0.01) and A-23187- (p less than 0.01) induced endothelial-dependent relaxation. CONCLUSIONS. These results demonstrate the ability of L-arginine to reduce necrotic injury in a cat model of myocardial ischemia plus reperfusion, and this reduction in infarct size is associated with the preservation of endothelial function and attenuation of neutrophil accumulation in ischemic cardiac tissue.     

Recombinant angiopoietin-like protein 4 attenuates intestinal barrier structure and function injury after ischemia/reperfusion

BACKGROUNDIntestinal barrier breakdown, a frequent complication of intestinal ischemia-reperfusion (I/R) including dysfunction and the structure changes of the intestine, is characterized by a loss of tight junction and enhanced permeability of the intestinal barrier and increased mortality. To develop effective and novel therapeutics is important for the improvement of outcome of patients with intestinal barrier deterioration. Recombinant human angiopoietin-like protein 4 (rhANGPTL4) is reported to protect the blood-brain barrier when administered exogenously, and endogenous ANGPTL4 deficiency deteriorates radiation-induced intestinal injury. AIMTo identify whether rhANGPTL4 may protect intestinal barrier breakdown induced by I/R.METHODSIntestinal I/R injury was elicited through clamping the superior mesenteric artery for 60 min followed by 240 min reperfusion. Intestinal epithelial (Caco-2) cells and human umbilical vein endothelial cells were challenged by hypoxia/ reoxygenation to mimic I/R in vitro.RESULTSIndicators including fluorescein isothiocyanate-conjugated dextran (4 kilodaltons; FD-4) clearance, ratio of phosphorylated myosin light chain/total myosin light chain, myosin light chain kinase and loss of zonula occludens-1, claudin-2 and VE-cadherin were significantly increased after intestinal I/R or cell hypoxia/reoxygenation. rhANGPTL4 treatment significantly reversed these indicators, which were associated with inhibiting the inflammatory and oxidative cascade, excessive activation of cellular autophagy and apoptosis and improvement of survival rate. Similar results were observed in vitro when cells were challenged by hypoxia/reoxygenation, whereas rhANGPTL4 reversed the indicators close to normal level in Caco-2 cells and human umbilical vein endothelial cells significantly.CONCLUSIONrhANGPTL4 can function as a protective agent against intestinal injury induced by intestinal I/R and improve survival via maintenance of intestinal barrier structure and functions.     

促红细胞生成素与心肌缺血再灌注损伤

近年来促红细胞生成素(erythropoietin,EPO)的非造血生物作用逐渐引起关注。研究表明,EPO 可以减轻缺血缺氧时心肌细胞的损伤,减少心肌细胞的调亡,从而使其可能成为预防和治疗心肌缺血再灌注损伤的一条途径。     

大鼠急性缺血性肾衰竭不同时段肾功能变化

目的观察大鼠肾脏缺血/再灌注损伤（IRI）模型不同时段肾功能、肾脏/体重指数变化情况。方法建立大鼠肾脏IRI模型,监测大鼠术后不同时段血清尿素氮（BUN）、肌酐（SCr）、血钾及肾脏/体重指数,了解IRI大鼠肾功能变化情况。结果 （1）术后12 h肾脏/体重指数显著升高,至手术后48 h达高峰,于手术后72 h开始回落。（2）术后6 h血清BUN、SCr、血钾显著升高,至术后48 h达高峰,从术后72 h开始回落。结论 IRI大鼠模型手术后肾脏/体重指数、血清BUN、SCr、血钾均有不同程度的升高,高峰期均在术后48 h,提示肾功能损害最严重是在手术后48 h。     

miR-17-92 ameliorates renal ischemia reperfusion injury

There is limited information on the role of miR-17-92 in renal tubular pathophysiology. Therefore, the present study was performed to determine whether miR-17-92 plays a role in ischemia-reperfusion injury (IRI)-induced acute kidney injury. We originally demonstrated that miR-17-92 is up-regulated following IRI in vivo. To explore the roles of miR-17-92 in the IRI process, we first generated a renal proximal tubule-specific miR-17-92 deletion (PT-miR-17-92^?/?) knockout mouse model with Cre driven by the Kap promoter. We found that PT-deficient miR-17-92 mice had more severe renal dysfunction and renal structures than their littermates. Compared with sham-operated mice, both wide-type (WT) mice and PT-miR-17-92^?/? mice showed increased serum levels of creatinine and urea. However, the levels of serum urea and creatinine in PT-miR-17-92^?/? mice after the IRI operation were significantly higher than the levels in WT mice. In addition, PT-miR-17-92^?/? mice showed higher levels of serum potassium and phosphonium after the IRI operation. Histological analysis revealed that PT-miR-17-92^?/? mice had substantial histopathologic changes, such as tubular dilation and tubular necrosis. Overexpression of miR-17-92 could partially reverse the side-effects of IRI on the proximal tubules in vivo. Furthermore, we employed a quantitative proteomic strategy and identified 16 proteins as potential targets of miR-17-92. Taken together, our findings suggested that miR-17-92 may ameliorates IRI-induced acute kidney injury. Our results indicate that pharmacologic modulation of these miRNAs may have therapeutic potential for acute kidney injury.     

血管活性物质对肾缺血再灌注损伤的影响

肾缺血再灌注损伤是导致急性肾小管坏死和肾移植失败的重要因素,如何减轻和预防肾脏缺血再灌注损伤,一直是保护急性肾损伤研究的主要内容.肾缺血再灌注损伤的发病机制非常复杂,研究资料表明,内皮素1、一氧化氮和肾素-血管紧张素系统(RAS)中的主要活性物质如血管紧张素Ⅱ和血管紧张素(1-7)等血管活性物质可能在肾缺血再灌注损伤中起重要作用,并参与其发生、发展.     

宝霍甙元对大鼠急性肾缺血-再灌注损伤的保护作用

目的:观察宝藿甙元在大鼠急性肾缺血-再灌注损伤中的保护作用。方法:采用在体左肾动脉钳夹暂时阻断肾血流法制备大鼠肾缺血-再灌注模型。将SD大鼠分为假手术组、溶剂组、药物组,术后饲养2周。在术后第3天每组取3只大鼠肾脏行病理检查,并在术后3、7、14d检测血清尿素氮(BUN)、肌酐(Cr)及24hCr清除率(CrCI)。结果:与溶剂组相比,术后3d药物组BUN及Cr降低。治疗1周后药物组BUN、Cr及CrCI等指标均改善,且达到与假手术组相近的水平。溶剂组各项指标均要在14d后才恢复到假手术组水平。结论:宝藿甙元可以减轻肾缺血-再灌注后的肾损伤,保护肾功能。     

Effect of N—desulfated heparin on hepatic／renal ischemia reperfusion injury in rats

AIM：To invesigate the effect of N-desulfated heparin on hepatic/renal ischemia and reperfusion injury in rats.METHODS:Using rat models of 60minutes hepatic of renal ischemia followed by 1h,3h,6hand24h reperfusion.animals were randomly divided into following groups,the sham operated controls,ischemic group receiving only normal saline,and treated group receiving N-desulfated heparin at a dose of 12mg/kg at 5minutes before reperfusion.P-selectin expression was detected in hepatic/renal tissues with immunohistochemistry method.RESULTS:P-selectin expression,serumALT,AST,BUNand Cr levels were significantly increased during60minute ischemia and 1h,3h,6hand24hreperfusion.while the increment was significantly inhibited,and hepatic/renal pathology observed by light microscopy was remarkably improved by treatment with the N-desulfated heparin.Furthermore.the heparin was found no effects on PT and KPTT.CONCLUSION:P-selectin might mediate neutrophil infitration and contribute to hepatic/renai ischemia and reperfusion.THe N-desulfated heparin might prevent hepatic/renal admage induced by ischemia and reperfusion injury without significant anticoagulant activity.     

心肌缺血再灌注损伤研究进展

急性心肌梗死是主要的致死致残原因,再灌注治疗是其标准的治疗方案,然而再灌注治疗伴随着再灌注损伤,再灌注损伤的机理目前还未完全清楚,分子、细胞、组织上的改变均与参与再灌注损伤,本文就心肌缺血再灌注损伤的研究进展作一综述。     

Nitrite mediates cytoprotection after ischemia/reperfusion by modulating mitochondrial function

Nitrite, once thought to be an inert biomarker of NO formation, is now recognized as an endocrine storage pool of bioactive NO. While nitrite mediates a number of hypoxic responses, one of its most robust effects is its ability to confer cytoprotection after ischemia/reperfusion in a number of organs and models. The mechanism of this cytoprotection appears to be mediated at the level of the mitochondrion. Here we review the studies demonstrating that nitrite is cytoprotective in the heart and describe the mechanism of this cytoprotection, which involves the post-translational modification of complex I leading to the modulation of mitochondrial reactive oxygen species generation at reperfusion. The mechanism of nitrite-dependent cytoprotection will be compared to other cytoprotective agents including NO and ischemic preconditioning.     

Allopurinol improves scavenging ability of the liver after ischemia/reperfusion injury

Abstract: Deterioration of energy metabolism and oxidative stress represent fundamental mechanisms in ischemia and reperfusion injury. In a normothermic ischemia/reperfusion rat model, we investigated whether allopurinol (ALL) may improve the scavenging ability of the liver after ischemia. ALL was given prior to ischemia and reperfusion (concentration 100 or 50 mg/kg) and controls were given a placebo. After a basal period of 30 min, 1 h normothermic ischemia was induced in the median and left liver lobes followed by 24 h observation. The overall liver function was assessed by bile secretion, and free oxygen production was assessed by glutathione efflux into bile during the first 60 min of reperfusion and at 24 h. Allopurinol (concentration 100 mg/kg) protected hepatocyte function as bile flow improved significantly in this group after 1 and 24 h of reperfusion compared with that of controls. Oxidative stress was also significantly attenuated in this group, as efflux of glutathione into bile was significantly higher in the ALL group (100 mg/kg) after 24 h but not after 1 h of reperfusion compared with that of controls. ALL given in a concentration 50 mg/kg had some, but a non-significant, effect. We conclude that biliary glutathione is an important marker of oxidative stress and may reflect the scavenging ability of the liver after ischemic injury. Significant correlation of bile flow with biliary glutathione during reperfusion indicates that oxidative stress is an important mechanism attenuating liver function after ischemia/reperfusion injury.     

Effect of tetramethylpyrazine on P-selectin and hepatic／rena ischemia and reperfusion injury in rats

AIM: To investigate the effect of tetramethylpyrazine on hepatic/renal ischemia and reperfusion injury in rats. METHODS: Hepatic/renal function, histopathological changes, and hepatic/renal P-selectin expression were studied with biochemical measurement and immunohistochemistry in hepatic/renal ischemia and reperfusion injury in rat models. RESULTS: Hepatic/renal insufficiency and histopathological damage were much less in the tetramethylpyrazine-treated group than those in the saline-treated groups. Hepatic/renal P-selectin expression was down regulated in the tetramethylpyrazine-treated group. CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion injury. Tetramethylpyrazine might prevent hepatic/renal damage induced by ischemia and reperfusion injury through inhibition of P-selectin.     

肾脏缺血再灌注损伤E-钙粘附素的表达研究

目的探讨肾脏缺血再灌注损伤时E-钙粘附素(E-cadherin)的变化。方法2006年1月至6月对解放军肾脏病研究所暨肾病重点实验室利用ATP耗竭剂抗霉素A建立的犬集合管上皮细胞(MDCK)缺血模型进行体外实验;体内实验使用双侧肾动脉钳闭法建立大鼠缺血再灌注损伤模型。PAS染色了解肾脏病理改变;E-cadherin免疫组化了解E-cadherin的定位和表达;Western bolt检测E-cadherin的蛋白表达。结果正常MDCK细胞E-cadherin在细胞膜表达,ATP耗竭4hE-cadherin表达极性消失,主要在细胞质表达。肾组织免疫组化显示,假手术组E-cadherin主要表达在肾小管上皮细胞基底膜侧;缺血肾脏组E-cadherin的表达极性消失,空泡变性的肾小管上皮细胞基底膜侧E-cadherin表达明显减少,主要在细胞质表达;而在脱落的肾小管上皮细胞只表达于细胞质。肾组织Western bolt显示,假手术组E-cadherin为120ku条带,缺血45min120ku条带减弱,出现明显的80ku条带,缺血60min120ku条带几乎检测不出,而主要表现为80ku条带。结论体内体外实验均证实,肾脏缺血再灌注损伤时E-cadherin的定位、蛋白表达量发生明显变化,并出现时间依赖性E-cadherin降解,使上皮细胞的极性和细胞间连接受损,部分解释了肾脏缺血再灌注损伤时上皮细胞脱落的原因。