肢体缺血预处理减轻大鼠海马缺血/再灌注损伤

目的:探讨肢体缺血预处理(LIP)对大鼠全脑缺血/再灌注损伤的影响.方法: 36只大鼠椎动脉凝闭后随机分为假手术(Control)组、脑缺血组、肢体缺血组、LIP 0 d组(LIP后即刻行脑缺血)、LIP 1 d组(LIP后1 d行脑缺血)和LIP 2 d组(LIP后2 d行脑缺血).重复夹闭大鼠双侧股动脉3次(每次10 min,间隔10 min)作为LIP,夹闭颈总动脉进行全脑缺血8 min后再灌注.硫堇染色观察海马CA1区组织学分级及锥体神经元密度以判断海马损伤程度.结果:脑缺血组海马CA1区锥体神经元损伤严重,与Control组比较,组织学分级明显升高,神经元密度明显降低(P<0.01).LIP 0 d组海马CA1区神经元损伤较脑缺血组明显减轻,组织学分级明显降低,神经元密度明显升高(P<0.01).而LIP 1 d组和LIP 2 d组大鼠海马CA1区锥体细胞缺失较多,仍有明显的组织损伤.结论:LIP可减轻随后立即发生的脑缺血/再灌注损伤,但对间隔1 d后的脑缺血/再灌注损伤无显著对抗作用.     

Fibroblast growth factors in myocardial ischemia / reperfusion injury and ischemic preconditioning

Angiogenic growth factors such as fibroblast growth factors (FGFs) are currently in clinical trials for accelerating blood vessel formation in myocardial and limb ischemic conditions. However, recent experimental evidence suggests that FGFs can also participate as endogenous cardioprotective agents. In this report, the current knowledge for FGFs implication in myocardial ischemic tolerance will be summarized. Pharmacologic preconditioning with drugs as FGFs that mimic the beneficial effects of ischemic preconditioning could lead to novel therapeutic approaches for the treatment of ischemic disorders including myocardial infarction and stroke.     

Inhibition of myocardial injury by ischemic postconditioning during reperfusion: comparison with ischemic preconditioning

Ischemic preconditioning (Pre-con) is an adaptive response triggered by a brief ischemia applied before a prolonged coronary occlusion. We tested the hypothesis that repetitive ischemia applied during early reperfusion, i.e., postconditioning (Post-con), is cardio-protective by attenuating reperfusion injury. In anesthetized open-chest dogs, the left anterior descending artery (LAD) was occluded for 60 min and reperfused for 3 h. In controls (n = 10), there was no intervention. In Pre-con (n = 9), the LAD was occluded for 5 min and reperfused for 10 min before the prolonged occlusion. In Post-con (n = 10), at the start of reperfusion, three cycles of 30-s reperfusion and 30-s LAD reocclusion preceded the 3 h of reperfusion. Infarct size was significantly less in the Pre-con (15 +/- 2%, P < 0.05) and Post-con (14 +/- 2%, P < 0.05) groups compared with controls (25 +/- 3%). Tissue edema (% water content) in the area at risk was comparably reduced in Pre-con (78.3 +/- 1.2, P < 0.05) and Post-con (79.7 +/- 0.6, P < 0.05) versus controls (81.5 +/- 0.4). Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase activity, Deltaabsorbance.min-1.g tissue-1) in the area at risk myocardium was comparably reduced in Post-con (10.8 +/- 5.5, P < 0.05) and Pre-con (13.4 +/- 3.4, P < 0.05) versus controls (47.4 +/- 15.3). Basal endothelial function measured by PMN adherence to postischemic LAD endothelium (PMNs/mm2) was comparably attenuated by Post-con and Pre-con (15 +/- 0.6 and 12 +/- 0.6, P < 0.05) versus controls (37 +/- 1.5), consistent with reduced expression of P-selectin on coronary vascular endothelium in Post-con and Pre-con. Endothelial function assessed by the maximal vasodilator response of postischemic LAD to acetylcholine was significantly greater in Post-con (104 +/- 6%, P < 0.05) and Pre-con (109 +/- 5%, P < 0.05) versus controls (71 +/- 8%). Plasma malondialdehyde (microM/ml), a product of lipid peroxidation, was significantly less at 1 h of reperfusion in Post-con (2.2 +/- 0.2, P < 0.05) versus controls (3.2 +/- 0.3) associated with a decrease in superoxide levels revealed by dihydroethidium staining in the myocardial area at risk. These data suggest that Post-con is as effective as Pre-con in reducing infarct size and preserving endothelial function. Post-con may be clinically applicable in coronary interventions, coronary artery bypass surgery, organ transplantation, and peripheral revascularization where reperfusion injury is expressed.     

Effect of ischemic preconditioning on free radical centers of the isolated rat heart during ischemia and early reperfusion

The effect of ischemic preconditioning on the free-radical state of isolated rat myocardium fixed by rapid freezing at the 25th min of normothermic total ischemia and the 3rd min of reperfusion was studied by the EPR method. It was shown that EPR spectra registered at -40 degrees C consist of two free-radical signals: of the semireduced forms of ubiquinone and flavine coynzymes. It was found that during ischemia and at the beginning of reperfusion, the preconditioning results in a narrowing of the spectra (as compared with control) due to an increase in the narrow ubisemiquinone EPR signal portion, and a decrease in the total concentration of free-radical centers: by 16% in the case of ischemia, and 23% in the case of reperfusion. It was concluded that in both cases the changes were due to a decrease in the concentration of myocardial flavosemiquinones as a result of ischemic preconditioning. We registered the microvawe power saturation curves for these two stages, which corresponded to control and ischemic preconditioning. In the case of ischemia these dependences had similar shapes; however, in the case of reperfusion they differ from each other due to changes in the relative intensities of the EPR signals from ubisemiquinone and flavosemiquinones in the integral myocardial free-radical spectra.     

Cardiac interstitial bradykinin release during ischemia is enhanced by ischemic preconditioning

Ischemic preconditioning is known to protect the myocardium from ischemia-reperfusion injury. We examined the transmural release of bradykinin during myocardial ischemia and the influence of ischemic preconditioning on bradykinin release during subsequent myocardial ischemia. Myocardial ischemia was induced by occlusion of the left anterior descending coronary artery in anesthetized cats. Cardiac microdialysis was performed by implantation and perfusion of dialysis probes in the epicardium and endocardium. In eight animals, bradykinin release was greater in the endocardium than in the epicardium (14.4 +/- 2.8 vs. 7.3 +/- 1.7 ng/ml, P < 0.05) during 30 min of ischemia. In seven animals subjected to preconditioning, myocardial bradykinin release was potentiated significantly from 2.4 +/- 0.6 ng/ml during the control period to 23.1 +/- 2.5 ng/ml during 30 min of myocardial ischemia compared with the non-preconditioning group (from 2.7 +/- 0.6 to 13.4 +/- 1.9 ng/ml, P < 0.05, n = 6). Thus this study provides further evidence that transmural gradients of bradykinin are produced during ischemia. The results also suggest that ischemic preconditioning enhances bradykinin release in the myocardial interstitial fluid during subsequent ischemia, which is likely one of the mechanisms of cardioprotection of ischemic preconditioning.     

Synergistic protective effect of ischemic preconditioning and allopurinol on ischemia/reperfusion injury in rat liver

This study examined the effects of ischemic preconditioning (IPC), allopurinol (Allo) or a combination of both on the extent of mitochondrial injury caused by hepatic ischemia/reperfusion (I/R). I/R increased the serum aminotransferase activity and the level of mitochondrial lipid peroxidation, whereas it decreased the mitochondrial glutathione level. Either IPC or Allo alone attenuated these changes with Allo+IPC having a synergistic effect. Allo increased the serum nitrite and nitrate level after brief ischemia. The significant peroxide production observed after 10 min of reperfusion after sustained ischemia was markedly attenuated by Allo+IPC. The mitochondria isolated after I/R were swollen, which was reduced by Allo+IPC. At the end of ischemia, the hepatic ATP level was lower and there was significant xanthine accumulation, which was attenuated by Allo+IPC. These results suggest that IPC and Allo act synergistically to protect cells against mitochondrial injury and preserve the hepatic energy metabolism during hepatic I/R.     

大鼠肢体缺血预处理对肝缺血/再灌注损伤的保护作用

目的：研究肢体缺血预处理对大鼠肝缺血/再灌注损伤是否具有保护作用。方法：雄性SD大鼠32只,随机分为对照组（S组）;缺血/再灌注组（I/R组）;经典缺血预处理组（IPC组）;肢体缺血预处理组（远端缺血预处理组,RPC组）。S组仅行开腹,不作其他处理;IPC组以肝缺血5min作预处理;RPC组以双后肢缺血5min,反复3次作预处理,2个预处理组及I/R组均行肝缺血1h再灌注3h。取血用于血清谷丙转氨酶（ALT）与血清谷草转氨酶（AST）检测。切取肝组织用于测定湿干比（W/D）、中性粒细胞（PMN）计数及观察显微、超微结构的变化。结果：与I/R组比较,IPC组,RPC组ALT,AST,W/D值,及PMN计数均明显降低（P〈0.01）,肝脏的显微及超微结构损伤减轻。结论：肢体缺血预处理对大鼠肝脏I/R损伤有明显的保护作用,强度与经典缺血预处理相当,其机制可能与抑制肝脏炎症反应、减轻肝脏水肿、改善肝组织微循环有关。     

缺血预处理及低温对幼兔心肌缺血/再灌注损伤的影响

目的：探讨缺血预处理(ischemic preconditioning,IP)及低温对幼兔心脏缺血／再灌注损伤的影响。方法：采用Langendorff离体心脏灌注模型,取3～4周龄幼兔心脏,分别给予不同次数的IP后使其在20℃低温下缺血或给予同样次数的IP后使其分别在不同低温下缺血。常温再灌注30min。记录心脏缺血／再灌注前后左心室功能指标,测定再灌注末心肌组织中ATP和丙二醛(MDA)含量,超氧化物歧化酶(SOD)及Ca^2 -ATP酶的活性。结果：再灌注末,IP2组左心室各功能指标的恢复率及心肌组织的ATP含量及Ca^2 -ATP酶的活性均显著高于Con组和IP3组;SIP1、SIP2组的左心室各功能指标的恢复率及心肌组织的ATP含量均分别显著高于SConn1组和SCon2组。其心肌组织MDA含量亦分别低于SCon1组和SCon2组。结论：IP可减轻低温缺血的幼兔心肌缺血／再灌注损伤,其效应与IP的次数和低温程度有关。     

缺血预处理对缺血再灌注后兔脊髓磷酸腺苷代谢的影响

目的：研究缺血参处理对缺血再灌注后兔脊髓磷酸腺苷代谢的影响。方法：往置入腹主动脉的Swan-Ganz导管气囊内注气造成兔腰髓缺血模型。将实验兔分为假手术组、缺血组和预处理组。应用反相高效液相色谱方法（reverse phase HPLC),对缺血再灌注后不同时间点腰髓组织中磷酸腺苷（ATP、ADP、AMP）的含量进行检测。结果：和假手术组相比,缺血组兔再灌后各时间点腰髓组织ATP含量有明显下降（P＜0．01）。与缺血组相应时间点相比,预处理组兔再灌注后腰髓组织ATP含量明显提高（P＜0．01）。结论：缺血预处理显著提高缺血再灌注后兔脊髓组织ATP含量,这可能是缺血预处理对脊髓缺血再灌注损伤产生保护作用的机制之一。     

Intrinsic A(1) adenosine receptor activation during ischemia or reperfusion improves recovery in mouse hearts

We assessed the role of A(1) adenosine receptor (A(1)AR) activation by endogenous adenosine in the modulation of ischemic contracture and postischemic recovery in Langendorff-perfused mouse hearts subjected to 20 min of total ischemia and 30 min of reperfusion. In control hearts, the rate-pressure product (RPP) and first derivative of pressure development over time (+dP/dt) recovered to 57 +/- 3 and 58 +/- 3% of preischemia, respectively. Diastolic pressure remained elevated at 20 +/- 2 mmHg (compared with 3 +/- 1 mmHg preischemia). Interstitial adenosine, assessed by microdialysis, rose from approximately 0.3 to 1.9 microM during ischemia compared with approximately 15 microM in rat heart. Nonetheless, these levels will near maximally activate A(1)ARs on the basis of effects of exogenous adenosine and 2-chloroadenosine. Neither A(1)AR blockade with 200 nM 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) during the ischemic period alone nor A(1)AR activation with 50 nM N(6)-cyclopentyladenosine altered rapidity or extent of ischemic contracture. However, ischemic DPCPX treatment significantly depressed postischemic recovery of RPP and +dP/dt (44 +/- 3 and 40 +/- 4% of preischemia, respectively). DPCPX treatment during the reperfusion period alone also reduced recovery of RPP and +dP/dt (to 44 +/- 2 and 47 +/- 2% of preischemia, respectively). These data indicate that 1) interstitial adenosine is lower in mouse versus rat myocardium during ischemia, 2) A(1)AR activation by endogenous adenosine or exogenous agonists does not modify ischemic contracture in murine myocardium, 3) A(1)AR activation by endogenous adenosine during ischemia attenuates postischemic stunning, and 4) A(1)AR activation by endogenous adenosine during the reperfusion period also improves postischemic contractile recovery.     

The effects of ischemic preconditioning on resting coronary flow and reactive hyperemia: involvement of A1 adenosine receptors

During the myocardial protection induced by ischemic preconditioning a reduction in myocardial metabolism occurs due to activation of the A1 adenosine receptors. This study investigates whether preconditioning changes both resting coronary flow and the magnitude of coronary reactive hyperemia and whether A1 adenosine receptors are involved in the observed changes. Experiments were performed in 14 goats (30-50 kg body weight). After the animals were anesthetized with ketamine, an electromagnetic flow-probe was used to record blood flow in the left circumflex coronary artery. Distal to the probe, an occluder was placed to produce ischemic preconditioning and reactive hyperemia. Preconditioning was obtained with two periods of 2.5 min of coronary occlusion separated from each other by 5 min of reperfusion. Coronary reactive hyperemia was obtained with 15 s of occlusion of the artery before and after preconditioning. In a group of goats before preconditioning 0.2 mg kg(-1) of 8-cyclopentyl-dipropylxanthine (CPX), an A1 adenosine receptor blocker, were given intravenously. In all animals ischemic preconditioning did not alter resting coronary flow, but, in the absence of A1 adenosine receptor blockade, reduced the reactive hyperemic response. The total hyperemic flow and the excess/debt flow ratio were reduced by about 25% and 30% respectively. The A1 adenosine receptor blockade "per se" did not cause any change in the resting flow and in the parameters of the reactive hyperemia. Unlike what observed in the absence of blockade, after CPX ischemic preconditioning was unable to reduce total hyperemic flow and the excess/debt flow ratio. The results suggest that ischemic preconditioning reduces the coronary hyperemic response by decreasing the myocardial metabolism through the activation of the A1 adenosine receptors.     

Both ischemic preconditioning and ghrelin administration protect hippocampus from ischemia/reperfusion and upregulate uncoupling protein-2

Background  

A major endogenous protective mechanism in many organs against ischemia/reperfusion (I/R) injury is ischemic preconditioning (IPC). By moderately uncoupling the mitochondrial respiratory chain and decreasing production of reactive oxygen species (ROS), IPC reduces apoptosis induced by I/R by reducing cytochrome c release from the mitochondria. One element believed to contribute to reduce ROS production is the uncoupling protein UCP2 (and UCP3 in the heart). Although its implication in IPC in the brain has been shown in vitro, no in vivo study of protein has shown its upregulation. Our first goal was to determine in rat hippocampus whether UCP2 protein upregulation was associated with IPC-induced protection and increased ROS production. The second goal was to determine whether the peptide ghrelin, which possesses anti-oxidant and protective properties, alters UCP2 mRNA levels in the same way as IPC during protection.     

Effect of modulating cardiac A1 adenosine receptor expression on protection with ischemic preconditioning

Activation of A(1) adenosine receptors (A(1)ARs) may be a crucial step in protection against myocardial ischemia-reperfusion (I/R) injury; however, the use of pharmacological A(1)AR antagonists to inhibit myocardial protection has yielded inconclusive results. In the current study, we have used mice with genetically modified A(1)AR expression to define the role of A(1)AR in intrinsic protection and ischemic preconditioning (IPC) against I/R injury. Normal wild-type (WT) mice, knockout mice with deleted (A(1)KO(-/-)) or single-copy (A(1)KO(+/-)) A(1)AR, and transgenic mice (A(1)TG) with increased cardiac A(1)AR expression underwent 45 min of left anterior descending coronary artery occlusion, followed by 60 min of reperfusion. Subsets of each group were preconditioned with short durations of ischemia (3 cycles of 5 min of occlusion and 5 min of reperfusion) before index ischemia. Infarct size (IF) in WT, A(1)KO(+/-), and A(1)KO(-/-) mice was (in % of risk region) 58 +/- 3, 60 +/- 4, and 61 +/- 2, respectively, and was less in A(1)TG mice (39 +/- 4, P < 0.05). A strong correlation was observed between A(1)AR expression level and response to IPC. IF was significantly reduced by IPC in WT mice (35 +/- 3, P < 0.05 vs. WT), A(1)KO(+/-) + IPC (48 +/- 4, P < 0.05 vs. A(1)KO(+/-)), and A(1)TG + IPC mice (24 +/- 2, P < 0.05 vs. A(1)TG). However, IPC did not decrease IF in A(1)KO(-/-) + IPC mice (63 +/- 2). In addition, A(1)KO(-/-) hearts subjected to global I/R injury demonstrated diminished recovery of developed pressure and diastolic function compared with WT controls. These findings demonstrate that A(1)ARs are critical for protection from myocardial I/R injury and that cardioprotection with IPC is relative to the level of A(1)AR gene expression.     

Noradrenaline dynamics in prolonged ischemia after ischemic preconditioning

AIM OF THE STUDY: To determine the effects of two-staged ischemic preconditioning on myocardial noradrenaline in prolonged ischemia and reperfusion. METHODS: Thirty-two male Wistar rats anesthetised with urethane randomly divided into 2 groups: group 1 (ischemic preconditioning group, n = 16), and group 2 (control, n = 16). Myocardial interstitial noradrenaline levels were measured using a microdialysis technique. Ischemic preconditioning was elicited by two episodes: 5 min of ischemia and 10 min of reperfusion. The intermittent occlusions were followed by prolonged occlusion (60 min) and reperfusion (60 min). RESULTS: An increase in interstitial noradrenaline was observed in 10 min of prolonged ischemia in group 2, and in 20 min in group 1. After 20 min of myocardial ischemia there was a significant difference between groups (p < 0.05) in interstitial noradrenaline levels. In control group, it was 60% higher. In reperfusion, noradrenaline levels decreased markedly in group 1. CONCLUSION: We suggest that ischemic preconditioning by two episodes: 5-min ischemia and 10-min reperfusion prevents excessive noradrenaline interstitial accumulation, perhaps, through protection of physiological uptake I carrier.     

Activation of volume regulated chloride channels protects myocardium from ischemia/reperfusion damage in second-window ischemic preconditioning

Activation of volume regulated chloride channels (VRCCs) has been shown to be cardioprotective in ischemic preconditioning (IPC) of isolated hearts but the underlying molecular mechanisms remain unclear. Recent independent studies support that ClC-3, a ClC voltage-gated chloride channel, may function as a key component of the VRCCs. Thus, ClC-3 knockout (Clcn3(-/-)) mice and their age-matched heterozygous (Clcn3(+/-)) and wild-type (Clcn3(+/+)) littermates were used to test whether activation of VRCCs contributes to cardioprotection in early and/or second-window IPC. Targeted disruption of ClC-3 gene caused a decrease in the body weight but no changes in heart/body weight ratio. Telemetry ECG and echocardiography revealed no differences in ECG and cardiac function under resting conditions among all groups. Under treadmill stress (10 m/min for 10 min), the Clcn3(-/-) mice had significant slower heart rate (648±12 bpm) than Clcn3(+/+) littermates (737±19 bpm, n=6, P<0.05). Ex vivo IPC in the isolated working-heart preparations protected cardiac function during reperfusion and significantly decreased apoptosis and infarct size in all groups. In vivo early IPC significantly reduced infarct size in all groups including Clcn3(-/-) mice (22.7±3.7% vs control 40.1±4.3%, n=22, P=0.004). Second-window IPC significantly reduced apoptosis and infarction in Clcn3(+/+) (22.9±3.2% vs 45.7±5.4%, n=22, P<0.001) and Clcn3(+/-) mice (27.5±4.1% vs 42.2±5.7%, n=15, P<0.05) but not in Clcn3(-/-) littermates (39.8±4.9% vs 41.5±8.2%, n=13, P>0.05). Impaired cell volume regulation of the Clcn3(-/-) myocytes may contribute to the failure of cardioprotection by second-window IPC. These results strongly support that activation of VRCCs may play an important cardioprotective role in second-window IPC.     

缺血预适应对大鼠肢体缺血/再灌注后小肠细胞凋亡的影响

目的：观察大鼠肢体缺血再灌注后小肠粘膜自由基及钙含量改变与细胞凋亡情况．以及缺血预适应对其变化的影响。方法：将雄性Wistar大鼠18只,随机分为对照（Control）组,缺血／再灌注（I／R）组和缺血预适应（IPC＋I／R）组,分别测定血浆和小肠组织超氧化物歧化酶（SOD）、黄嘌呤氧化酶（XOD）、丙二醛（MDA）的含量,小肠组织钙及线粒体钙含量;小肠组织的Bel-2和Bax蛋白的表达水平;检测小肠细胞凋亡情况。结果：肢体I／R后血浆和小肠粘膜SOD减少而XOD和MDA增加;小肠组织钙及线粒体钙含量增多;Bel-2蛋白表迭和Bax表达增多,但Bel-2／Bax比值降低;凋亡细胞增多。IPC减轻了I／R后引起的XOD、MDA含量的升高,并且增加了SOD的含量;减轻了组织和线粒体钙超载;Bel-2的表达则明显升高而Bax表达较I／R组明显减少,Bel-2／Bax比值升高;凋亡细胞减少。结论：肢体IR引起小肠粘膜自由基的增多,钙超栽,凋亡细胞增多;IPC可能通过减少自由基的产生及钙超载,抑制细胞凋亡而对肢体I／R继发的小肠功能损伤起保护作用。     

心肌缺血预适应循环血中微囊泡对大鼠心肌I/R损伤的作用

目的：研究心肌缺血预适应（IPC）大鼠循环血中微囊泡（MVs）对大鼠在体心肌缺血/再灌注（I/R）损伤的作用及相关机制。方法：反复短暂结扎/松开大鼠冠状动脉左前降支建立大鼠IPC模型,自腹主动脉取血,超速离心法分离循环血中的IPC-MVs,并对其进行流式鉴定。建立在体大鼠心肌I/R模型,股静脉注射IPC-MVs 7 mg/kg。HE染色观察心肌形态学变化,TTC染色检测心肌梗死范围,TUNEL染色检测心肌细胞凋亡率。比色法测定血清乳酸脱氢酶（LDH）活力,分光光度法测定心肌组织caspase 3活力,Western blot法检测心肌组织Bcl-2、Bax蛋白表达水平。结果：流式细胞术检测IPC-MVs浓度为4380±745个/μl。与I/R组比较,IPC-MVs能够减轻I/R大鼠心肌组织损伤,缩小心肌梗死范围（P<0.01）,减少心肌细胞凋亡数量（P<0.01）,明显降低血清LDH活力（P<0.01）,降低心肌组织caspase 3活力（P<0.01）,升高Bcl-2蛋白表达（P<0.01）,降低Bax蛋白表达（P<0.01）,升高Bcl-2/Bax比值（P<0.01）。结论：IPC-MVs显著减轻大鼠在体心肌I/R损伤,通过上调心肌组织中Bcl-2的蛋白表达,下调Bax的蛋白表达,升高Bcl-2/Bax比值,降低caspase 3活力而发挥心肌保护作用。     

缺血预适应对大鼠肢体缺血/再灌注后肺损伤的影响

目的:观察肢体缺血预适应对大鼠肢体缺血/再灌注(I/R)后肺损伤的影响并探讨其机制。方法:将雄性Wistar大鼠随机分为4组(n=8):对照组(C),肢体缺血/再灌注组(LI/R),缺血预适应组(IPC)和L-NAME组。各组大鼠均于肢体缺血4h再灌注4h处死,分别测定其动脉血氧分压(PaO2)和二氧化碳分压(PaCO2),血浆及肺组织丙二醛(MDA)、一氧化氮(NO)、内皮素(ET)含量,计算血浆NO/ET比值;以及肺湿干比(W/D)、肺系数(LI),肺组织髓过氧化物酶(MPO)含量。结果:大鼠LI/R后4h,PaO2明显降低;W/D、LI、血浆及肺组织的MDA、NO、ET和肺组织MPO活性均明显增加,而血浆NO/ET比值明显减小。与LI/R组比较,IPC组各项损伤指标明显减轻,NO水平升高,血浆NO/ET比值明显增大。与对照组和IPC组比较,L-NAME处理组,各项损伤指标数值明显增加,NO水平降低;血浆NO/ET比值明显减小,差异均具有显著性。各组大鼠PaCO2的变化无显著性。结论:缺血预适应对肢体缺血/再灌注后肺损伤具有保护作用,其机制可能与内源性NO合成增加有关。     

Proteomic analysis of intestinal ischemia/reperfusion injury and ischemic preconditioning in rats reveals the protective role of aldose reductase

Intestinal ischemia/reperfusion (I/R) injury is a critical condition associated with high morbidity and mortality. Studies show that ischemic preconditioning (IPC) can protect the intestine from I/R injury. However, the underlying molecular mechanisms of this event have not been fully elucidated. In the present study, 2-DE combined with MALDI-MS was employed to analyze intestinal mucosa proteomes of rat subjected to I/R injury in the absence or presence of IPC pretreatment. The protein content of 16 proteins in the intestinal mucosa changed more than 1.5-fold following intestinal I/R. These proteins were, respectively, involved in the cellular processes of energy metabolism, anti-oxidation and anti-apoptosis. One of these proteins, aldose reductase (AR), removes reactive oxygen species. In support of the 2-DE results, the mRNA and protein expressions of AR were significantly downregulated upon I/R injury and enhanced by IPC as confirmed by RT-PCR and western blot analysis. Further study showed that AR-selective inhibitor epalrestat totally turned over the protective effect of IPC, indicating that IPC confers protection against intestinal I/R injury primarily by increasing intestinal AR expression. The finding that AR may play a key in intestinal ischemic protection might offer evidences to foster the development of new therapies against intestinal I/R injury.