大鼠急性肠缺血后血浆D-乳酸的变化及其与肠粘膜损害的关系

目的观察肠缺血再灌注时门、体循环 D-乳酸的动态变化及其与肠粘膜损害的相关性。方法采用大鼠肠系膜上动脉阻断75分钟后松夹进行重灌注的模型,分别于术前,阻断末,松夹后0.5,2,6小时活杀动物,观察门静脉和体循环 D-乳酸水平、血浆内毒素含量及小肠病理形态学改变。结果肠缺血75分钟后大鼠门静脉 D-乳酸水平较伤前值显著上升(P<0.05),再灌注后呈进一步持续升高趋势。外周血 D-乳酸的改变与门脉血基本一致,各时相点与门脉血含量相比差异无显著意义(P>0.05)。相关分析结果显示,门静脉血浆 D-乳酸含量与肠粘膜损伤评分值呈显著正相关(r=0.415,P<0.01)。与此同时,大鼠肠缺血75分钟门静脉内毒素含量迅速上升,再灌注后2小时达峰值。结论急性肠缺血再灌注可致肠粘膜屏障破坏。使门、体循环 D-乳酸水平显著升高,其含量与小肠粘膜损害密切相关。因此,D-乳酸可作为新的血浆标志物应用于急性肠粘膜损害的早期诊断。     

缺血预处理对大鼠小肠缺血再灌注损伤的作用

目的 了解缺血预处理（ＩＰ）对小肠缺血的作用。方法 在不同缺血预处理的大鼠模型上，观察缺血再灌注后肠组织腺苷酸含量和肠粘膜损伤情况。结果 ＩＰ１组（预处理：１０分钟缺血１５分钟再灌注和ＩＰ２组（３分钟缺血５分钟再灌接以７分种１０分钟再灌）小肠的ＡＴＰ和总腺苷酸含量较对照组明显增高，肠粘膜损伤亦明显减轻（Ｐ〈０．０５）。．结论 ＩＰ１和ＩＰ２组的缺血预处理对小肠缺知再灌注损伤有一定的保护作用。     

生长激素对肠缺血-再灌注肠粘膜屏障功能的保护作用

目的 研究生长激素对肠缺血—再灌注肠粘膜屏障的保护作用。方法 观察小肠缺血—再灌注24h小肠粘膜形态学，腹腔淋巴结细菌培养、门静脉内毒素水平、小肠粘膜细胞凋亡的改变及生长激素对其改变的影响。结果 小肠缺血—再灌注24h，小肠粘膜细胞凋亡增加，绒毛高度和数量显著降低，门静脉内毒素水平升高，腹腔淋巴结细菌培养阳性升高；生长激素能显著改善上述改变。结论 生长激素对肠缺血—再灌注肠粘膜屏障具有明显保护作用。     

尼群地平对缺血再灌注肺脂质过氧化反应的影响

目的探讨肺缺血再灌注损伤的发病机理，观察尼群地平的防治效果。方法７２只大鼠随机分成假手术组、缺血再灌注组和治疗组，采用肺在体温缺血再灌注损伤模型，于缺血４５分钟、再灌注后１小时、２小时、４小时取损伤肺组织测丙二醛（ＭＤＡ）、超氧化物歧化酶（ＳＯＤ）和总钙含量。结果缺血再灌注组各时相肺组织ＭＤＡ含量上升（Ｐ＜０．０５），ＳＯＤ含量显著下降（Ｐ＜０．０５），总钙含量显著升高（Ｐ＜０．０５），尼群地平可减轻肺组织ＭＤＡ和组织总钙含量的升高（Ｐ＜０．０５）。结论钙超载和自由基反应共同参与了肺缺血再灌注损伤，二者可能相互影响，相互促进；尼群地平通过阻滞钙通道，影响自由基系统而对缺血再灌注肺起保护作用     

去白细胞血液预防家兔缺血心肌再灌注损伤的实验研究

用涤纶纤维滤器去除再灌注血液中的白细胞，旨在检验其对缺血心肌再灌注损伤的保护效应。３２只家兔随机分成对照组和实验组，分别用全血和去白细胞血再灌注－离体心脏在２８℃下缺血６０ｍｉｎ后再灌注２０ｍｉｎ。结果表明：对照组白细胞计数、ＣＶＲ、ＣＰＫ及ＣＰＫ－ＭＢ显著高于实验组（Ｐ〈０．００１～Ｐ〈０．０５）；ＳＯＤ活性下降，ＭＤＡ含量明显增高与实验组相比有显著差异，分别为Ｐ〈０．０２及Ｐ〈０．０５。线粒体     

牛磺酸对肠粘膜屏障保护作用的实验研究

目的：应用牛横酸保护失血性休克再灌注后肠粘膜屏障功能。方法：２４只家兔随机分为三组：牛磺酸治疗组（Ａ组），单纯休克组（Ｂ）、假手术组（Ｃ）、以硫代巴比妥酸比色法和原子吸收分光光度法测末端回肠粘膜ＭＤＡ和组织钙含量，并取体循环血做细菌培养，结果：Ｂ组肠粘膜ＭＤＡ和组织钙含量有明显升高，而Ａ组变化无显著性；再灌注半小时后Ｂ组细菌移位率明显高于Ｃ组（Ｐ〈０．０５）；光镜和电镜观察表明Ｂ组肠粘膜损伤明显重     

谷氨酰胺双肽保护肠粘膜屏障

传统的肠外营养和化疗药应激可导致肠粘膜形态及屏障功能障碍。为研究腹腔注射５－ＦＵ后谷氨酰胺双肽对肠粘膜形态及屏障功能的影响，作者将大鼠随机分成两组。对照组（ｎ＝１０）接受传统肠外营养液。双肽组（ｎ＝１０）接受传统肠外营养液加３％谷氨酰胺双肽，胃肠外营养维持７天；第４天腹腔注射５－ＦＵ，第３、７天测定肠粘膜通透性，第８天处死，测氨基酸谱、肠粘膜形态及细菌移位。结果：双肽组较对照组体重丢失少（Ｐ＜０．０５）。双肽组血浆谷氨酰胺浓度、空肠粘膜厚度和绒毛高度均高于对照组（Ｐ＜０．０５）。双肽组肠系膜淋巴结细菌移位率低于对照组（分别为３０％和９０％，Ｐ＜０．０５）。对照组和双肽组术后第３天（即化疗前）肠粘膜通透性无差异。乳果糖／甘露醇（Ｌ／Ｍ）分别为０．０２６±０．００６和０．０２２±０．００３。用５－ＦＵ后第３天（即第７天）对照组肠粘膜通透性明显升高。Ｌ／Ｍ为０．０４２±０．００５（Ｐ＜０．０５）。但双肽组Ｌ／Ｍ基本维持不变０．０２９±０．００２。作者认为：谷氨酰胺双肽强化的肠外营养对腹腔注射５－ＦＵ的大鼠，可维持小肠粘膜形态及屏障功能，减轻肠道细菌移位和肠粘膜通透性的升高。     

严重烫伤大鼠肠粘膜通透性改变及其机理

采用９９ｍＴｃ－ＤＴＰＡ血至肠腔清除率定量测定方法，观察大鼠严重烫伤后肠粘膜通透性的变化规律及血小板活化因子（ＰＡＦ）对其产生的影响，以探讨严重烫伤后肠粘膜屏障功能损害的病理生理过程及机理。结果表明：严重烫伤后肠粘膜通透性显著升高，与肠组织ＰＡＦ含量升高呈显著正相关（ｒ＝０．９４，Ｐ＜０．０１），ＰＡＦ拮抗剂治疗能明显降低肠粘膜通透性。提示，ＰＡＦ是导致严重烫伤后肠粘膜通透性升高的重要因素之一。     

早期肠道营养对烧伤后肠道功能的维护

选择平均烧伤面积４５％成人２１例，随机分为早期喂养（ＥＦ组）和延迟喂养组（ＤＦ组），探讨早期肠道营养对严重烧伤病人肠道功能的维护作用。结果表明内毒素在伤后４，８天ＥＦ组显著低于ＤＦ组（Ｐ＜０．０５～０．０１）；而ＳＯＤ则呈相反的变化，在伤后４，８天ＥＦ组显著高于ＤＦ组（Ｐ＜０．０１）；胃泌素和胃动素除伤后第１天的大多时相点ＥＦ组显著高于ＤＦ组（Ｐ＜０．０５～０．０１），而炎症介质ＴＮＦ和ＩＬ－８则呈相反的变化，两组间差异有显著意义（Ｐ＜０．０５～０．０１）。提示早期肠道营养可降低循环内毒素水平，减轻肠道缺血性再灌注损伤，削弱、阻滞“内毒素——炎症介质”对肠粘膜的损伤     

丹参对肢体缺血再灌注脂质过氧化反应影响的临床观察

目的：临床观察丹参对肢体缺血再灌注脂质过氧化反应的效果。方法：选择１６例肢体手术需充气带加压肢体止血的患者，随机分为对照组（ｎ＝８）和治疗组（ｎ＝８）。治疗组病人术前１０分钟静脉滴入复方丹参注射液（４００ｍｇ／ｋｇ），对照组病人给等量平衡液。肢体缺血前、再灌注后３０分钟、９０分钟、１８０分钟分别检测血ＭＤＡ、ＣＰＫ和ＳＯＤ。结果：肢体缺血再灌注３０分钟、９０分钟、１８０分钟与缺血前比较，血ＭＤＡ和ＣＰＫ含量升高，ＳＯＤ含量下降。治疗组缺血再灌注同时间，血ＭＤＡ含量明显低于对照组（Ｐ值＜０．０１）；ＣＰＫ值低于对照组（Ｐ值＜０．０５）；ＳＯＤ活性逐渐上升，１８０分钟高于对照组（Ｐ值＜０．０５）。结论：丹参有抗脂质过氧化作用，降低ＣＰＫ值，提高ＳＯＤ活性，能有效防治肢体缺血再灌注损伤。     

大鼠急性肠缺血后血浆D—乳酸的变化及期与肠粘膜损害的关系

OBJECTIVE: To determine the kinetics of plasma D(-)-lactate levels in both portal and systemic circulations, and to examine whether elevated plasma D(-)-lactate would correlate to intestinal injury in rats subjected to acute intestinal ischemia-reperfusion. METHODS: Anesthetized rats underwent 75 minutes of superior mesenteric artery occlusion followed by 6 hours of reperfusion. Plasma D(-)-lactate levels were measured by an enzymatic spectrophotometric assay. RESULTS: It showed that intestinal ischemia for 75 minutes resulted in a significant elevation in D(-)-lactate levels in portal vein blood compared to baseline values (P < 0.05). Plasma D(-)-lactate levels had a tendency to further increase after reperfusion up to 6 hours. Similar alterations in D(-)-lactate were also found in systemic circulation, there were no significant differences between the portal and systemic circulation at any time point. Moreover, the histopathological evaluation scores were significantly correlated to the portal D(-)-lactate levels in animals at various time points (r = 0.415, P < 0.01). In addition, a remarkable rise of endotoxin concentration within portal vein was already found at the end of 75-minute ischemia (P < 0.05), reaching a peak at 2 hours post-reperfusion. CONCLUSION: These data suggest that acute intestinal ischemia is associated with failure of mucosal barrier resulting in increased plasma D(-)-lactate levels in both portal and systemic blood. The subsequent reperfusion might cause further increase in D(-)-lactate levels, which correlated to the histopathological alterations. Plasma D(-)-lactate may be a useful marker of intestinal injury following both ischemia and reperfusion insults.     

Transhepatic lactate gradient in relation to liver ischemia/reperfusion injury during major hepatectomies.

Hepatectomies performed under selective hepatic vascular exclusion are associated with a series of events culminating in ischemia/reperfusion injury, a state that shares common characteristics with situations known to result in global or regional hyperlactatemia. Accordingly, we sought to determine whether lactate is released by the liver during hepatic resections performed under blood flow deprivation and what relation this has to a possible systemic hyperlactatemic state. After ethical approval, 14 consecutive patients with resectable liver tumors subjected to hepatectomy under inflow and outflow occlusion of the liver were studied. Lactate concentrations were assessed in simultaneously drawn arterial, portal venous, and hepatic venous blood before liver dissection and 50 minutes postreperfusion. Moreover, the transhepatic lactate gradient (hepatic vein - portal vein) was calculated to see if there was net production or consumption of lactate. Before hepatic dissection, the transhepatic lactate gradient was negative, suggesting consumption by the liver. Fifty minutes after reperfusion, this gradient became significantly positive, demonstrating release of lactate by the liver (0.12 +/- 0.31 vs. -0.38 +/- 0.30 mmol/L, P < 0.05). The magnitude of lactate release correlated with systemic arterial lactate levels at the same time point (r(2) = 0.63, P < 0.001). A weaker but significant correlation was demonstrated between the transhepatic lactate gradient postreperfusion and systemic arterial lactate levels 24 hours postoperatively (r(2) = 0.41, P = 0.013). A strong correlation between the transhepatic lactate gradient postreperfusion and peak postoperative aspartate aminotransferase values was also demonstrated (r(2) = 0.73, P < 0.001). The liver becomes a net producer of lactate in hepatectomies performed under blood flow deprivation. This lactate release can explain some of the systemic hyperlactatemia seen in this context and relates to the extent of ischemia/reperfusion injury.     

腹主动脉阻断导致内脏缺血再灌注损伤的研究

目的观察腹主动脉阻断所引起的肝、肾、小肠等内脏缺血再灌注损伤的改变。方法建立小猪腹主动脉阻断１小时的模型,检测在不同再灌注时点组织及血液中丙二醛（ＭＤＡ）和超氧化物歧化酶（ＳＯＤ）的变化,同时检测肝肾功能和动脉血气分析,观察动物术后的生存情况。结果与缺血前比较,大多数再灌注时点血、组织中ＭＤＡ明显升高,而ＳＯＤ明显降低（Ｐ＜０．０５）。在再灌注２小时,血中谷丙转氨酶（ＡＬＴ）、尿素氮（ＢＵＮ）、肌酐（ＣＲＥ）较缺血前明显升高（Ｐ＜０．０１）,代谢性酸中毒也极为明显。多数动物术后能够存活,但均出现下肢截瘫。结论腹主动脉阻断１小时能引起明显的内脏缺血再灌注损伤改变,多数内脏经处理后其损伤能够得到代偿恢复,而脊髓损伤恢复困难。     

Local intravascular coagulation and fibrin deposition on intestinal ischemia-reperfusion in rats

BACKGROUND: This study investigates intravascular coagulation and thrombotic obstruction in the splanchnic vasculature after intestinal ischemia in relation to epithelial integrity and function. METHODS: Intestinal ischemia was induced in rats by superior mesenteric artery occlusion for 20 or 40 minutes. Intestinal injury was assessed by histologic analysis, biochemical markers, and functional studies. During reperfusion, portal and systemic blood samples were collected to analyze activation of coagulation and fibrinolysis. RESULTS: Superior mesenteric artery occlusion resulted in mild to moderate intestinal injury. Twenty and 40 minutes of ischemia and 3 hours of reperfusion resulted in local intestinal thrombin generation and conversion of fibrinogen to fibrin, reflected by 3- and 4-fold increases in thrombin-antithrombin complex levels and a 3-fold elevation of fibrin degradation products (D-dimer), respectively. During reperfusion, after a short-lasting initial activation of local fibrinolysis, plasminogen activator activity was suppressed, as indicated by an approximately 4-fold increase in portal plasma levels of the plasminogen activator inhibitor. D-dimer levels showed that activation of coagulation and depression of fibrinolysis resulted in fibrin formation, which was confirmed to be intravascular fibrin deposition by histologic examination. CONCLUSIONS: Intestinal ischemia-reperfusion results in local intravascular coagulation and fibrin deposition.     

Changes of local and systemic hemorheological properties in intestinal ischemia‐reperfusion injury in the rat model

The aim of this study was to investigate intestinal ischemia‐reperfusion and its local and systemic hemorheological relations in the rat. Ten anaesthetized female CD outbred rats were equally divided into 2 experimental groups. (1) Ischemia‐reperfusion (I/R): the superior mesenterial artery was clipped for 30 minutes. After removing the clip, 60 minutes of the reperfusion was observed before extermination. Blood samples were taken from the caudal caval vein and from the portal vein before ischemia, 1 minute before and after clip removal, and at the 15th, 30th, and 60th minutes of the reperfusion. (2) Sham operation: median laparotomy and blood sampling were done according to the timing as in I/R group. Hematological parameters, red blood cell aggregation, and deformability were determined. Leukocyte count and mean volume of erythrocytes increased slightly but continuously in portal venous samples during the reperfusion period. Red blood cell aggregation values were higher in portal blood by the end of ischemia, and then became elevated further comparing to the caval venous blood. Both in caval and portal venous samples of I/R group red blood cell deformability significantly worsened during the experimental period compared to its base and Sham group. In portal blood red blood cell deformability was impaired more than in caval vein samples. Histology showed denuded villi, dilated capillaries, and the inflammatory cells were increased after a 30 minutes ischemia. In conclusion, intestinal ischemia‐reperfusion causes changes in erythrocyte deformability and aggregation, showing local versus systemic differences in venous blood during the first hour of reperfusion. © 2009 Wiley‐Liss, Inc. Microsurgery, 2010.     

Arterial levels of oxidized glutathione (GSSG) reflect oxidant stress in vivo

Neutrophil-related, oxidant-mediated injury to the pulmonary microvasculature appears to follow endotoxemia, cutaneous thermal injury, and ischemia-reperfusion injury to the liver or intestine. Glutathione is an important endogenous intracellular oxygen radical scavenger. Plasma concentrations of oxidized glutathione (GSSG) reflect oxidant injury resulting from an overdose of certain oxidatively metabolized drugs. The purpose of this investigation was to evaluate plasma GSSG as an indicator of oxidant stress resulting from activation of the endogenous inflammatory response. An established model of neutrophil- and oxidant-related acute lung injury following intestinal ischemia and reperfusion in rats was used. Intestinal ischemia was induced by clip occlusion of the superior mesenteric artery (SMA) for 120 min. Reperfusion resulted from SMA clip removal. Following reperfusion for 0, 15, or 120 min, plasma GSSG levels in portal vein, inferior vena cava (IVC), and aorta were obtained. Plasma GSSG was undetectable in sham animals and those with intestinal ischemia alone. Following reperfusion, all plasma samples had significant elevations in GSSG. Aortic plasma GSSG after 15 min of reperfusion was significantly elevated compared to both portal vein and IVC plasma GSSG. These data suggest that oxidant stress after intestinal reperfusion is reflected by elevations in plasma GSSG. The step up in plasma GSSG across the pulmonary vascular bed, a site of known oxidant injury, suggests that plasma GSSG may be a useful marker of oxidant stress in vivo, particularly with regard to the pulmonary microvasculature. This simple in vivo approach to assessing oxidant stress related to inflammatory tissue injury may have the potential to be of significant use in the clinical setting.     

Histamine: a promoter of xanthine oxidase activity in intestinal ischemia/reperfusion.

Xanthine oxidase (XO)-derived oxygen radicals are thought to play an important role in the intestinal injury resulting from ischemia and reperfusion. In vitro data shows enhanced XO activity in the presence of histamine. Histamine is known to be released during intestinal ischemia and reperfusion. The purpose of this study was to evaluate the relationship between histamine and XO in vivo in intestinal ischemia/reperfusion injury. Using an established model of gut ischemia and reperfusion, portal venous plasma was obtained and assayed for histamine levels, XO activity, and xanthine dehydrogenase (XD) activity following injury. Intestinal ischemia for 120 minutes resulted in a 200% increase in plasma histamine levels (263.4 +/- 36.9 nmol/mL control, v 548.7 +/- 35.1 nmol/mL experimental, P less than .05). Reperfusion for 15 minutes resulted in a further increase in plasma histamine (to 658.3 +/- 33.9 nmol/mL), compared with 120 minutes of ischemia alone. No significant change in plasma XO activity resulted after simple ischemia for 120 minutes. However, XO activity doubled within 15 minutes of reperfusion of the ischemic intestine (6.37 +/- 0.53 nmol O2- per milliliter per minute v 3.12 +/- 0.25 nmol O2- per milliliter per minute, P less than .05). Reperfusion for 60 minutes resulted in the maximal observed increase in plasma XO activity (9.49 +/- 0.67 nmol O2- per milliliter per minute). Analysis of XD activity demonstrated no significant decrease compared with controls until 120 minutes of ischemia and 60 minutes of reperfusion (1.62 +/- 0.49 nmol uric acid per milliliter per minute at 60 minutes of reperfusion, versus 5.02 +/- 0.52 nmol uric acid per milliliter per minute control, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lower Limb Ischemia-Reperfusion Injury Triggers a Systemic Inflammatory Response and Multiple Organ Dysfunction

Restoration of blood flow to an acutely ischemic lower limb may, paradoxically, result in systemic complications and unexpected mortality. We investigated the effect of acute ischemia-perfusion of the lower limb on cytokine production and end organ function. Plasma concentrations of tumor necrosis factor-alpha (TNF-a) and interleukin-6 (IL-6) were determined in five groups of male Wistar rats: control, 3 hours of bilateral hind limb ischemia alone, and 3 hours of bilateral hind limb ischemia followed by 1 hour, 2 hours, or 3 hours of reperfusion, respectively. In a second experiment, the effect of lower limb ischemia-reperfusion on remote organs (lung, liver, and kidney) was assessed biochemically and histologically. There was a significant increase in plasma concentrations of TNF-a in plasma of animals subjected to 3 hours of bilateral hind limb ischemia followed by 1 hour of reperfusion, 40.1 +/- 4.4 pg/ml, when compared with controls, 22.6 +/- 4.4 pg/ml, or animals in the ischemia-alone group, 16.3 +/- 5.2 (p <0.05). Plasma concentration of IL-6 increased progressively and significantly in animals subjected to bilateral hind limb ischemia followed by 1 hour of reperfusion, 720 +/- 107 pg/ml; 2 hours of reperfusion, 1987 +/- 489 pg/ml; or 3 hours of reperfusion, 6284 +/- 1244 (p <0.0001), compared with controls, 104 +/- 43 pg/ml; or animals in the ischemia-alone group, 140 +/- 55 pg/ml. In the study comparing portal and systemic concentrations of IL-6, systemic concentrations of IL-6, 967 +/- 184 pg/ml were significantly higher than those in the portal circulation 577 +/- 127 pg/ml (p <0.05). There was a significant increase in plasma concentrations of urea, creatinine, aspartate transaminase, alanine transaminase, and lactic dehydrogenase in reperfused animals compared with controls (p <0.001). Morbidity and mortality following reperfusion of the acutely ischemic limb may be a manifestation of multiple organ dysfunction caused by a systemic inflammatory response triggered by reperfusion of the ischemic extremities.     

门静脉高压犬肝缺血再灌注时肺循环血液动力学及NO/ET和PGI2/TXA2的变化

目的 评价门静脉高压犬肝缺血再灌注时肺循环血液动力学及肺循环一氧化氮(NO)/内皮素(ET)和前列腺素I2(PGI2)/血栓素A2(TXA2)的变化.方法 健康家犬12只,雌雄不拘,体重10～18 kg,随机分为2组(n=6):对照组和模型组.模型组采用部分结扎门静脉的方法 建立犬门静脉高压模型,12周后完全阻断门静脉、肝后下腔静脉30 min,再灌注60 min制备肝缺血再灌注模型.于第2次麻醉后即刻、肝缺血前即刻、缺血5、30 min、再灌注前即刻、再灌注5、10、15、30和60 min(T1-10)时记录心率(HR)、心输出量(CO)、中心静脉压(CVP)、肺动脉楔压(PAWP)和平均肺动脉压(MPAP),计算心脏指数(CI)、肺血管阻力(PVR)和肺血管阻力指数(PVRI),并计算T2-10时CI、CVP、MPAP、PAWP和PVRI相对于T1的变化幅度;于T2、T4和T9时测定肺动脉血浆NO、ET、TXA2和PGI2的浓度,并计算NO/ET和PCI2/TXA2比值.结果 两组肝缺血时CI、CVP、PVRI、PAWP和MPAP均降低,且模型组CI、CVP、PAWP、MPAP降低幅度低于对照组,两组再灌注时CVP、PAWP、MPAP和PVRI均升高,且模型组PAWP和PVRI升高幅度高于对照组(P<0.05或0.01);模型组肝缺血再灌注时肺动脉血浆NO浓度、NO/ET比值和肝缺血时肺动脉血浆TXA2浓度、PGI2/TXA2比值均低于对照组(P<0.01).模型组PVR与肺动脉血浆NO浓度呈负相关(r=-0.567,P<0.05).结论 门静脉高压犬肝缺血再灌注时肺动脉压升高,可能与肺循环NO水平降低、NO与ET失衡有关.