Pretreatment with bone morphogenetic protein-7 (BMP-7) mimics ischemia preconditioning following intestinal ischemia/reperfusion injury in the intestine and liver

Intestinal ischemia/reperfusion (I/R) injury has been shown to cause intestinal mucosal injury and adversely affect function. Ischemic preconditioning (IPC) has been shown to protect against intestinal I/R injury by reducing polymorphonuclear leukocyte infiltration, intestinal mucosal injury, and liver injury, and preserve intestinal transit. Bone morphogenetic protein 7 (BMP-7) has been shown to protect against I/R injury in the kidney and brain. Recently, microarray analysis has been used to examine the possible IPC candidate pathways. This work revealed that IPC may work through upregulation of BMP-7. The purpose of this study was to examine if pretreatment with BMP-7 would replicate the effects seen with IPC in the intestine and liver after intestinal I/R. Rats were randomized to six groups: sham, I/R (30 min of superior mesenteric artery occlusion and 6 h of R), IPC+R (three cycles of superior mesenteric artery occlusion for 4 min and R for 10 min), IPC+I/R, BMP-7+R (100 microm/kg recombinant human BMP-7), or BMP-7+I/R. A duodenal catheter was placed, and 30 min before sacrifice, fluorescein isothiocyanate-Dextran was injected. At sacrifice, dye concentrations were measured to determine intestinal transit. Ileal mucosal injury was determined by histology and myeloperoxidase activity was used as a marker of polymorphonuclear leukocyte infiltration. Serum levels of aspartate aminotransferase were measured at sacrifice to determine liver injury. Pretreatment with BMP-7 significantly improved intestinal transit and significantly decreased intestinal mucosal injury and serum aspartate aminotransferase levels, comparable to animals undergoing IPC. In conclusion, BMP-7 protected against intestinal I/R-induced intestinal and liver injury. Bone morphogenetic protein 7 may be a more logical surrogate to IPC in the prevention of injury in the setting of intestinal I/R.     

Delayed administration of alpha-melanocyte-stimulating hormone or combined therapy with BAY 11-7085 protects against gut ischemia-reperfusion injury

Gut ischemia-reperfusion (I/R) injury is a serious complication of shock. Previously we demonstrated that the administration of alpha-melanocyte-stimulating hormone (MSH) immediately before mesenteric I/R protected against postischemic gut injury. In this report, we tested the therapeutic efficacy of alpha-MSH on gut I/R (60 min ischemia, 6 h reperfusion) injury when given at different time points of reperfusion. Rats underwent sham surgery or were treated with saline or with alpha-MSH that was given 1, 2, or 4 h after superior mesenteric artery clamping. Vehicle-treated I/R rats exhibited severe mucosal injury and increased NF-kappaB DNA binding activity, myeloperoxidase (MPO) activity, and interleukin-6 and heme oxygenase-1 (HO-1) expression. In contrast, rats given alpha-MSH at 1 h of reperfusion, but not 2 h or 4 h, exhibited much less mucosal injury. Rats given alpha-MSH at 1 h or 2 h of reperfusion, but not 4 h, exhibited less MPO activity, NF-kappaB DNA binding activity, and interleukin-6 protein and even higher levels of heme oxygenase-1 than vehicle-treated rats. In addition, we found that combined use of alpha-MSH, a known inhibitor of IkappaBalpha tyrosine phosphorylation, with BAY 11-7085, an inhibitor of IkappaBalpha Ser 32,36 phosphorylation, abrogates gut MPO induction and tissue injury at early and late time points of reperfusion. Thus, alpha-MSH, an endogenous peptide with a favorable side-effect profile, is effective in treating experimental gut I/R injury when given early after the initial ischemia and may represent a candidate therapy for gut I/R in humans in whom recognition and treatment are often delayed.     

卡巴胆碱对肠部分缺血-再灌注损伤所致全身炎症反应和多器官功能障碍的影响

目的 观察肠道内给予卡巴胆碱对肠部分缺血-再灌注(I／R)损伤诱发全身炎症反应和多器官 功能障碍的影响及其机制。方法 大耳白兔75只,随机分为肠部分I／R组(n=25)、卡巴胆碱治疗组(n=25) 和假手术组(n=25)。阻断肠系膜上动脉(SMA)血流50％,并维持4 h,造成肠部分I／R损伤。卡巴胆碱治疗 组于SMA阻断后1 h经肠道内注入质量分数为3％的卡巴胆碱溶液(3 μg／kg);假手术组处理同肠部分I／R 组,但不阻断SMA。各组于SMA阻断前及阻断后2、4、6、8、24、48和72 h取动脉血,采用放射免疫法测定血 浆肿瘤坏死因子-α(TNF-α)含量,同时观察脏器功能及病理形态学改变。结果 肠部分I／R损伤后,血浆丙 氨酸转氨酶(ALT)、血肌酐(SCr)、肌酸激酶同工酶(CK-MB)、TNF-α水平均显著升高(P均<0.05);心、 肝、肺等脏器显示严重病理损害。肠道缺血期给予卡巴胆碱后,血浆内ALT、SCr、CK-MB和TNF-α水平显 著降低(P均<0.05),术后24~72 h心、肺、肝、小肠病理学损伤明显减轻。结论 肠道内给予卡巴胆碱能减 轻肠部分I／R损伤引起的机体炎症反应和病理损害,改善和保护脏器功能。     

Antithrombin III prevents 60 min warm intestinal ischemia reperfusion injury in rats

We investigated the effect of antithrombin III on 60 min warm intestinal ischemia-reperfusion (IR) injury in rats. Sprague-Dawley rats, weighing 220–250 g, were divided into three groups: group 1 sham-operated group (no IR injury, n=8), group 2 ischemic control group (control, Ringer’s lactate infused, n=8), group 3 Antithrombin III treated group (250 U/kg before ischemia, n=8). Intestinal ischemia was induced in rats by occluding the superior mesenteric artery for 60 min. Malondialdehyde (MDA) levels, myeloperoxi-dase activity (MPO) and mucosal damage were investigated after 120 min reperfusion. Elevated MDA levels and MPO activity and severe histopathological damage were observed in the control group compared with the sham group (P<0.05). Decreased MDA levels and MPO activity and less histopathological damage were detected in group 3 compared with the control group (P<0.05). Accumulation of lipid peroxidation products and neutrophils in mucosal tissues were significantly inhibited by antithrombin III treatment. We conclude that treatment with antithrombin III before intestinal ischemia prevents histological damage in rats.     

Antithrombin III prevents 60 min warm intestinal ischemia reperfusion injury in rats

We investigated the effect of antithrombin III on 60 min warm intestinal ischemia-reperfusion (IR) injury in rats. Sprague-Dawley rats, weighing 220-250 g, were divided into three groups: group 1 sham-operated group (no IR injury, n=8), group 2 ischemic control group (control, Ringer's lactate infused, n=8), group 3 Antithrombin III treated group (250 U/kg before ischemia, n=8). Intestinal ischemia was induced in rats by occluding the superior mesenteric artery for 60 min. Malondialdehyde (MDA) levels, myeloperoxidase activity (MPO) and mucosal damage were investigated after 120 min reperfusion. Elevated MDA levels and MPO activity and severe histopathological damage were observed in the control group compared with the sham group (P<0.05). Decreased MDA levels and MPO activity and less histopathological damage were detected in group 3 compared with the control group (P<0.05). Accumulation of lipid peroxidation products and neutrophils in mucosal tissues were significantly inhibited by antithrombin III treatment. We conclude that treatment with antithrombin III before intestinal ischemia prevents histological damage in rats.     

Effect of ischaemic preconditioning on hepatic oxygenation, microcirculation and function in a rat model of moderate hepatic steatosis

IPC (ischaemic preconditioning) may protect the steatotic liver, which is particularly susceptible to I/R (ischaemia/reperfusion) injury. Hepatic steatosis was induced in Sprague-Dawley rats with a high-cholesterol (2%) diet for 12 weeks after which rats were subjected to I/R (ischaemia/reperfusion; 45 min of lobar ischaemia followed by 2 h of reperfusion). Rats were divided into three study groups (n=6 each) receiving: (i) sham laparotomy alone, (ii) I/R, and (iii) IPC (5 min of ischaemia, followed by 10 min of reperfusion) before I/R. Hepatic extra- and intra-cellular oxygenation and HM (hepatic microcirculation) were measured with near-infrared spectroscopy and laser Doppler flowmetry respectively. Plasma liver enzymes and hepatic tissue ATP were measured as markers of liver injury. Histology showed moderate-grade steatosis in the livers. At the end of 2 h of reperfusion, I/R significantly decreased extra- and intra-cellular oxygenation concomitant with a failure of recovery of HM (21.1+/-14.4% of baseline; P<0.001 compared with sham animals). IPC increased intracellular oxygenation (redox state of the copper centre of cytochrome oxidase; P<0.05 compared with rats receiving I/R alone) and flow in HM (70.9+/-17.1% of baseline; P<0.001 compared with rats receiving I/R alone). Hepatocellular injury was significantly reduced with IPC compared with I/R injury alone (alanine aminotransferase, 474.8+/-122.3 compared with 5436.3+/-984.7 units/l respectively; P<0.01; aspartate aminotransferase, 630.8+/-76.9 compared with 3166.3+/-379.6 units/l respectively; P<0.01]. In conclusion, IPC has a hepatoprotective effect against I/R injury in livers with moderate steatosis. These data may have important clinical implications in liver surgery and transplantation.     

Pyrrolidine dithiocarbamate protects the small bowel from warm ischaemia/reperfusion injury of the intestine: the role of haem oxygenase

IR (ischaemia/reperfusion) injury of the intestine occurs commonly during abdominal surgery. We have previously shown that PDTC (pyrrolidine dithiocarbamate), an HO-1 (haem oxygenase-1) donor, improves intestinal microvascular perfusion. In the present study, we have investigated the effects of PDTC on the intestinal microcirculation following IR (ischaemia/reperfusion) injury of the intestine. Male Sprague-Dawley rats (n=72) were randomly assigned to four groups (n=18/group): (i) sham-operated group, who underwent laparotomy without induction of IR of the intestine; (ii) IR group, who were subjected to 30 min of superior mesenteric artery occlusion and 2 h of reperfusion; (iii) PDTC+IR group, who received PDTC prior to IR; and (iv) ZnPP group, who received the HO-1 inhibitor ZnPP (zinc protoporphyrin) followed by procedures as in group (iii). The ileum was evaluated for changes in tissue cytochrome c oxidase redox status, RBC (red blood cell) dynamics and leucocyte-endothelial interactions. The expression of HO-1 in the ileal tissue was examined at the end of the reperfusion. PDTC significantly improved the intestinal tissue oxygenation, mucosal perfusion index and RBC velocity compared with the IR and ZnPP groups. PDTC also decreased the leucocyte-endothelial interactions (P<0.05 compared with the IR and ZnPP groups). PDTC induced the expression of HO-1, whereas ZnPP abolished this effect.     

Peroxisome proliferator-activated receptor gamma mediates protection against cyclooxygenase-2-induced gut dysfunction in a rodent model of mesenteric ischemia/reperfusion

Cyclooxygenase (COX)-2 has been identified as an important mediator elaborated during ischemia/reperfusion, with pro- and anti-inflammatory properties having been reported. As the role of COX-2 in the small intestine remains unclear, we hypothesized that COX-2 expression would mediate mesenteric ischemia/reperfusion-induced gut injury, inflammation, and impaired transit and that these deleterious effects could be reversed by the selective COX-2 inhibitor, N-[2-(cyclohexyloxy)-4-nitrophenyl] methanesulphanamide (NS-398). Additionally, we sought to determine the role of peroxisome proliferator-activated receptor gamma (PPARgamma) in mediating protection by NS-398 in this model. Rats underwent sham surgery or were pretreated with NS-398 (3, 10, or 30 mg/kg) intraperitoneally 1 h before 60 min of superior mesenteric artery occlusion and 30 min to 6 h of reperfusion. In some experiments, NS-398 (30 mg/kg) was administered postischemia. Ileum was harvested for COX-2 mRNA and protein, PGE2, myeloperoxidase (inflammation), histology (injury), intestinal transit and PPARgamma protein expression, and DNA-binding activity. COX-2 expression and PGE2 production increased after mesenteric ischemia/reperfusion and were associated with gut inflammation, injury, and impaired transit. Inhibition of COX-2 by NS-398 (30 mg/kg, but not 3 or 10 mg/kg) not only reversed the deleterious effects of COX-2, but additionally induced expression and nuclear translocation of PPARgamma. NS-398 given postischemia was equally protective. In conclusion, COX-2 may function as a proinflammatory mediator in a rodent model of mesenteric ischemia/reperfusion. Reversal of gut inflammation, injury, and impaired transit by high-dose NS-398 is associated with PPAR activation, suggesting a potential role for PPAR-gamma in shock-induced gut protection.     

Fructose-fed rats are protected against ischemia/reperfusion injury

This study examines the relationship between insulin resistance (IR) induced by fructose feeding (FF) and susceptibility to myocardial ischemia/reperfusion injury (MI/R). Six-week-old male Sprague-Dawley rats were randomized into control (CON; n = 59) or FF (n = 58) groups. After 4 weeks, rats were further randomized into one of the following groups: placebo, ischemic preconditioning (IPC), 5-hydroxydecanoic acid (5-HD) (10 mg/kg), or 5-HD + IPC. Moreover, to determine the role of fructose, a second model of IR (Zucker obese) and rats fed fructose diet for 3 days (FF-3) were also subjected to MI/R. In all experiments, rats were subjected to 30 min of myocardial ischemia and 4 h of reperfusion. In rats randomized to placebo, infarct size was significantly reduced by FF (24 +/- 5%) compared with CON (54 +/- 1%, p < 0.05). Pretreatment with 5-HD did not alter the infarct size in CON (45 +/- 5%) but inhibited the protection afforded by FF (53 +/- 7%). IPC reduced the infarct size to an equivalent level in both groups, whereas 5-HD administration prior to IPC blunted the IPC effect. In Zucker obese rats, infarct size was significantly larger (57 +/- 4%) compared with lean controls (37 +/- 4%, p < 0.05). In FF-3 rats, infarct size was also decreased (20 +/- 2%, p < 0.01) compared with CON. This study suggests that fructose feeding affords protection against MI/R that is related to or mimics preconditioning. This protection is not consistent with other models of IR and is likely related to the fructose diet itself.     

多次缺血预处理对兔脊髓缺血性损伤后脊髓功能和形态学的影响

目的观察多次缺血预处理(IPC)对兔脊髓缺血再灌注损伤的保护作用。方法24只日本大白兔随机分为假手术组(A组)、缺血再灌注组(B组)和IPC保护组(C组),各组均为8只。A组不阻断主动脉,B组左肾下阻断主动脉45min,C组左肾下阻断主动脉5min,开放5min,反复4次后再阻断主动脉45min。术后进行后肢神经功能评分和针电极肌电图(EMG)的描记及脊髓组织形态学改变的观察。结果B组同A、C组相比,后肢EMG亦有显著性病理改变(P<0.01)。结论多次IPC对家兔脊髓缺血再灌注损伤具有快速保护作用。     

Nitric oxide is an essential mediator of the protective effects of remote ischaemic preconditioning in a mouse model of liver ischaemia/reperfusion injury

NO (nitric oxide) may protect the liver from IR (ischaemia/reperfusion) injury. RIPC (remote ischaemic preconditioning) also protects against liver IR injury; however, the molecular mediator(s) of RIPC are currently unknown. The aim of the present study was to assess the role of NO in hindlimb RIPC-induced protection against liver IR injury. Mice were allocated to the following groups: sham group; RIPC group (six cycles of 4×4?min IR of hindlimb); IR group [40?min lobar (70%) hepatic ischaemia and 2-h reperfusion]; RIPC+IR group (RIPC followed by IR group procedures); and C-PTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt]+RIPC+IR group [C-PTIO (a direct NO scavenger) was administered, followed by the RIPC+IR group procedure]. Hepatic MBF (microcirculatory blood flow) was measured throughout the experiment. Circulating NOx (nitrite and nitrate) levels, plasma liver transaminases, hepatic histopathological and TEM (transmission electron microscopy) studies were performed at the end of the experiment. NOx concentrations were significantly elevated (P<0.05) in the RIPC and RIPC+IR groups. Compared with liver IR alone, RIPC+IR preserved hepatic MBF during liver reperfusion (P<0.05). In contrast, C-PTIO+RIPC+IR reduced MBF compared with RIPC+IR (P<0.05). RIPC+IR reduced plasma transaminases (P<0.05), and histopathological and ultrastructural features of injury compared with IR alone. The protective effects of RIPC+IR in reducing liver IR injury were abrogated in the group that received antecedent C-PTIO (C-PTIO+RIPC+IR). In conclusion, NO is an essential mediator of the protection afforded by hindlimb RIPC against liver IR injury. The mechanisms underlying this protection involve preservation of the sinusoidal structure and maintenance of blood flow through the hepatic microcirculation.     

Ischemic preconditioning ameliorates ischemia- and reperfusion-induced intestinal epithelial hyperpermeability in rats

We hypothesized that ischemic preconditioning (IPC) would ameliorate ischemia (I) and reperfusion (R)-induced intestinal mucosal hyperpermeability and that this effect would be diminished by lowering local adenosine concentrations using adenosine deaminase (ADA). The small intestine of anesthetized rats (group 1; n = 6) was divided into six 10-cm segments (A1-F1) each perfused by a different set of mesenteric branches. Segments D1-F1 were subjected to 3 cycles of IPC (2 min I/5 min R). Segments A1, B1, and C1 were excised at baseline, after 60 min of I (160), and after 60 min of I followed by 60 min of R (160/R60), respectively. Segment D1 was excised immediately after the last cycle of IPC, E1 was excised at 160 after IPC, and F1 was excised at 160/R60 after IPC. In group 2 (n = 6), the intestine was divided into five 10-cm vascularly isolated segments (A2-E2). Segment A2 was resected at baseline. The lumen of the remaining segments was filled with ADA (32 U/50 cm). Segment B2 was removed at the end of the experiment having been exposed to ADA for 150 min (ADA150). Segments C2, D2, and E2 were subjected to IPC. Segment C2 was excised immediately thereafter. Segments D2 and E2 were excised at 160 and 160/R60, respectively. Intestinal permeability to fluorescein isothiocyanate-labeled dextran (molecular weight 4000 D) was assessed ex vivo by using an everted gut sac method. IPC ameliorated intestinal hyperpermeability induced by 160 (43.0+/-7.6 vs. 70.4+/-8.3 nLmin/cm2; P = 0.024) and 160/R60 (20.2+/-3.7 vs. 69.5+/-10.8 nL/min/cm2; P= 0.003). IPC prevented ischemia-induced reduction in villus height. Treatment with ADA partially reversed the protective effect of IPC on the changes in permeability and villus height induced by I/R. We conclude that IPC partially protects against mucosal barrier dysfunction in rats subjected to mesenteric I/R. Adenosine is a mediator of IPC in the gut mucosa, but other factors also may be important.     

Evaluation of intestinal preconditioning in a porcine model using classic ischemic preconditioning or lung recruitment maneuvers

To test the hypotheses that repeated brief intestinal ischemic insults would elicit an intestinal preconditioning response to a subsequent intestinal I/R injury and that a similar response would be elicited by repeated lung recruitment maneuvers (RMs). Randomized experimental controlled animal study. University hospital animal laboratory. Eighteen anesthetized pigs. Animals were randomized to one of three groups, with six animals in each group. Control group 75-min superior mesenteric artery (SMA) occlusion followed by 60-min reperfusion. Ischemic preconditioning group, three 5-min-long SMA occlusions preceding 75-min SMA occlusion and 60-min reperfusion. Recruitment maneuver (RM) group, three 2-min-long RMs preceding 75-min SMA occlusion and 60-min reperfusion. We measured systemic and mesenteric hemodynamic parameters, jejunal mucosal perfusion, net mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygenation. Every 15 min, jejunal microdialysate samples were collected and analyzed for glucose, lactate, and glycerol. Jejunal tissue samples were collected postmortem. After occlusion of SMA, regional parameters in all groups indicated abolished perfusion and gradually increasing intraluminal microdialysate lactate and glycerol levels. At reperfusion, regional parameters indicated mesenteric hyperperfusion, whereas microdialysis markers of mucosal anaerobic metabolism and cell injury decreased, although not reaching baseline. Histological examination revealed severe mucosal injury in all groups. There were no significant differences between groups in the observed parameters. No protective preconditioning response could be observed when performing repeated brief intestinal ischemic insults or repeated lung RMs before an intestinal I/R injury.     

运动预处理对心肌缺血再灌注损伤老龄大鼠心肌的影响

目的:观察运动预处理对心肌缺血再灌注损伤后老龄大鼠心功能、心肌梗死面积、心肌细胞超微结构及抗氧化能力的影响。方法:选择60只SPF级雄性SD老龄大鼠按照随机数字表法分为对照组(Con组)、缺血再灌注模型组(IR组)、运动预处理+缺血再灌注组(EP+IR组)、缺血预适应组(IPC组)、运动预处理+缺血预适应组(EP+IPC组),每组12只。Con组、IR组、IPC组不做特殊运动干预;EP+IR组、EP+IPC组接受运动预处理干预(采用电动动物实验跑台进行梯度运动训练,1次/d,5 d/周,共训练6周)。利用Langendorff装置制备老龄大鼠离体心肌缺血/再灌注模型,具体如下:Con组仅进行心肌离体灌流,持续平衡灌注180 min,不进行缺血操作;IR组平衡预灌注20 min,然后保持心脏温度恒定在37℃,通过控制灌流设备的三通阀,使全心缺血40 min,再复灌120 min;EP+IR组大鼠心脏离体后,模型制备方法同IR组;IPC组大鼠心脏离体后平衡灌注20 min,给予3次缺血预处理(短暂缺血5 min,再灌注10 min),之后缺血40 min,再复灌120 min;EP+IPC组大鼠心脏离体后,模型制备方法同IPC组。于再灌注前、再灌注30、60、120 min分别采用多导生理记录仪记录心脏功能变化;于再灌注结束后,采用TTC染色法测定心肌梗死面积,比色法检测冠脉流出液中LDH活性、心肌组织中MDA含量及SOD活力。结果:(1)心脏功能指标:与Con组同一时间点比较,IR组再灌注前、再灌注后30、60、120 min心功能各项指标[心率(CR)、左心室舒张压(LVDP)、左心室压力最大变化速率(±dp/dtmax)、冠脉流量(CF)]均明显降低(P<0.05)。与IR组同一时间点比较,EP+IR、IPC、EP+IPC组再灌注30、60、120 min心功能各项指标均明显升高(P<0.05)。与IPC组同一时间点比较,EP+IPC组再灌注30、60、120 min心功能HR、±dp/dt_max、CF均明显更高(P<0.05)。(2)心肌梗死面积:与Con组比较,IR组心肌梗死面积明显增大(P<0.05);与IR组比较,EP+IR、IPC、EP+IPC组心肌梗死面积明显缩小(P<0.05)。(3)LDH活性、MDA含量、SOD活力:与Con组比较,IR组LDH活性水平明显升高(P<0.05);与IR组比较,EP+IR、IPC、EP+IPC组LDH活性水平降低(P<0.05);与EP+IR、IPC组比较,EP+IPC组LDH活性水平明显更低(P<0.05)。与Con组比较,IR组MDA含量明显升高,SOD活力明显降低(P<0.05);与EP+IR、IPC组比较,EP+IPC组MDA含量明显更低,SOD活力明显更高(P<0.05)。结论:运动预处理可诱导老龄大鼠心肌IPC保护作用,能有效改善心肌缺血再灌注损伤老龄大鼠心脏功能,减小心肌梗死面积,减轻心肌细胞损伤,这可能与其降低心肌缺血/再灌注时心肌LDH活性、MDA含量,提高SOD活力,增强心肌抗氧化能力有关。     

Effect of corticosteroid prophylaxis on lipopolysaccharide levels associated with intestinal ischemia in cats

Ischemia of the intestines damages the permeability of the intestinal wall, allowing lipopolysaccharide (LPS) (endotoxin) to leak from the gut lumen into the blood circulation, causing shock and death. We measured LPS levels associated with corticosteroid treatment vs. no treatment in cats whose superior mesenteric artery had been occluded for 60 min. In untreated cats, the preocclusion mean plasma LPS concentration remained stable at 0.069 +/- 0.015 ng/ml. Toward the end of the occlusion period, mean plasma LPS rose to 0.239 +/- 0.032 ng/ml (p less than .01). Release of the clamp and reperfusion with oxygenated blood was followed within 20 min by a large rise in plasma LPS concentration to 0.825 +/- 0.11 ng/ml (p less than .01), which had returned to preocclusion levels about 80 min later. Methylprednisolone (30 mg/kg) was infused into a second group of cats 1.5 h before SMA occlusion. In these cats there was a complete inhibition of the LPS rise both during and after occlusion. These data suggest that the reported beneficial effect of corticosteroids in the treatment of septic shock may be mediated, in part, by reducing LPS leakage from the gut.     

Estrogen augments the protection of hypertonic saline treatment from mesenteric ischemia-reperfusion injury

Either estrogen or hypertonic saline (HTS) administration can decrease lung inflammation after ischemia-reperfusion. The present study investigated whether combined treatment with estrogen and HTS could provide further protection from mesenteric ischemia-reperfusion (MSIR) injury. Male C3H/HeOuJ mice were randomly segregated into the following groups: sham-operated (sham), vehicle treatment followed by MSIR (vehicle treated), estrogen treatment followed by MSIR (estrogen treated), HTS treatment and MSIR (HTS treated), and combined treatment of estrogen plus HTS and MSIR (combined treated). In MSIR, mice were subjected to mesenteric ischemia for 60 min followed by reperfusion for 30 min. The histology of the lung and the gut was obtained. Lung injury was evaluated by lung edema and myeloperoxidase (MPO) activity; lung protein expression of macrophage migration inhibitory factor (MIF), toll-like receptor-4 (TLR4), phosphorylated inhibitory κBα (p-IκBα), and inducible nitric oxide synthetase (iNOS) were assayed. Survival analysis was monitored after MSIR for 120 min. Compared with those in the sham-treated group, the lung water ratio, MPO activity, and expressions of MIF, TLR4, p-IκBα, and iNOS were significantly increased in the vehicle-treated group. Diminished MIF, TLR4, p-IκBα, and iNOS expressions were found in the estrogen-treated group, whereas suppression of p-IκBα and iNOS was found in the HTS-treated group. Treatment with estrogen or HTS decreased the lung water and MPO activity. The combined treatment of estrogen and HTS further significantly diminished p-IκBα and iNOS expression, lung edema, and MPO activity and improved the inflammation of the lung and the morphology of the gut in histology compared with the results of a single treatment of estrogen or HTS. Survival analysis showed significantly increased survival in the combination-treated group compared with survival in the HTS-treated group. In conclusion, compared with single-agent use, treatment combining estrogen and HTS further decreases lung p-IκBα and iNOS expressions, as well as the degree of lung injury. These effects may result in better rates of survival from MSIR injury.     

缺血预处理抑制大鼠胰腺移植缺血再灌注胰腺细胞凋亡:活性氧与线粒体DNA修复酶的作用

背景:缺血预处理可诱发机体内源性保护机制,可全面有效地防治器官移植缺血再灌注损伤.在胰腺移植过程中冷、热缺血均可导致移植胰腺缺血再灌注损伤,线粒体结构及功能与胰腺病变密切相关,近些年研究发现,线粒体DNA存在修复体系,其与线粒体DNA损伤之间的平衡决定了疾病的发生和转归.目的:观察缺血预处理对大鼠胰腺移植缺血再灌注损伤时的细胞凋亡的影响,分析线粒体DNA修复酶8-氧鸟嘌呤DNA糖基化酶和氧化应激在其中的变化规律及可能途径.方法:纳入健康雄性SD大鼠50只,其中20只为供体,10只为假手术组,另20只糖尿病造模后分为缺血再灌注组和缺血预处理组,每组10只.假手术组只行开、关腹手术,缺血再灌注组和缺血预处理组行异位全胰十二指肠移植.缺血再灌注组对应供体大鼠于获取供胰前以4℃ UW液灌洗20 min:缺血预处理组对应供体大鼠于获取供胰前阻断腹上动脉5 min,再灌注5 min,共2次.供胰均控制热缺血时间为15 min,冷缺血时间为180 min.再灌注后12 h检测血浆淀粉酶活性、血糖浓度及Caspase-3,9活化水平,流式细胞法检测腺泡细胞凋亡率,罗丹明123法检测线粒体膜电位,二氯荧光素法检测线粒体过氧化氢产生速率,高效液相色谱法检测线粒体DNA中8-氧鸟嘌呤质量浓度,荧光定量聚合酶链反应法检测8-氧鸟嘌呤DNA糖基化酶mRNA的表达,Westenn-blotting法检测细胞色素C释放、磷酸化Akt及线粒体8-氧鸟嘌呤DNA糖基化酶蛋白表达水平.结果与结论:缺血预处理可降低线粒体氧化应激,提高Akt磷酸化水平,从而上调8-氧鸟嘌呤DNA糖基化酶表达,减少线粒体DNA氧化损伤,抑制腺泡细胞凋亡,减轻移植胰缺血再灌注损伤.     

Ischemic preconditioning reduces intestinal epithelial apoptosis in rats

Recent experimental studies have described protective effect of ischemic preconditioning (IPC) on ischemia-reperfusion (I/R) injury of the intestine. We hypothesize that to reach a new point of view on the effect of IPC in intestinal barrier function, the relationship between I/R-induced mucosal injury and apoptosis must first be clarified. The present study was undertaken to investigate the role of IPC on intestinal apoptosis and probable contributions of bcl-2 expression to this process. We also investigated the effect of intestinal IPC on ileal malondyaldihyde levels. Forty-four male Wistar rats were randomized into four groups each consisting of 11 rats: sham-operated control, I/R group (30 min of superior mesenteric artery occlusion), IPC-I/R group (10 min of temporary artery occlusion prior before an ischemic insult of 30 min), and IPC alone group (10 min of preconditioning). Twenty-four hours later, ileum samples were obtained. Ileal malondyaldihyde levels were increased in the I/R group (31.9 +/- 18.8 vs. 106.8 +/- 39.8) but not in the IPC alone and IPC-I/R groups (38.1 +/- 13.6 and 44.7 +/- 12.7; P < 0.01). The number of apoptotic cells was significantly lower in IPC-I/R group than that of I/R group, and these findings were further supported by DNA laddering and M30 findings. Diminished bcl-2 expression observed in the ileal specimens of I/R group was prevented by IPC. Our results indicate that IPC may provide a protective effect on ileal epithelium and that this effect is probably the result of a significant increase in the expression of bcl-2 after the insult. The reversal of apoptosis by IPC might help preserving the vitality of intestinal structures that have a critical function, cessation of which often leads to multiorgan dysfunction syndrome.     

异丙酚对犬急性心肌缺血再有灌注损伤时血流动力学的影响

目的研究不同剂量的异丙酚对犬急性心肌缺血再灌注损伤时血流动力学的影响。方法杂种家犬18只随机分为NS组(生理盐水对照组,2ml