黄芪注射液对大鼠压疮缺血-再灌注损伤炎症反应的作用

目的探讨黄芪注射液(AI)对压疮缺血-再灌注(I/R)损伤的保护作用及其机制。方法将24只大鼠随机分成正常对照组、I/R组、AI组各8只,均行10%水合氯醛麻醉后,对照组不作处理,其他两组均于压疮装置上受压(施加34.96kPa压强),给予3个循环的I/R;AI组给予等容积的AI注射液,其他两组以生理盐水静脉注射。用酶联免疫法测定大鼠血清中肿瘤坏死因子-α,细胞间黏附分子1以及髓过氧化酶。结果三组上述3个指标含量比较,差异有统计学意义(均P<0.01),I/R组高于对照组及AI组。结论 AI对压疮I/R损伤具有保护作用,其机制可能与减轻I/R后炎症反应有关。     

Hypocapnia attenuates mesenteric ischemia-reperfusion injury in a rat model

PURPOSE: Hypocapnia, a recognized complication of high frequency oscillation ventilation, has multiple adverse effects on lung and brain physiology in vivo, including potentiation of free radical injury. We hypothesized that hypocapnia would potentiate the effects of mesenteric ischemia-reperfusion on bowel, liver and lung injury. METHODS: Anesthetized male Sprague-Dawley rats were ventilated with high frequency oscillation and were randomized to one of four groups, exposed to either mesenteric ischemia-reperfusion or sham surgery, and to either hypocapnia or normocapnia. RESULTS: All animals survived the protocol. Ischemia-reperfusion caused significant histologic bowel injury. Bowel 8-isoprostane generation was greater in ischemia-reperfusion vs sham, but was attenuated by hypocapnia. Laser-Doppler flow studies of bowel perfusion confirmed that hypocapnia attenuated reperfusion following ischemia. Plasma alanine transaminase, reflecting overall hepatocellular injury, was not increased by ischemia-reperfusion but was increased by hypocapnia; however, hepatic isoprostane generation was increased by ischemia-reperfusion, and not by hypocapnia. Oxygenation was comparable in all groups, and compliance was impaired by ischemia-reperfusion but not by hypocapnia. CONCLUSION: Hypocapnia, although directly injurious to the liver, attenuates ischemia-reperfusion induced lipid peroxidation in the bowel, possibly through attenuation of blood flow during reperfusion.     

Aging aggravates long-term renal ischemia-reperfusion injury in a rat model

Aim

Ischemia-reperfusion injury (IRI) has been considered as the major cause of acute kidney injury and can result in poor long-term graft function. Functional recovery after IRI is impaired in the elderly. In the present study, we aimed to compare kidney morphology, function, oxidative stress, inflammation, and development of renal fibrosis in young and aged rats after renal IRI.

Materials and methods

Rat models of warm renal IRI were established by clamping left pedicles for 45 min after right nephrectomy, then the clamp was removed, and kidneys were reperfused for up to 12 wk. Biochemical and histologic renal damage were assessed at 12 wk after reperfusion. The immunohistochemical staining of monocyte macrophage antigen-1 (ED-1) and transforming growth factor beta 1 (TGF-β1) and messenger RNA level of TGF-β1 in the kidney were analyzed.

Results

Renal IRI caused significant increases of malondialdehyde and 8-hydroxydeoxyguanosine levels and a decrease of superoxide dismutase activity in young and aged IRI rats; however, these changes were more obvious in the aged rats. IRI resulted in severe inflammation and tubulointerstitial fibrosis with decreased creatinine (Cr) clearance and increased histologic damage in aged rats compared with young rats. Moreover, we measured the ratio of Cr clearance between young and aged IRI rats. It demonstrated that aged IRI rats did have poor Cr clearance compared with the young IRI rats. ED-1 and TGF-β1 expression levels in the kidney were significantly higher in aged rats than in young rats after IRI.

Conclusion

Aged rats are more susceptible to IRI-induced renal failure, which may associate with the increased oxidative stress, increased histologic damage, and increased inflammation and tubulointerstitial fibrosis. Targeting oxidative stress and inflammatory response should improve the kidney recovery after IRI.     

The effect of astaxanthine on ischemia-reperfusion injury in a rat model

BackgroundWe aimed to compare biochemical and histopathological findings of astaxanthin's potential effects on oxidative stress in ischemia/reperfusion damage (I/R).MethodsThirty-two rats were randomly divided into four groups: control group; I/R group; I/R + treatment group; drug group. Astaxanthin was orally administered to groups C and D for 14 days. In groups B and C, the femoral artery was clamped for 2 h to form ischemia. The clamp was opened, and reperfusion was performed for 1 h. In all groups, 4 ml of blood sample through intracardiac puncture and gastrocnemius muscle tissue samples were collected. Serum and tissue samples were analyzed by measuring malondialdehyde (MDA), superoxide dismutase (SOD), total antioxidant capacity (TAC), and total oxidative level (TOL). Necrosis, inflammation, and caspase-3 in muscle tissue collected for histopathological examination were evaluated.ResultsTissue MDA, SOD and TOL values significantly differed between groups. Serum MDA, SOD, TOL and TAC values significantly differed between groups. On necrosis examination, there was a significant difference between groups B and C. Although signs of inflammation significantly differed between groups, there was no significant difference between groups A and C and groups A and D. Although there was a significant difference in caspase-3 results between groups, there was no significant difference between groups A and C.ConclusionsThe use of astaxanthin before and after surgery showed preventive or therapeutic effects against I/R damage.     

Diazoxide decreases ischemia-reperfusion injury in a rat model of lung transplantation

Background

Ischemia-reperfusion injury (IRI) is a significant factor contributing to primary graft failure in lung transplantation. Given a pivotal role of mitochondria in IRI-related molecular events, the effects of diazoxide, a selective opener of mitochondrial adenosine-5′-triphosphate (ATP)-sensitive potassium channels (mitoK_ATP), on IRI were investigated in a rat model of lung transplantation.

Methods

The 108 rats were randomly assigned to 5 groups; a sham-operated, 2 control, and 2 experimental groups that received either diazoxide alone or a combination of diazoxide with 5-hydroxydecanoate sodium salt. Lung injuries were assessed by multiple parameters at 2 hours or 24 hours after reperfusion, including oxygenation index, wet/dry weight ratio of transplanted lungs, lung morphology, as well as measurements of myeloperoxidase, malondialdehyde, total antioxidant capacity, tumor necrosis factor-α, and interleukin-6.

Results

Compared with the sham group, the 2 control groups revealed significant changes among most parameters of lung injury measured at either 2 hours or 24 hours after reperfusion. The extent of the changes was dramatically reduced by the administration of diazoxide. Importantly, the protective effect of diazoxide was almost completely reversed by co-administration of 5-hydroxydecanoate sodium salt, a selective blocker of mitoK_ATP.

Conclusions

These data provide evidence for substantial protective effects of diazoxide in an in vivo rat lung IRI model. Pharmacological modulation of mitoK_ATP may be a potential strategy to reduce IRI-induced primary graft failure in lung transplantation.     

Protective effects of immunosuppressants and steroids against ischemia-reperfusion injury in cremaster muscle flap at microcirculatory level

The sequential events between leukocytes and endothelium have significant implications in surgical procedures, trauma, vascular injury, and wound healing. These sequential events are mediated by free oxygen radicals, leukocytes, red blood cells, and endothelial cells. In this study, we investigated the protective effects of steroids and immunosuppressants against ischemia-reperfusion injury in cremaster muscle flaps at the microcirculatory level. In this experimental study, 50 male Sprague-Dawley rats, weighing about 120-130 g, were used. The rats were divided into five groups of 10 rats each: the control group (group 1, n = 10), methyl prednisolone group (group 2, n = 10), dexamethasone group (group 3, n = 10), cyclosporin A group (group 4, n = 10), and azathioprine (group 5, n = 10). Surgical procedures were divided into two stages. In the first stage, a cremaster muscle end-organ tube flap was created by extracting the testes and spermatic cord. The flap was placed into a subcutaneous tunnel in the anteromedial aspect of the ipsilateral limb. In the experimental groups, ischemia was performed by clamping the femoral artery and vein above and below the cremaster pedicle for 4 h. Then the clamps were removed, and perfusion of the cremaster muscle was allowed for 24 h. In the second stage, a round flap was obtained from the cremaster muscle tube-flap to evaluate microcirculation after 24 h of reperfusion, and dissected along its front wall using cauterization. Vessel diameter, red blood cell velocities, leukocyte activation, perfused capillaries, and endothelial edema index were measured and evaluated statistically. There was a significant decrease in the number of rolling, sticking, and transmigrating neutrophils of groups 2 (cyclosporin A), 4 (methylprednisolone), and 3 (azathioprine) (P < 0.05), whereas those of group 5 (dexamethasone) were not decreased (P > 0.05). There was a significant increase in the number of perfused capillaries of groups 2 (cyclosporin A), 4 (methylprednisolone), and 3 (azathioprine) (P < 0.05), nearly 0.75-, 0.5-, and 0.75-fold, respectively. We conclude that cyclosporin and azathioprine showed a protective effect on muscle tissue against ischemia-reperfusion injury by inhibiting leukocyte infiltration, and that methylprednisolone had a beneficial effect against ischemia-reperfusion injury by reducing the synthesis of eicosanoids, edema formation, and leukocyte infiltration. However, we believe that dexamethasone might have a salutary effect due to reducing the synthesis of eicosanoids, edema formation, and release of free oxygen radicals, but not due to leukocyte infiltration.     

大鼠肺缺血再灌注损伤长期存活模型的建立

目的 建立一种简单、稳定的大鼠肺缺血再灌注损伤(LIRI)长期存活模型.方法 将84只健康SD大鼠随机分为2组:Ⅰ组为假手术组,Ⅱ组为肺缺血再灌注组(每组n=42只).两组分别于开胸后、缺血1 h后再灌注0、2、4h、1、3、7 d取肺组织行髓过氧化物酶(MPO)活性、肺湿干比(W/D ratio)检测和肺泡Ⅱ型细胞(ATⅡ)的电镜超微结构评价;取支气管肺泡灌洗液检测肺通透性指数(LPI).结果 手术成功率达100%.Ⅱ组与Ⅰ组比较,缺血再灌注后2、4 h、1 d的MPO、LPI、W/D比差异均有统计学意义(P<0.01),开胸后、再灌注后0 h、3、7 d两组比较差异无统计学意义(P>0.05).ATⅡ的超微结构显示,再灌注4 h后损伤最严重,再灌注1 d即出现明显的修复过程,再灌注7 d基本恢复正常结构水平.结论 本模型简单、可靠,LIRI后相关肺损伤指标和ATⅡ超微结构损伤变化特点吻合.     

Attenuation of ischemia-reperfusion injury in a canine model of autologous renal transplantation

BACKGROUND: This study examined the potential therapeutic effects of a combination therapy consisting of 5-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR) and N-acetyl cysteine (NAC) to attenuate ischemia-reperfusion (I/R) injury in a canine model of autologous renal transplantation. METHODS: Male mongrel dogs (15-20 kg) underwent left nephrectomy followed by flushing and static preservation of the kidney in University of Wisconsin (UW) solution for 48 hr. The treatment group received AICAR (50 mg/kg) plus NAC (100 mg/kg) intravenously before the left nephrectomy. The compounds were added to the UW solution as well. All dogs underwent right nephrectomy 48 hr later followed by autotransplantation of the preserved left kidney. Treated dogs received a second dose of AICAR and NAC before implantation of the renal autograft. RESULTS: The treated dogs had excellent urine output posttransplant, with peak serum creatinine of 7.26 mg/dL on postoperative day (POD) 3 that normalized after 14 days. The control group were anuric and developed clinical symptoms of uremia on POD 1. Morphologic evaluation supported the protective effects of combination therapy. Immunohistochemical analysis revealed decrease of tumor necrosis factor-alpha, interferon-gamma, and inducible nitric oxide synthase; and TUNEL assay showed decreased apoptosis in the treated group. CONCLUSIONS: Combination therapy with AICAR and NAC attenuates renal I/R injury and improves the outcome of the transplanted kidney after prolonged cold preservation.     

Intrathecal morphine reduces infarct size in a rat model of ischemia-reperfusion injury

Systemically-administered morphine reduces infarct size in rat models of myocardial ischemia-reperfusion. We sought to determine whether much smaller doses of spinally-administered morphine offer a similar cardioprotective benefit. Barbiturate-anesthetized, open-chested, Wistar rats with chronic indwelling thoracic intrathecal catheters were instrumented for hemodynamic measurements and subjected to 30 min of coronary occlusion and 90 min of reperfusion. Myocardial infarct size was determined using triphenyl-tetrazolium staining. Rats were randomly assigned to receive intrathecal (IT) 0.9% saline (vehicle), IV morphine (0.3 mg/kg) plus IT saline, small-dose IT morphine (0.3 microg/kg), or large-dose IT morphine (3 microg/kg) 20 min before occlusion. IV and both doses of IT morphine reduced infarct size, defined as area of necrosis expressed as a percentage of area at risk (%AN/AAR), as compared with vehicle. The %AN/AAR group means were as follows: IV (n = 7), 30% +/- 6%; IT(small-dose) (n = 9), 30% +/- 5%; IT(large-dose) (n = 9), 18% +/- 4%; and vehicle (n = 10), 47% +/- 5%. There were no significant differences in infarct size among the morphine-pretreated rats. During ischemia-reperfusion, heart rate was unchanged from baseline in the IT(large-dose) group, whereas in the IT(small-dose), IV and vehicle groups, significant declines in heart rate occurred. Changes in arterial blood pressure were similar among groups. These results indicate that IT morphine reduces infarct size in rats, and this benefit is as great as that provided by IV morphine administration. IMPLICATIONS: Our findings suggest that spinally-administered morphine provides a previously unrecognized cardioprotective benefit. In anesthetized rats subjected to ischemia-reperfusion injury, we show that very small doses of intrathecal morphine reduce infarct size in rats, and this benefit is as great as that provided by much larger doses of IV morphine.     

Effects of FK3311 on pulmonary ischemia-reperfusion injury in a canine model

BACKGROUND: This study investigated the effects of a selective COX-2 inhibitor, FK3311, on warm ischemia-reperfusion (I/R) injury in the canine lung. MATERIALS AND METHODS: Sixteen adult mongrel dogs were used in this study. In the FK group (n = 8), FK (1 mg/kg) was administered intravenously 15 min before ischemia and 15 min before reperfusion. In the control group (n = 8), a vehicle was injected in the same manner. Warm ischemia was induced for 3 h by clamping the left pulmonary artery, veins, and bronchus. Five-minute clamping tests of the right pulmonary artery were performed before ischemia and 30 min after reperfusion. During the test, left pulmonary vascular resistance (L-PVR), cardiac output (CO), and arterial oxygen pressure (PaO(2)) were measured. The lung specimens were simultaneously harvested for wet-to-dry weight ratio (WDR) measurements, histopathological studies, and polymorphonuclear neutrophil (PMN) counts. Serum thromboxane (Tx) B(2) and 6-keto-prostaglandin (PG) F(1alpha) (stable metabolites of TxA(2) and PGI(2), respectively) were also measured 30 min after reperfusion. RESULTS: L-PVR, CO, PaO(2), and WDR were significantly (P < 0.05) better in the FK group than in the control group. Histological tissue edema was mild, and PMN infiltration was significantly (P < 0.05) reduced in the FK group compared to the control group. The serum TxB(2) levels were significantly (P < 0.05) lower in the FK group than in the control group, while 6-keto-PGF(1alpha) levels were not significantly (P < 0.05) reduced. Two-day survival rate was significantly (P < 0.05) better in the FK group than in the control group. CONCLUSIONS: FK has protective effects on pulmonary I/R injury stemming from marked inhibition of TxA(2).     

Erdosteine improves oxidative damage in a rat model of renal ischemia-reperfusion injury

The aim of the present study was to determine the effects of erdosteine, a new antioxidant and anti-inflammatory agent, on lipid peroxidation, neutrophil infiltration, and antioxidant enzyme activities in a rat model of renal ischemia-reperfusion (I/R) injury. Twenty-eight rats were divided into three groups: sham operation, I/R, and I/R plus erdosteine groups. After the experimental procedure, rats were sacrificed and kidneys were removed and prepared for malondialdehyde (MDA) levels, myeloperoxidase (MPO), xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD) activities. MDA level, MPO and XO activities were significantly increased in the I/R group. On the other hand, SOD and CAT activities were found to be decreased in the I/R group compared to the sham group. Pretreatment with erdosteine significantly diminished tissue MDA level, MPO and XO activities. Our data support a role for erdosteine in attenuation in renal damage after I/R injury of the kidney, in part at least by inhibition of neutrophil sequestration and XO activity.     

Attenuation of renal ischemia-reperfusion injury with selectin inhibition in a rabbit model

BACKGROUND: The selectin glycoproteins are involved in the pathogenesis of renal ischemia-reperfusion injury. We investigated the ability of glycyrrhizin, a known selectin inhibitor, to attenuate renal ischemia-reperfusion injury. METHODS: Eighteen New Zealand white rabbits underwent midline laparotomy with renal artery cross-clamping. After 30 minutes of reperfusion, group 1 (control, n = 10) animals received a saline infusion, while group 2 (GLY, n = 8) animals received a glycyrrhizin infusion. Renal function was compared between the two groups after 72 hours of reperfusion. A t test was utilized, with alpha set at P<0.05. RESULTS: Group 1 and group 2 animals had similar baseline renal function. However, after 72 hours of reperfusion, group 1 animals had a significantly higher mean blood urea nitrogen creatinine ratio than group 2 animals (P<0.01), indicating preserved renal function in rabbits treated with glycyrrhizin. CONCLUSIONS: Selectin blockade using glycyrrhizin attenuates renal ischemia-reperfusion injury when given 30 minutes after the onset of reperfusion in a rabbit model.     

Pretreatment with sildenafil alleviates early lung ischemia-reperfusion injury in a rat model

Background

Lung ischemia-reperfusion (I/R) injury plays an important role in lung transplantation. Less well known is the role of sildenafil in lung I/R injury; therefore, we attempted to determine whether sildenafil could alleviate lung apoptosis and tissue injury in a rat model.

Methods

Forty male Sprague-Dawley rats were randomized into four groups: saline + sham, saline + I/R, sildenafil + sham, and sildenafil + I/R groups. Three hours before the operation, each rat received normal saline or sildenafil (10 mg/kg) by lavage. The animals designed to I/R injury were subjected to 2 h of ischemia induced by occlusion of left pulmonary artery, veins, and bronchus, followed by reperfusion for 2 h. The lung tissue was harvested for the analysis of the expression of Bax, Bcl-2, p53, caspase 3, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and wet/dry (W/D) weight ratio.

Results

Compared with the saline + sham group, the saline + I/R group had significant increases in Bax, p53, Bax/Bcl-2 ratio, caspase 3, IL-6, TNF-α, and W/D weight ratio but a decrease in Bcl-2 (P < 0.05). Compared with the saline + I/R group, sildenafil + I/R group had significant decreases in Bax, p53, Bax/Bcl-2 ratio, caspase 3, IL-6, TNF-α level, and W/D weight ratio but an increase in Bcl-2 expression (P < 0.05). Compared with the sildenafil + sham group, there were significant increases in p53 and TNF-α expression in the sildenafil + I/R group (P < 0.05).

Conclusions

Pretreatment with sildenafil alleviates lung apoptosis and tissue injury in a rat model.     

Asialoerythropoietin has strong renoprotective effects against ischemia-reperfusion injury in a murine model

BACKGROUND: The renoprotective effect of erythropoietin (EPO) and the nonhematopoietic EPO, asialoEPO was investigated in a murine ischemia-reperfusion injury (I/R) model. METHODS: I/R was created by clamping the right renal pedicle for 60 min after left nephrectomy. Balb/c mice were divided into four groups (n=15 in each group): sham operation (Sham), vehicle treatment (Vehicle), EPO treatment (EPO), and asialoEPO treatment (AsialoEPO). EPO and asialoEPO were given at a dose of 500 IU/kg 30 min before I/R. Plasma creatinine (Cr), survival, and the number of apoptotic cells were analyzed. Protein expression was analyzed by Western blotting. RESULTS: Plasma Cr level was not significantly different at 6 hr after I/R. At 24 hr after I/R, the Cr (mg/dL) levels in Sham, Vehicle, EPO, and asialoEPO were 0.13+/-0.01, 1.24+/-0.70, 0.24+/-0.08, and 0.25+/-0.13, respectively (P<0.05). The numbers of apoptotic cells in these groups were 0.1+/-0.1, 98.9+/-42.6, 3.3+/-0.7, and 2.9+/-1.6, respectively (P<0.05). Western blotting revealed that in kidney tissue of mice treated with EPO and asialoEPO, p38-MAPK and the proapoptotic molecule Bad was decreased, and the antiapoptotic molecules Bcl-xL and XIAP were increased. Survival rates at 7 days after I/R injury in the Sham, Vehicle, EPO, and AsialoEPO groups were 100%, 21.4%, 23.1%, and 53.8%, respectively (P=0.05). CONCLUSION: EPO and asialoEPO attenuated renal dysfunction caused by I/R in mouse kidney at the same level, but only asialoEPO improved survival.     

静脉应用抑肽酶对大鼠肺移植模型缺血再灌注损伤的作用

目的 探讨静脉应用抑肽酶对肺移植后肺缺血再灌注损伤的作用和机制.方法 利用移植肺冷缺血14 h建立的大鼠肺移植缺血再灌注损伤模型,考察抑肽酶对缺血再灌注损伤的影响,并检测细胞因子等指标探讨机制.结果 抑肽酶组较对照组移植肺氧合好、湿干比小,同时支气管肺泡灌洗液中白细胞介素(IL)-2[(113±32)μg/L和(162±43)μg/L,P＜0.05]、血清中IL-8[(7.26±1.01)ng/L和(9.43±0.97)ng/L,P＜0.05]和肿瘤坏死因子(TNF)-α[(152.3±36.4)ng/L和(211.6±52.7)ng/L,P＜0.05]、肺组织中髓过氧化物酶活性[(2.36±0.62)U/g和(3.98±0.36)U/g,P＜0.05]都显著降低.结论 静脉应用抑肽酶能够减轻缺血再灌注损伤,机制可能包括:减少IL-2的释放、抑制TNF-α活化和IL-8产生,抑制中性粒细胞的聚集、激活和脱颗粒.     

The effect of body temperature in a rat model of renal ischemia-reperfusion injury

BACKGROUND: Renal ischemia-reperfusion injury (IRI) is an unavoidable event in renal transplantation; the effects of IRI can be seen in both the acute and long-term function of the transplanted organ. For this reason, research into the pathophysiology of ischemia-reperfusion is at the forefront of transplantation research. Animal models, particularly in the rat, provide a useful research tool in studying the intricacies of IRI and in evaluating new treatments. We describe a model of right nephrectomy and left renal clamping for 45 minutes and demonstrate the effects of temperature variation during the ischemic period. METHODS: Male Sprague-Dawley rats (under isoflurane anesthesia) underwent bilateral flank incision with removal of the right kidney and clamping of the left renal hilum for 45 minutes. The animals were divided into 3 groups (n=6): group 1 had the procedure performed on a heating mat with no temperature control facilities, group 2 used no heating mat, and group 3 used a rectal temperature-controlled homeothermic blanket system (Harvard Medical, United Kingdom). Temperature was taken every 5 minutes throughout the procedure and blood samples were taken on a daily postoperative basis via tail vein venepuncture. RESULTS: The average temperature at the end of the procedure in group 1 was 39.67 degrees C and the creatinine level at day 3 was 574+/-17.84, in group 2 the temperature was 32.6 degrees C and the creatinine level was 115+/-4.06, and in group 3 the temperature was maintained between 36.5 degrees C-37 degrees C and the serum creatinine level was 329+/-19.18. The temperature of the animal during the ischemia phase of IRI significantly affects the severity of injury. Relative hyperthermia resulted in more severe renal injury and unrecoverable acute renal failure, no source of heat led to a relative hypothermia, and reduction of renal injury. Use of the homeothermic heating blanket led to an increase in creatinine level by day 3, indicating a significant ischemic stimulus; however, by day 10 the creatinine level had returned to normal. CONCLUSION: This illustrates the importance of temperature as a variable in animal models of IRI and thus should be clearly stated in all experimental methods to ensure an appropriate ischemic stimulus and for adequate comparisons between various therapeutic interventions.