缺血预处理与缺血后处理对大鼠肾脏的保护作用对比观察

目的比较缺血预处理及缺血后处理对大鼠肾脏缺血再灌注损伤的保护作用。方法建立大鼠肾脏缺血（45min）再灌注模型。将24只健康Wistar大鼠随机分为假手术（SO）、缺血再灌注（Ia）、缺血预处理（IP）及缺血后处理（IPo）组,各6只。IP组于缺血前给予3周期的8min缺血、5min再灌注,IPo组于缺血后（再灌注前）给予6周期的10s再灌注、10s缺血。24h后观察血清肌酐（Cr）、尿素氮（BUN）、NO;取肾脏组织测定其超氧化物歧化酶（SOD）和丙二醛（MDA）。结果与IR组相比,IPo组及IP组血清Cr、BUN、NO和MDA水平降低（P〈0．05）,肾组织中SOD、MDA水平升高（P〈0．05）;IPo组与IP组相比,以上指标无显著性差异（P〉0．05）。结论IP和IPo对大鼠肾脏缺血再灌注都有保护作用,二者保护作用无区别。     

高渗盐水对大鼠肝脏缺血再灌注损伤的保护作用及其机制

目的 研究高渗盐水(7.5％氯化钠注射液)对大鼠肝脏缺血再灌注损伤的影响,并探讨其作用机制.方法 清洁健康雄性SD大鼠60只,体重220 ～ 260 g,随机分为4组:假手术组(Ⅰ组,Sham组)、缺血再灌注组(Ⅱ组,IR组)、缺血预处理组(Ⅲ组,IP组)、高渗盐水预处理组(Ⅳ组,HTS组)每组15只.制作70％肝脏缺血再灌注模型,肝脏缺血40 min,再灌注1、6、24h三个亚组,每个亚组5只.测定血清谷草转氨酶(AST)、谷丙转氨酶(ALT)、一氧化氮(N0)、内皮索-1(ET-1)、肿瘤坏死因子-α(TNF-α)和白介素-10(IL-10)的水平及再灌注6h后的肝组织病理学改变.免疫组化法检测再灌注6h的肝组织Bcl-2及Bax的表达;TUNEL法检测肝细胞凋亡指数(AI).结果 IR组、IP组及HTS组各时点AST、ALT、Bax及AI较同时点Sham组高,IL-10、NO且及Bcl-2水平较Sham组低,肝组织病理学损害重于Sham组;HTS组及IP组各时点AST、ALT、TNF-α、ET-1、Bax 及AI较同时点IR组低,HTS组最低,且IL-10、NO及Bcl-2水平较IR组高,HTS组最高,肝组织病理学损害明显轻于IR组,HTS组最轻.结论 HTS可以通过抑制血清TNF-α的升高、维持IL-10的水平,抑制肝组织Bax的表达,促进Bcl-2的表达,抑制肝细胞凋亡,从而减轻肝脏缺血再灌注损伤.     

黄芪对大鼠肝缺血再灌注损伤的影响

目的 探讨黄芪对大鼠肝缺血再灌注损伤的影响,以及与缺血预处理(IP)作用效果的比较.方法 清洁级健康雄性SD大鼠96只,随机分为假手术组、缺血再灌注组(IR组)、缺血预处理组(IP组)、黄芪组,每组又按再灌注时间(1、3、6、24 h)分为4个时相,每组各时相为6只.制作70%肝缺血再灌注模型,测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)水平;测肝组织髓过氧化物酶(MPO)含量;用免疫组化法检测IL-10、TNF-α表达;以及光镜及电镜观察大鼠肝形态学变化.结果 IR、IP、黄芪组ALT、AST、LDH和MPO含量均明显高于假手术组(P<0.01).与IR组相比,IP、黄芪组各个时相点的值均下降(P<0.05).与IP组比较,黄芪组各个时相点的值均降低(P<0.05).IR、IP、黄芪组肝组织TNF-α、IL-10的阳性细胞表达率均比假手术组高(P<0.05);与IR组比较,IP、黄芪组TNF-α的表达减少,而IL-10的表达增强(P<0.05);与IP组比较,黄芪组TNF-α的表达减少,IL-10表达增强(P<0.05).在光镜及电镜下观察肝形态学变化,可见IR组损伤甚为明显,IP及黄芪组损伤程度较IR组轻,黄芪组更轻,而假手术组肝形态正常.结论 IP和黄芪都可减轻缺血再灌注对肝脏的损伤,且后者较前者效果好.     

缺血后处理对大鼠肝脏缺血再灌注损伤的保护作用

目的探讨缺血后处理对大鼠肝脏缺血再灌注损伤的保护作用。方法将75只SD大鼠随机分为假手术组、缺血再灌注组和缺血后处理组,建立大鼠肝脏局部缺血再灌注模型。检测大鼠血清、肝组织丙二醛（MDA）、超氧化物歧化酶（SOD）水平,并行肝组织病理学和超微结构检查及免疫组化法检测内源性一氧化氮合成酶（eNOS）的表达。结果与缺血再灌注组相比,缺血后处理组血清ALT和AST水平及肝组织MDA明显降低（P＜0．01）,而SOD水平则显著升高（P〈0．01）;肝组织病理损伤减轻,在再灌注7min时IPO组肝组织eNOS蛋白表达比IR组增强。结论缺血后处理可通过抑制再灌注后氧自由基的过量生成和再灌注损伤保护激酶通路,从而减轻肝细胞损伤。     

温阳通脉方预适应对心肌再灌注损伤大鼠一氧化氮的影响

目的探讨温阳通脉方保护心肌缺血的机制是否通过模拟心肌缺血预适应（IP）而增加血浆一氧化氮（NO）的含量发挥作用。方法采用结扎大鼠冠状动脉左前降支，缺血30min，再灌注120min的方法建立缺血再灌注（IR）损伤模型，检测温阳通脉方组、IP组、IR组、假性颓处理组灌胃14d造模后血清NO含量，观察温阳通脉方对其的影响。结果温阳通脉方预处理组、IP组NO含量高于IR组（P〈0.05），温阳通骧方预处理组与IP组间比较无统计学意义。结论温阳通脉方预处理后，能增强大鼠心肌缺血再灌注损伤模型NO的含量，可能存在预适应样作用。     

茶多酚对大鼠肝脏缺血-再灌注损伤的保护作用

目的探讨茶多酚对大鼠肝脏缺血再灌注损伤的保护作用及其机制。方法健康雄性SD大鼠30只，随机均分为4组：假手术正常对照组6只；肝脏缺血再灌注损伤模型组8只；茶多酚低浓度于预组8只（75mg／kg）；茶多酚高浓度于预组8只（150mg／kg）．缺血30min再灌注60min检测肝组织MDA含量、GSH-PX活性及血浆ALT含量。光镜下比较各组肝组织损伤情况。结果肝缺血再灌注模型组ALT、MDA含量明显高于假手术正常对照组（P〈0．01），GSH-PX活力则降低（P〈0．01）；茶多酚低浓度及高浓度组ALT，MDA含量均明显低于肝缺血再灌注模型组（P〈0．01），而GSH-Px活力均高于肝缺血再灌注模型组（P〈0．01）；光镜观察茶多酚低浓度及高浓度预处理组肝细胞损伤明显小于肝缺血再灌注模型组。结论茶多酚对大鼠肝脏缺血再灌注损伤具有显著的保护作用。     

乌司他丁联合缺血预处理对大鼠肝缺血再灌注损伤的影响

目的探讨乌司他丁(UTI)预处理和缺血预处理(IPC)联合应用对大鼠肝缺血再灌注损伤的影响及可能的作用机制。方法选择雄性SD大鼠50只,随机分为5组,分别为对照(sham)组、缺血再灌注(IR)组、IPC组、UTI组、UTI联合缺血预处理(UCI)组。术后采集下腔静脉血并取肝组织标本,检测血清AST、ALT、TNFɑ,肝组织髓过氧化物酶(MPO)、NF-κB、肝组织湿干比(W/D)及光镜观察肝组织病理形态学变化。计量资料组间比较采用单因素方差分析,进一步两两比较采用LSD-t检验。结果所检测的血清ALT、AST、TNFα水平和肝组织MPO、NF-κB、W/D值,IR组、IPC组、UTI组、UCI组均明显高于sham组(P值均<0.05),而IPC组、UTI组、UCI组均明显低于IR组(P值均<0.05),UTI组明显低于IPC组(P值均<0.05),UCI组明显低于IPC组、UTI组(P值均<0.05)。肝脏病理学检查示IR组、IPC组、UTI组、UCI组与sham组比较,肝组织损伤明显(P值均<0.05),而IPC组、UTI组、UCI组均比IR组肝组织损伤程度轻(P值均<0.05),UTI组肝组织损伤轻于IPC组(P值均<0.05),UCI组肝组织损伤轻于IPC组、UTI组(P值均<0.05)。结论 UTI和UCI对肝脏缺血再灌注损伤均有保护作用,二者联合应用时,明显增强了对肝脏缺血再灌注损伤的保护效应。其发生机制可能与抑制了NF-κB表达,减少TNFɑ、MPO的释放,减轻了肝脏的炎症反应有关。     

温阳通脉方预处理对心肌缺血再灌注大鼠MDA及SOD的影响

目的 观察温阳通脉方预处理对大鼠心肌缺血再灌注损伤（IR）模型丙二醛（MDA）、超氧化物歧化酶（SOD）含量的影响，探讨温阳通脉方对大鼠再灌注心肌的保护机制。方法 采用结扎大鼠冠状动脉左前降支，缺血30min，再灌注120min的方法建立心肌缺血再灌注损伤模型；缺血5min，再灌注5min，反复3次后缺血30min，再灌注120min建立心肌缺血预适应（IP）模型。检测大鼠灌胃14d后温阳通脉方组、心肌缺血预适应组（IP组）、再灌注损伤纽（IR组）、假性处理组血清MDA、SOD含量。结果 温阳通脉方组、IP组MDA含量低于IR组，SOD高于IR组，差异有统计学意义（P〈0．05）。结论 温阳通脉方预处理后，能降低大鼠心肌缺血再灌注损伤模型MDA含量，升高SOD含量，减轻大鼠急性心肌缺血所致心肌损伤，其机制可能是通过模拟心肌缺血预适应参与心肌保护作用。     

NF-kB在大鼠肝缺血再灌注损伤中的活化及意义

目的探讨NFkB在肝缺血再灌注损伤过程中的作用。方法选择健康雌性Wistar大鼠24只,随机分为手术对照组,肝缺血90min组,肝缺血90min/再灌注120min组,每组8只。常规方法观察肝脏组织学改变,检测血清酶学水平和肝组织中髓过氧化物酶(MPO)含量,采用sABC免疫组织化学方法测定肝组织中NFkB的活化程度。结果手术对照组肝组织形态正常,无NFkB活化,肝功能酶学和MPO正常水平;缺血组动物肝细胞索排列紊乱,肝小叶变形,肝细胞和内皮细胞普遍水肿变性,NFkB呈中重度活化,血清酶学和MPO水平升高(P<0.01);肝缺血/再灌注组肝组织在缺血组改变基础上合并中央区局灶性肝细胞坏死,血窦内微血栓形成,汇管区中性粒细胞浸润,NFkB活化最为明显,血清酶学和MPO升高最为显著(P<0.01)。结论肝缺血再灌注时,NFkB被活化,使中性粒细胞组织浸润,对肝脏缺血再灌注损伤病理过程起到重要的作用。     

二氮嗪预处理对阻塞性黄疸肝脏缺血再灌注损伤的影响

将部分阻塞性黄疸大鼠分成缺血再灌注损伤组（对照组）、MPG处理组、二氮嗪预处理组（A、B、C组）。用二氮嗪预处理肝脏行缺血再灌注损伤实验，观察二氮嗪对肝脏缺血再灌注损伤有否保护作用。结果二氮嗪各预处理组与MPG组比较，血清谷丙转氨酶、谷草转肽酶、乳酸脱氢酶、细胞内丙二醛、超氧化物歧化酶及凋亡指数有统计学差异（P〈0．05）；与对照组比较无统计学差异。认为二氮嗪预处理对大鼠部分阻塞性黄疸肝脏缺血再灌注损伤无保护作用。     

Ischemic preconditioning protects the steatotic mouse liver against reperfusion injury: an ATP dependent mechanism

BACKGROUND/AIMS: Hepatic steatosis is a major risk factor for liver surgery and transplantation. The increased susceptibility of fatty livers to ischemic injury is associated with a necrotic form of cell death as opposed to apoptosis in lean animals, and is possibly related to low contents of ATP. Ischemic preconditioning, a brief period of ischemia prior to a prolonged period, protects the lean liver against ischemia through anti-apoptotic properties. We evaluated whether ischemic preconditioning also confers protection in the fatty liver and whether it protects against the ATP loss. METHODS: The effect of ischemic preconditioning was tested in steatotic and lean livers subjected to 75 min of ischemia and 4 or 24 h of reperfusion. Tissue ATP contents were assessed at various times, and a model of low hepatic ATP contents (starvation) was studied to assess the type of injury following ischemia and the effects of preconditioning. RESULTS: Ischemic preconditioning protected steatotic livers against massive necrosis. ATP levels were significantly higher before and after reperfusion in liver subjected to preconditioning when compared to controls. Liver with low baseline ATP levels (starvation) were also associated with necrosis, and were protected by ischemic preconditioning. CONCLUSIONS: Ischemic preconditioning mainly protects the fatty liver against necrosis possibly through preservation and restoration of tissue ATP contents.     

Preconditioning protects liver and lung damage in rat liver transplantation: role of xanthine/xanthine oxidase

This study was designed to evaluate whether ischemic preconditioning could confer protection against liver and lung damage associated with liver transplantation. The effect of preconditioning on the xanthine/xanthine oxidase (XOD) system in liver grafts subjected to 8 and 16 hours of cold ischemia was also evaluated. Increased xanthine levels and marked conversion of xanthine dehydrogenase (XDH) to XOD were observed after hepatic cold ischemia. Xanthine/XOD could play a role in the liver and lung damage associated with liver transplantation. This assumption is based on the observation that inhibition of XOD reduced postischemic reactive oxygen species (ROS) generation and hepatic injury as well as ensuing lung inflammatory damage, including neutrophil accumulation, oxidative stress, and edema formation. Ischemic preconditioning reduced xanthine accumulation and conversion of XDH to XOD in liver grafts during cold ischemia. This could diminish liver and lung damage following liver transplantation. In the liver, preconditioning prevented postischemic ROS generation and hepatic injury as well as the injurious effects in the lung following liver transplantation. Administration of xanthine and XOD to preconditioned rats led to hepatic ROS and transaminase levels similar to those found after reperfusion and abolished the protective effect of preconditioning on the lung inflammatory damage. In conclusion, ischemic preconditioning reduces both liver and lung damage following liver transplantation. This endogenous protective mechanism is capable of blocking xanthine/XOD generation in liver grafts during cold ischemia.     

Low-dose TNF-alpha protects against hepatic ischemia-reperfusion injury in mice: implications for preconditioning

Tumor necrosis factor alpha (TNF-alpha) is implicated in the pathogenesis of hepatic ischemia reperfusion injury but can also prime hepatocytes to enter the cell cycle. Ischemic preconditioning protects against ischemia-reperfusion (IR) liver injury and is associated with activation of nuclear factor kappaB (NF-kappaB) and cell cycle entry. We examined the pattern of TNF-alpha release during hepatic IR in the presence or absence of ischemic preconditioning, and we tested whether a single low-dose injection of TNF could mimic the biologic effects of ischemic preconditioning. In na?ve mice, hepatic and plasma levels of TNF-alpha rose during hepatic ischemia, reaching high levels after 90 minutes; values remained elevated during reperfusion until 44 hours. Following the ischemic preconditioning stimulus, there was an early rise in hepatic and serum TNF-alpha levels, but, during a second prolonged ischemic interval peak, TNF-alpha values were lower than in na?ve mice and declined to negligible levels by 2 hours reperfusion. An injection with 1 microg or 5 microg/kg body weight TNF-alpha 30 minutes prior to hepatic IR substantially reduced liver injury determined by liver histology and serum alanine aminotransferase (ALT) levels. As in ischemic preconditioning, TNF-alpha pretreatment activated NF-kappaB DNA binding, STAT3, cyclin D1, cyclin-dependent kinase 4 (cdk4) expression, and cell cycle entry, determined by proliferating cell nuclear antigen (PCNA) staining of hepatocyte nuclei. In conclusion, the hepatoprotective effects of "preconditioning" can be simulated by TNF-alpha injection, which has identical downstream effects on cell cycle entry. We propose that transient increases in TNF-alpha levels may substitute for, as well as, mediate the hepatoprotective effects of ischemic preconditioning against hepatic IR injury.     

Preconditioning protects against systemic disorders associated with hepatic ischemia-reperfusion through blockade of tumor necrosis factor-induced P-selectin up-regulation in the rat

Previous studies indicate that ischemic preconditioning protects against lung injury resulting from hepatic ischemia-reperfusion (I/R) through inhibition of tumor necrosis factor (TNF) release from Kupffer cells. The present study investigated whether this effect is limited to the lung or is a generalized systemic response and explores the molecular mechanisms involved. Hepatic I/R led to an increase in neutrophil accumulation in liver, lung, and splanchnic organs. Although preconditioning did not modify neutrophil infiltration in liver during reperfusion, it conferred protection against hepatic injury associated with I/R. In remote organs, preconditioning abrogated the increase in P-selectin up-regulation, preventing neutrophil infiltration and thus reducing the oxidative stress and microvascular disorders following hepatic I/R in these organs. Administration of Abs against P-selectin or TNF previous to ischemia had the same effects as preconditioning. The effects of preconditioning on the blockade of P-selectin up-regulation probably results from inhibition of systemic TNF release from Kupffer cells. Supplementation of TNF abolished the benefits of preconditioning, whereas the injurious effects of TNF were prevented by previous blockade of P-selectin. The results of the present study suggest that ischemic preconditioning protects the liver against I/R injury by a mechanism independent of adhesion molecule expression and neutrophil accumulation. In remote organs, however, hepatic preconditioning prevents inflammatory damage by reducing the systemic TNF release from the liver and thus preventing P-selectin up-regulation.     

Recent advances in liver preconditioning: Thyroid hormone, n-3 long-chain polyunsaturated fatty acids and iron

Liver preconditioning (PC), defined as an enhanced tolerance to injuring stimuli induced by previous specific maneuvers triggering beneficial functional and molecular changes, is of crucial importance in human liver transplantation and major hepatic resection. For these reasons, numerous PC strategies have been evaluated in experimental models of ischemia-reperfusion liver injury, which have not been transferred to clinical application due to side effects, toxicity and difficulties in implementation, with the exception of the controversial ischemic PC. In recent years, our group has undertaken the assessment of alternate experimental liver PC protocols that might have application in the clinical setting. These include thyroid hormone (T3), n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA), or iron, which suppressed liver damage due to the 1 h ischemia-20 h reperfusion protocol. T3, n-3 LCPUFA and iron are hormetic agents that trigger biologically beneficial effects in the low-dose range, whose multifactorial mechanisms of action are discussed in the work.     

Preconditioning methods in the management of hepatic ischemia reperfusion‐ induced injury: Update on molecular and future perspectives

Hepatic IR (ischemia reperfusion) injury is a commonly encountered obstacle in the post‐operative management of hepatic surgery. Hepatic IR occurs during ‘Pringle maneuver’ for reduction of blood loss or during a brief period of cold storage followed by reperfusion of liver grafts. The stress induced during hepatic IR, triggers a spectrum of cellular responses leading to the varying degrees of hepatic complications which in turn affect the post operative care. Different preconditioning methods either activate or subdue different sets of molecular signals, resulting in varied levels of protection against hepatic IR injury. Yet, there is a serious lacuna in the knowledge regarding the choice of preconditioning methods and the resulting molecular changes in order to assess the efficiency and choice of these methods correctly. This review provides an update on the various preconditioning approaches such as surgical/ischemic, antioxidant, pharmaceutical and genetic preconditioning strategies published during last six years (2009–2015). Further, we discuss the attenuation or inhibition of specific inflammatory, apoptotic and necrotic markers in the various experimental models of liver IR subjected to different preconditioning strategies. While enlisting the controversies in the ischemic preconditioning strategy, we bring out the uncertainties in the existing molecular targets and their reliability in the attenuation of hepatic IR injury. Future research studies would include the novel preconditioning strategies employ i) the targeted gene silencing of key molecular targets inducing IR, ii) hyper expression of beneficial molecular signals against IR via gene transfer techniques. The above studies would see the combination of these latest techniques with the established preconditioning strategies for better post‐operative hepatic management.     

Dual role of tumor necrosis factor-alpha in hepatic ischemia-reperfusion injury: studies in tumor necrosis factor-alpha gene knockout mice

Although hepatic ischemia-reperfusion (IR) injury is partially mediated by tumor necrosis factor-alpha (TNF), we recently found that low-dose TNF before IR is hepatoprotective. We examined the seemingly conflicting roles of TNF in mediating liver injury in a partial hepatic IR model using TNF gene knockout (TNF ko) mice to allow TNF replacement at specified times. Compared with wild-type mice, TNF ko mice exhibit minimal alanine aminotransferase release and few hepatonecrotic lesions during the early (time, 2 hours) and late (time, 24 hours) phases of IR. TNF ko mice differed from wild-type mice in that TNF ko mice exhibited no activation or induction of nuclear factor-kappa B, p38, cyclin D1, or proliferating cell nuclear antigen after IR. A single low-dose TNF injection 1 minute before the onset of hepatic ischemia restored hepatic IR injury in TNF ko mice. To clarify the importance of TNF for hepatoprotection, preconditioning (10 minutes of ischemia and 10 minutes of reperfusion) was performed before the onset of IR for TNF ko mice whose capacity to undergo IR injury had been restored by TNF replacement. Ischemic preconditioning failed to protect these mice from TNF-augmented IR injury; however, following the administration of intravenous TNF (1 microg per kg body weight, which mimics the early increase in hepatic and plasma TNF levels that is mobilized by ischemic preconditioning), significant hepatoprotection against both the early and late phases of TNF-augmented IR injury was observed. In conclusion, TNF appears to mediate both the early and late phases of liver injury in hepatic IR, but it also is an essential mediator of hepatoprotective effects brought about by ischemic preconditioning.     

Ischemic preconditioning-induced hyperperfusion correlates with hepatoprotection after liver resection

AIM:To characterize the impact of the Pringle ma-neuver (PM) and ischemic preconditioning (IP) on total blood supply to the liver following hepatectomies. METHODS: Sixty one consecutive patients who un-derwent hepatic resection under in flow occlusion were randomized either to receive PM alone (n = 31) or IP (10 min of ischemia followed by 10 min of reperfusion) prior to PM (n = 30). Quantification of liver perfusion was measured by Doppler probes at the hepatic artery and portal vein at various time points...     

Hepatic ischemic preconditioning in mice is associated with activation of NF-kappaB,p38 kinase,and cell cycle entry

A brief period of hepatic ischemia protects the liver against subsequent ischemia-reperfusion (IR) injury, but the mechanism of such preconditioning is poorly understood. We examined whether preconditioning activated nuclear factor kappa B (NF-kappaB), the stress-activated protein kinases (SAPK), c-Jun N-terminal kinase-1 (JNK-1) and p38, and entry into the cell cycle. We used a murine model of partial hepatic ischemia. Preconditioning was performed by clamping the vasculature for 2 to 20 minutes, and allowing reperfusion for 10 minutes before 90-minute ischemia or IR. As assessed by serum alanine aminotransferase (ALT) levels and liver histology, preconditioning periods of 5 and 10 minutes were highly protective against IR injury, whereas 2-, 15-, and 20-minute intervals were ineffective. Preconditioning was associated with entry of hepatocytes into the cell cycle within 2 hours of subsequent IR, as indicated by proliferating cell nuclear antigen (PCNA) nuclear staining, induction of cyclin D1 and numerous mitotic figures; in the absence of preconditioning, such changes were not seen until 24 hours. Preconditioning increased nuclear binding of NF-kappaB within 30 minutes of the subsequent ischemic interval, paralleled by degradation of inhibitory (binding) protein for NF-kappaB (IkappaBalpha). Ischemic preconditioning also activated p38 kinase and JNK-1, which are known to converge on cyclin D1 regulation. The protective effect of the preconditioning regimen was more closely associated with p38 kinase than JNK-1 activation. In conclusion, the hepatoprotective effects of ischemic preconditioning are associated with activation of NF-kappaB and SAPKs that are associated with entry of hepatocytes into the cell cycle, a critical biological effect that favors survival of the liver against ischemic and IR injury.