肝缺血再灌注后肝内血流动力学的变化

目的探讨肝脏缺血再灌注（I／R）后肝内分流（IHSF）和功能性肝血流（FHBF）的变化。方法健康雄性SD大鼠l2只，作右侧颈动脉、颈静脉插管；开腹后，经回结肠静脉作门静脉插管，分别用以输血、输液、给药、留样、检测等。大鼠经部分肝I／R制模后，随机分为2组（每组6只）：（1）正常对照组（对照组），术中只分离肝周围韧带，不作肝门阻断及再灌注。（2）缺血再灌注组（1／R组，实验组），进行45min的肝门阻断及60min的再灌注。然后两组均经门静脉输注D一山梨醇（10mmol／L，0．2mL／min），2min后同时取颈动脉、门静脉、肝静脉血各1mL。测定门静脉血流量（PVF）、肝动脉血流量（HAF）。计算肝脏山梨醇摄取率、FHBF和IHSF。结果两组PVF，HAF及总肝血流量（THBF）无明显统计学差异；与对照组比较，I／R组肝脏山梨醇摄取率和FHBF减少，IHSF增加（P〈0．01）。结论肝I／R后，肝内血流动力学变化表现为肝内门一体分流开放，功能性肝血流减少。     

门静脉注射异丙酚对家兔肝脏缺血再灌注损伤的保护作用

目的 探讨麻醉药物异丙酚经门静脉给药对肝脏缺血再灌注（I／R）损伤的保护作用及其可能机制。方法 将动物随机分为4组，每组8只。A组为假手术组，仅开关腹；B组为单纯阻断入肝血流30min再灌注60min（I／R）组；C组为I／R组＋颈静脉注射异丙酚组；D组为I／R组＋门静脉注射异丙酚组；检测各组家兔血清ALT和AST、肝组织及血液中内皮素-1（ET-1）和一氧化氮（NO）以及肝组织中ATP含量。结果 门静脉注射异丙酚可降低I／R期间血清ALT，AST及肝组织和血液中ET-1，提高肝组织和血液中NO及肝组织中ATP含量，其对肝I／R损伤的保护效应优于颈静脉给药。结论 经门静脉注射异丙酚对肝脏I／R损伤有明显的保护作用，此作用可能是通过调节ET-1与NO浓度的失衡及提高肝组织中ATP含量而实现的。     

内源性一氧化氮在非创伤性缺血预处理中对兔肺的保护作用

目的探讨内源性一氧化氮（NO）在非创伤性缺血预处理（N—WIP）中对兔肺缺血／再灌注（I／R）损伤的保护作用及可能机制。方法采用N-WIP及经典缺血预处理（C-IP）的动物模型，比较两种缺血预处理方法中内源性NO对兔肺在缺血／再灌注损伤中的保护效应。将40只大白兔随机平均分为4组：对照组、I／R组、C—IP组和NWIP组。对比观察各组血清及肺组织中NO2^-／NO3^-、丙二醛（MDA）含量及超氧化物歧化酶（SOD）活性以及肺湿／干重比。结果N—WIP组和C-IP组的兔肺再灌注后NO2^-／NO3^-含量均高于I／R组（P〈0．01），甚至高于对照组（P〈0．05）。两种缺血预处理组SOD活性均高于I／R组（P〈0．01），肺湿／干重比和MDA含量均低于I／R组（P〈0．05，P〈0．01）。结论N-WIP与C-IP对移植肺在缺血／再灌注损伤中具有同等强度的保护作用。其机制可能是通过诱发内源性一氧化氮（NO）舒张血管，从而起到保护血管内皮的效应。     

缺血预处理对肾脏的保护作用及其机制的实验研究

目的：在肾脏缺血预处理的动物实验模型中，探讨缺血预处理对肾脏的保护作用及其机制。方法：将36只小白兔随机分为4组，即对照组，缺血预处理组（IP），缺血再灌注组（I／R）和缺血预处理后再灌注组（IP＋I／R），分别检测各组动物血液中肌酐（Cr)和一氧化氮（NO）浓度，肾组织中一氧化氮合酶（NOS,eNOS，iNOS,nNOS)在肾组织中的表达及组织学变化。结果：急性肾缺血60min再灌注60min时，发现IP组及IP＋I／R组血液中Cr浓度变化与对照组之间差异无显著性意义（P＞0．05），但明显低于I／R组（P＜0．05），在IP组和IP＋I／R组血液中，NO浓度明显高于对照组和I／R组，eNOS阳性表达在IP组和IP＋I／R组明显高于I／R组和对照组（P＜0．01），iNOS和nNOS在肾组织中未见明显表达，组织学变化发现I／R组肾细胞发生明显变性坏死，而IP组和对照组未见明显改变，结论：缺血预处理在肾脏缺血再灌注中具有保护作用。而NOS可能参与了该作用机制。     

L-精氨酸对肝缺血再灌注损伤的保护作用及其机制

目的　探讨L 精氨酸 (L Arg)对肝脏缺血再灌注 (I/R)损伤的保护及其机制。 方法雄性SD大鼠随机分为 :假手术组 (Sham ) :大鼠开腹游离肝十二指肠韧带 ,不阻断 ;对照组 (Con trol) :单纯入肝血流阻断 ;Arg组 :肝缺血前 5min ,从大鼠阴茎背静脉 (PDV )注射L Arg 2 0 0mg/kg体重 ;Arg +L组 :肝缺血前 10和 5min ,依次从大鼠PDV注射L 硝基精氨酸甲酯 (L NAME) 30mg/kg体重和L Arg 2 0 0mg/kg体重 ;fmk组 :肝缺血前 5min ,从大鼠PDV注射N 笨甲基氧化碳酰 缬氨酸 丙氨酸 天冬氨酸 氟化丙酮 (ZVAD fmk) 15mg/kg体重。各组入肝血流阻断时间为 40min ,比较各组的谷丙转氨酶 (ALT)、Caspase 3活性、肝细胞凋亡数和 7d生存率。 结果　肝缺血 40min再灌注 6h ,Arg组的 7d生存率显著高于对照组和Arg +L组 (P <0 .0 5 )。Arg组ALT、Cas pase 3活性和肝细胞凋亡数明显低于对照组和Arg +L组 (P <0 .0 1)。Arg组的Caspase 3活性和肝细胞凋亡数略高于fmk组和假手术组 (P >0 .0 5 )。结论　L Arg对肝脏I/R损伤有良好的保护作用 ,其保护机理可能是通过一氧化氮 (NO)作用于Caspase 3并使其失活 ,从而抑制肝细胞凋亡的发生而实现的。     

异丙酚对肝缺血再灌注损伤犬肝细胞线粒体的作用

目的探讨异丙酚对肝缺血再灌注损伤犬肝细胞线粒体的作用及其机制。方法20只杂种犬随机分为4组（n=5）：假手术组（S组）、缺血再灌注组（I／R组）、小剂量异丙酚组（P1组）及大剂量异丙酚组（P2组）。以10ml／min速率静脉输注6％羟乙基淀粉150～200ml，同时从股动脉缓慢放血100～150ml，使平均动脉压（MAP）不低于85mmHg。S、I／R组静脉注射3％戊巴比妥钠30mg／kg、维库溴铵0．3mg／kg麻醉诱导，P1、P2组依次静脉注射异丙酚6mg／kg、维库溴铵0．3mg／kg麻醉诱导，气管插管后控制呼吸。S、I／R组间断静脉注射戊巴比妥钠维持麻醉，P1、P2组以血浆靶浓度6、12μg／ml靶控输注异丙酚维持麻醉30min后麻醉维持同S组。缺血期间回输自体血，维持MAP不低于80mmHg。I／R、P1组、P2组气管插管后30min制备肝缺血（缺血30min）再灌注模型。分别于缺血前即刻、缺血30min、再灌注60min抽取静脉血，测定血浆谷丙转氨酶（ALT）、谷草转氨酶（AST）及肝细胞线粒体Na^＋-K^＋-ATP酶活性，并在透射电镜下观察肝细胞线粒体的超微结构。结果肝缺血再灌注可导致血浆ALT、AST活性升高，肝细胞线粒体Na^＋-K^＋-ATP酶活性降低，肝线粒体损伤，异丙酚可减弱肝缺血再灌注导致的上述改变，以大剂量效果较好。结论异丙酚可减轻肝缺血再灌注损伤犬肝细胞线粒体损伤，呈剂量依赖性。     

L-精氨酸对大鼠胰腺移植缺血再灌注损伤的保护作用及其机制

目的探讨L-精氨酸（L-Arginine，L-Arg）对大鼠胰腺移植缺血再灌注（I／R）损伤的影响及其机制。方法SD大鼠作为供、受体行胰腺移植术，给予不同方式处理：假手术组（Sham）：只行开腹术；对照组（Control）：只行胰腺移植术，不行预处理；缺血预处理组（IPC）：在供胰切取前阻断血供10min，然后再灌注10min；L-精氨酸组（L-Arg）：行胰腺移植术，再灌注前先经下腔静脉注射L-Arg 10mg／kg体重；L-硝基精氨酸甲酯组（L-NAME）：供胰切取时阻断血供10min，再灌注10min；然后行移植术，在再灌注前，先经下腔静脉缓慢注射L-NAME 10mg／kg体重。各组手术完成后，于再灌注6h检测血清淀粉酶、肿瘤坏死因子-α（TNF-α）和一氧化氮（NO）水平，胰腺细胞凋亡指数、胰腺细胞bcl-2蛋白表达情况和胰腺组织病理改变。结果L-Arg和IPC都降低TNF-α水平（P〈0．01）和细胞凋亡水平（P〈0．01），NO水平升高（P〈0．01）。而L-NAME可阻断该保护效应。IPC和L-Arg均能激活bcl-2蛋白的表达。结论L-Arg可以模拟IPC对大鼠胰腺移植I／R损伤的保护作用，其机制与合成NO，激活bcl-2基因的表达有关。     

红花注射液对肝热缺血再灌注损伤保护作用的研究

目的 探讨红花注射液对大鼠肝热缺血再灌注损伤（IRI）的保护作用及其机制。方法 选用雄性SD大鼠，随机分成4组，每组6只。S组为假手术组。缺血再灌注组（I／R组）及红花预处理组（SPC组）在缺血前30min分别经肠系膜静脉注射生理盐水或红花注射液2mL／kg，而缺血预处理组（IPC组）缺血前30min阻断血流5min。再灌注后24h检测血清谷丙转氨酶（ALT）、谷草转氨酶（AST）水平；肝组织行HE染色，观察病理组织学改变及评分（根据Suzuki标准）；TUNEL法检测肝细胞凋亡；RT—PCR检测肝组织肿瘤坏死因子α（TNF—α）、巨噬细胞炎性蛋白-2（MIP-2）及细胞黏附因子-1（ICAM-1）mRNA的水平；Werstern blotting测定核转录因子κB（NF-κB）蛋白的表达。结果 再灌注24h后，与I／R组比较，SPC和IPC组血清ALT，AST水平、肝组织病理学半定量评分、肝细胞调亡指数、肝组织中TNF-α，MIP-2，ICAM-1 mRNA水平及NF-κB蛋白的表达均降低，差异均有显著性（P〈0.05）；SPC组与IPC组比较。上述各项指标差异均无统计学意义（P〉0．05）。结论 红花注射液通过下调前炎性因子TNF—α，MIP-2及ICAM—1 mRNA的水平及抗细胞凋亡作用，可减轻移植肝IRI。     

血浆一氧化氮对大鼠肝缺血预处理的影响

目的：探讨促进或抑制一氧化氮（NO）的合成对大鼠肝脏缺血预处理（IPC）保护作用的影响。方法：大鼠肝脏经缺血再灌注（I／R，R组）、IPC（P组）、左旋精氨酸（L－Arg，A组）促进或左旋单甲基精氨酸（L－NMMA，N组）抑制NO合成及假手术（C组）后，观察2、24h及1周后血浆NO、天冬氨酸氨基转移酶（AST）及丙氨酸氨基转移酶（ALT）以及大鼠死亡率及肝脏组织病理改变。结果：A组累计死亡率低于R组及N组（P＜0．05）。A组NO水平在2h后明显高于P组（P＜0．01）；N组在2h及24h后均低于P组（P＜0．05）及A组（P＜0．01），1周后与P组、A组及R组差异无显著性（P＞0．01），但明显高于C组。A组及P组的血浆ALT在2h及24h后均显著低于N组（P＜0．05），而N组与R组差异无显著性（P＞0．05），1周后，A组、P组及N组间差异无显著性，均低于R组（P＜0．05）。结论：增加NO的产生，可以明显增强IPC对肝脏的保护作用，抑制NO合成并不能完全阻断这种保护作用，提示NO是IPC保护机制中的一个重要但非唯一的因素。     

异氟烷预处理对大鼠肝窦内皮缺血再灌注损伤的影响

目的 研究异氟烷预处理对大鼠肝窦内皮常温缺血再灌注（I/R）损伤的影响,并探讨线粒体ATP敏感性钾通道（Mito-KATP）在其中的作用。方法 48只健康成年雄性SD大鼠,随机分为6组（n=8）。假手术组（S组）：进腹后仅分离韧带但不阻断血流;对照组（C组）：进腹后行部分肝脏缺血60min再灌注90min;异氟烷预处理组（Iso组）：吸入1．5%（1MAC）异氟烷30min,停止吸入10min后行I/R;5-HD＋Iso组：在吸入异氟烷前10min静脉注射5-羟葵酸（5-HD）10 mg/kg;二氮嗪组（Dia组）：I/R前10min静脉注射二氮嗪5mg/kg;5-HD＋Dia组：I/R前20min静脉注射5-HD 10mg/kg,10min后静脉注射二氮嗪5mg/kg。各组再灌注90min时测定血清谷丙转氨酶（ALT）的活性和透明质酸（HA）的浓度;以硝酸还原酶法检测肝组织一氧化氮（NO）含量,放免法检测内皮素（ET）含量;免疫组化法检测细胞间粘附分子-1（ICAM-1）的表达水平;光镜和电镜下观察肝组织病理学改变。结果 （1）与S组比较,C组血清ALT活性、HA浓度、肝组织ET含量和ICAM-1表达水平均升高,而肝组织NO含量降低（P＜0．05）。（2）异氟烷和二氮嗪预处理能抑制I/R引起的血清ALT活性及HA浓度、肝组织ET含量及ICAM-1表达水平的升高和肝组织NO含量的降低（P＜0．05）。（3）光镜和透射电镜检查提示Iso组和Dia组I/R所致的肝窦内皮细胞损伤减轻。（4）5-HD可完全阻断二氮嗪预处理对肝窦内皮的保护作用,但只能部分阻断异氟烷预处理对肝窦内皮的保护作用。结论 1．5%异氟烷预处理30min可减轻大鼠肝窦内皮缺血再灌注损伤,其部分机制通过开放Mito-KATP。     

Propofol reduces nitric oxide-induced apoptosis in testicular ischemia-reperfusion injury by downregulating the expression of inducible nitric oxide synthase

Background: The aim of the present study was to investigate the underlying mechanisms in the preventive effects of intravenous anesthetics on testicular ischemia–reperfusion injury.
Methods: Forty male Wistar Albino rats were randomly assigned to four groups of 10 rats each. Anesthesia was induced and maintained with thiopental in groups 1 and 2 and with propofol in groups 3 and 4. Groups 2 and 4 received left testicular ischemia (torsion) for 1 h and reperfusion (detorsion) for 24 h. Groups 1 and 3 (control groups) had no testicular torsion and detorsion. At 24 h of reperfusion, animals were killed and ipsilateral testes were removed for determination of tissue nitric oxide (NO) levels and immunohistochemical evaluation of endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), and apoptosis protease-activating factor 1 (APAF-1).
Results: Between groups 1 and 3, there were no differences in tissue NO levels and eNOS, iNOS, and APAF-1 expressions. iNOS and APAF-1 expressions were markedly increased in group 2, but these parameters were at the mild to moderate level in group 4 at 24 h of reperfusion. Also, elevated expression of iNOS was accompanied by a high NO production in group 2 compared with group 4. Although eNOS expressions were increased in both the groups (groups 2 and 4), there were no significant differences between these groups.
Conclusions: Propofol as an anesthetic agent may attenuate germ cell-specific apoptosis and decrease NO biosynthases through downregulation of iNOS expression in an animal model of testicular torsion and detorsion.     

Renal damage in rats induced by myocardial ischemia/reperfusion: Role of nitric oxide

BACKGROUND: It has been demonstrated that myocardial ischemia/reperfusion (MI/R) causes renal damage. However, the mechanism underlying this damage in kidneys during revascularization of myocardium is unclear. Direct renal ischemia/reperfusion has been implicated in the induction of inducible nitric oxide synthase (iNOS) that leads to increase production of nitric oxide (NO). Recently, excessive production of NO has been found to be involved in causing renal injury by formatting peroxinitrite (ONOO(-)). The aim of this study was to investigate whether NO has a role in this damage, using aminoguanidine (AMG), a known iNOS inhibitor and an antioxidant, in rats undergoing MI/R. METHODS: Male Wistar rats were used for the experiments (n = 7 each group). In the MI/R group, the left coronary artery was occluded for 30 min and then reperfused for 120 min; the same procedure was used for the AMG group, with the additional step of AMG (200 mg/kg) administered 10 min prior to ischemia. A control group underwent sham operation. At the end of the reperfusion period, all rats were killed and their kidneys removed for biochemical determination and histopathological analysis. RESULTS: Myocardial ischemia/reperfusion in the rat kidney was accompanied by a significant increase in malondialdehyde and NO production, and a decrease in glutathione content. Administration of AMG reduced malondialdehyde and NO production and prevented depletion of glutathione content. These beneficial changes in the biochemical parameters were also associated with parallel changes in histopathological appearance. CONCLUSION: These findings suggest that MI/R plays a causal role in kidney injury and AMG exerts renal-protective effects, probably by inhibiting NO production and antioxidant activities.     

一氧化氮对全胃肠外营养肝脂肪变性的保护作用

目的探讨一氧化氮(NitricOxide,NO)对全胃肠外营养(TotalParenteralNutrition,TPN)引起的肝脂肪变性的作用。方法30只Wistar大鼠随机分为5组A组，正常对照；B组，TPN；C组，TPN+精氨酸；D组，TPN+N     

Study of L—arginine—nitric oxide pathway in ischemiareperfusion injured limbs in rats

OBJECTIVE: To observe the change of nitric oxide (NO) levels in the blood and the morphological change of the muscles in the limbs of rats during the (IR) injury and after being intervened by L-arginine (L-Arg) and L-nitroarginine (L-NNA). METHODS: Sixty-six male Sprague-Dawley (SD) rats were used an d grouped into the normal controls, the sham injury controls, the IR injury group and the intervention groups (L-Arg group and L-NNA group). After 6 hours of ischemia, followed by reperfusion for 3, 12 or 24 hours, the samples in the IR injury group were obtained. The rats in the intervention groups were given L-Ar g (100 mmol/L) and L-NNA (10 mmol/L), respectively, through the abdominal cavity. Then the anterior tibial muscle in the right limb was obtained for histological examination, the anterior tibial muscle in the left limb for ultrastructure observation and the blood for assay of NO in all the rats. NO was assayed by indirect measurement of NO(2)(-)/NO(3)(-) with Griess method. RESULTS: There was no significant difference of NO between the normal controls and the sham injury controls (P>0.05). But NO significantly decreased in the IR injury group (P<0.01), and further decreased with reperfusion (P<0.01) and reached the lowest point at 12 hours after reperfusion. The level of NO in the L-Arg group was significantly higher than that in the IR injury group ( P<0.01), but was not significantly different from that in the controls (P>0.05). In the L-NNA group, NO decreased to the undetectable level (P<0.01). Histological examination and ultrastructure observation showed the muscles were normal in the control groups. After 6 hours of ischemia, the skeletal muscles displayed injuries, and they were most severely injure d after 12 hours of reperfusion. In the L-Arg group, the skeletal muscles were less injured, while in the L-NNA group, the injury was similar to that in the I R injury group. CONCLUSIONS: When the limbs of the rats sustain IR, NO in the blood decreases. Meanwhile, the muscles in the limbs are injured. When L-Arg is given, NO in the blood is restored and the muscles are protected. When L-NNA completely inhibits NO, no protection of the muscles is shown.     

一氧化氮合酶在肝癌缺血再灌注后细胞凋亡中的作用

目的　研究缺血再灌注后肝癌组织中一氧化氮 (NO)及一氧化氮合酶 (NOS)在细胞凋亡中的作用。方法　建立肝脏肿瘤和缺血再灌注模型 ,除测定NO和NOS含量外 ,并以荧光脱氧核苷酸末端转移酶介导的dUTP缺口末端标记法 (TUNEL)观察其细胞凋亡情况。结果　缺血再灌注后 ,两种组织中的NO均呈下降趋势 ,而总一氧化氮合酶 (NOS)明显升高 (P <0 .0 1) ,肝脏组织中的诱导型一氧化氮合酶 (iNOS)含量明显降低 ,但肝癌组织中iNOS含量明显升高 (P <0 .0 5 )。肝癌组织的凋亡细胞明显多于肝脏组织 (P <0 .0 1)。结论　缺血再灌注后肝脏组织和肝癌组织的NO、iNOS的改变是造成细胞凋亡的重要因素且对肝癌组织的影响更为显著。     

Differential nitric oxide synthase expression during hepatic ischemia-reperfusion

BACKGROUND: In recent years the important role of nitric oxide in hepatic ischemia-reperfusion injury has been increasingly recognised. The prevailing consensus is that reperfusion injury may be partly the result of decreased production of nitric oxide from endothelial nitric oxide synthase and excessive production of nitric oxide from the inducible isoform. We therefore undertook this study to characterize the expression of different nitric oxide synthase isoforms during hepatic reperfusion. METHODS: Male Wistar rats (n = 6) were subjected to 45 minutes of partial hepatic ischemia (left lateral and median lobes) followed by 6 hours of reperfusion. Control animals (n = 6) were subjected to sham laparotomy. The expression of endothelial and inducible nitric oxide synthase was examined using immunohistochemistry and Western blotting. Liver sections were also stained with nitrotyrosine antibody, a specific marker of protein damage induced by peroxynitrite (a highly reactive free radical formed from nitric oxide). RESULTS: Liver sections from all the control animals showed normal expression of the endothelial isoform and no expression of inducible nitric oxide synthase. Livers from all the animals subjected to hepatic ischemia showed decreased expression of endothelial nitric oxide synthase, and all but one animal from this group showed expression of the inducible isoform both in inflammatory cells and in hepatocytes. Western blotting confirmed these findings. Staining with the antinitrotyrosine antibody was also confined to five liver sections from animals subjected to hepatic ischemia. CONCLUSIONS: During the reperfusion period after hepatic ischemia, endothelial nitric oxide synthase is downregulated while inducible nitric oxide synthase is expressed in both hepatocytes and inflammatory cells. The presence of nitrotyrosine in livers subjected to hepatic ischemia-reperfusion suggests that the expression of inducible nitric oxide synthase plays an important role in mediating reperfusion injury in this model.     

Inhibition of nitric oxide synthase reduces renal ischemia/reperfusion injury

BACKGROUND: The role of nitric oxide (NO) production because of inducible nitric oxide synthase (iNOS) in the pathogenesis of renal ischemia/reperfusion (I/R) injury is unclear. In this study the roles of both iNOS and NO were characterized in a rat model of renal I/R injury. In addition, the effect of iNOS inhibition on renal function was evaluated. METHODS: Sprague-Dawley rats underwent 45 min of left renal ischemia and contralateral nephrectomy followed by various periods of reperfusion and renal function analysis [plasma creatinine, fractional excretion of sodium (FENa), creatinine clearance (CrCl), and measurement of plasma and urine NO levels]. In addition, the effect of treatment with 1400W, a highly selective iNOS inhibitor, was evaluated. RESULTS: Renal dysfunction peaked at 48 h after reperfusion and immunohistochemistry studies revealed iNOS expression in the vasculature (3 h) and renal tubules (48 h) after reperfusion. Renal function improved significantly in treated animals compared to controls [creatinine of 1.1 v. 1.9 mg/dl (P < 0.05) and CrCl of 0.54 v. 0.31 ml/min (P < 0.05), respectively]. In addition, FENa was decreased by 50%, plasma NO levels were significantly lower (32.7 v. 45.7 micromol/L, P < 0.01), and deposition of nitrotyosine in the tubules of treated rats was less than in control animals. CONCLUSIONS: These data support the hypothesis that iNOS and NO are involved in the pathogenesis of renal I/R injury and suggests that use of iNOS inhibitors may be a valuable therapeutic strategy clinical situations where renal I/R may be prevalent.     

Milrinone-induced postconditioning reduces hepatic ischemia-reperfusion injury in rats: the roles of phosphatidylinositol 3-kinase and nitric oxide

Background

Ischemic postconditioning (PostC) protects the liver against ischemia-reperfusion (IR) injury. Milrinone, a phosphodiesterase 3 inhibitor, has been reported to exhibit preconditioning properties against hepatic IR injury; however, its PostC properties remain unknown. This study investigated whether milrinone has PostC properties against hepatic IR injury and the roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS).

Materials and methods

Male Wistar rats were separated into six groups: (1) group S: animals that underwent sham operation without ischemia, (2) group C: ischemia followed by reperfusion with no other intervention, (3) group M: milrinone administered immediately after reperfusion, (4) group MW: wortmannin, a PI3K inhibitor, injected before milrinone administration, (5) group MN: l-NAME, a NOS inhibitor, injected before milrinone administration, and (6) group MD, milrinone administered 30 min after reperfusion. Except for group S, all groups underwent 1 h of warm ischemia of median and left lateral lobes, followed by 5 h of reperfusion. Biochemical liver function analysis and histologic examination were performed.

Results

Serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels, histologic damage scores, and apoptotic rate in group M were significantly lower than those in group C. The inhibition of PI3K or NOS prevented this protective effect. Milrinone administered 30 min after reperfusion did not show obvious protective effects.

Conclusions

Milrinone-induced PostC protects against hepatic IR injury when it is administered immediately after reperfusion, and PI3K and NOS may play an important role in this protective effect.     

诱导型一氧化氮合酶在舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤中的作用

目的 探讨诱导型一氧化氮合酶(iNOS)在舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤中的作用.方法 成年雄性SD大鼠30只,体重250～330 g,采用随机数字表法,将大鼠随机分为5组(n=6):假手术组(S组)只穿线,不结扎;心肌缺血再灌注组(I/R组)采用结扎左冠状动脉前降支30min,再灌注120 min的方法制备大鼠心肌缺血再灌注损伤模型;舒芬太尼预处理组(SF组)缺血前24 h经尾静脉输注舒芬太尼120μg/kg,输注时间30 min;舒芬太尼预处理+iNOS特异性抑制剂S-甲硫脲组(SF+SMT组)缺血前24 h经尾静脉输注舒芬太尼120μg/kg,缺血前10 min静脉注射SMT 10 mg/kg;SMT组缺血前10 min静脉注射SMT 10 mg/kg.于缺血前30 min、缺血30 min、再灌注120 min时记录HR和MAP,计算RPP(SP× HR).于再灌注120 min时取颈动脉血样2 ml,测定血浆NO浓度,随后取心脏制病理切片,测定缺血危险区(AAR)和梗死区(IS)体积,计算心肌梗死体积(IS/AAR),测定心肌iNOS表达.结果 与S组比较,余4组再灌注120 min时MAP和RPP降低,IS/AAR升高,I/R组和SMT组缺血30 min时MAP和RPP降低(P＜0.05);与I/R组比较,SF组、SF+SMT组和SMT组HR、MAP和RPP差异无统计学意义,SF+SMT组和SMT组IS/AAR和血浆NO浓度差异无统计学意义(P＞0.05),SF组IS/AAR降低,血浆NO浓度和心肌iNOS表达升高(P＜0.05).结论 iNOS参与了舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤的过程.

Abstract：

Objective To investigate the role of inducible nitric oxide synthase (iNOS) in reduction of myocardial ischemia-reperfusion (I/R) injury by sufentanil preconditioning in rats. Methods Thirty adult male SD rats, weighing 250-330 g, were randomly divided into 5 groups ( n =6 each): sham operation group (group S),I/R group, sufentanil preconditioning group (group SF), sufentanil preconditioning + a specific inhibitor of iNOS S-methyl thiourea (SMT) group (group SF+ SMT) and S-methyl thiourea group (group SMT). In I/R,SF,SF+SMT and SMT groups, myocardial I/R was produced by occlusion of left anterior descending coronary artery for 30 min followed by 120 min reperfusion. Group SF received 30 min infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia. Group SF + SMT received infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia and then SMT 10 mg/kg was injected 10 min before ischemia. In group SMT, SMT 10 mg/kg was injected 10min before ischemia. MAP and HR were recorded at 30 min before ischemia, at 30 min of ischemia and at the end of reperfusion. The rate-pressure product (RPP) was calculated. Arterial blood samples were obtained immediately at the end of reperfusion to determine the plasma concentration of NO. Then the animals were sacrificed and myo cardial tissues were obtained to determine the area at risk (AAR), infarct size (IS) and iNOS expression. IS/AAR was calculated. Results Compared with group S, MAP and RPP were significantly decreased, while IS/AAR was significantly increased at 120 min of reperfusion in the other four groups, and MAP and RPP were significantly decreased at 30 min of ischemia in I/R and SMT groups ( P ＜ 0.05). Compared with group I/R, no significant change was found in HR, MAP and RPP in SF, SF + SMT and SMT groups, and in IS/AAR and plasma NO concentrations in SF + SMT and SMT groups ( P ＞ 0.05), but IS/AAR was significantly decreased, and the plasma NO concentration and iNOS expression were significantly increased in group SF ( P ＜ 0. 05). Conclusion iNOS is involved in reduction of myocardial I/R injury by sufentanil preconditioning in rats.