糖尿病大鼠离体心脏对缺血/再灌注的耐受性

目的评价糖尿病大鼠离体心脏缺血／再灌注后心脏功能的改变。方法链佐星(60mg／kg)诱导的糖尿病大鼠16只(D组),年龄匹配的健康雄性SD大鼠10只(C组),戊巴比妥钠(60mg／kg)麻醉后快速取出心脏,接上主动脉插管置于Langendorg装置上,Krebs-Henseleit缓冲液逆行灌注。平衡灌注20min,待心率(HR)及冠脉流量平稳后夹闭灌注道,进行全心缺血30min,复灌40min。持续监测心肌心电活动、左心室压峰值(LVPSP)、左室舒张末压(LVEDP)和左室压力最大上升／下降速率(±dp／dtmax),计算左室发展压(LVDP=LVPSP-LVEDP),用LVDP×HR(RDPP)表示左室作功。结果与C组相比,基础状态下,D组大鼠心脏HR减慢,LVDP、RDPP和±dp／dtmax降低,LVEDP升高(P<0.05或0.01);再灌注后HR、LVDP、RDPP、冠脉流出液、±dp／dtmax等心功能指标恢复百分率升高,肌酸激酶活性降低(P<0.05或0.01);心脏缺血-停搏时间延长。结论糖尿病心脏基础心功能损伤严重,但对缺血／再灌注的耐受性增强。     

Gpx1-Klk1转基因对肾缺血再灌注损伤保护作用的研究

目的 制备人谷胱甘肽过氧化物酶（Gpx1）、 组织激肽释放酶（Klk1）共转基因小鼠,在此基础上制作肾缺血再灌注损伤小鼠模型。观察转基因小鼠对缺血再灌注损伤的耐受能力。在体研究Gpx1-Klk1转基因对肾缺血再灌注的保护作用。 方法 应用基因工程技术制备pKsp-Gpx1-IRES-Klk1质粒,酶切后回收转基因片段并纯化,通过外源基因受精卵雄原核显微注射法制备Gpx1-Klk1共转基因小鼠。采用丝线悬吊控制法制备转基因小鼠肾缺血再灌注模型。设立C57BL野生型小鼠同法制备的肾缺血再灌注损伤为对照。在肾缺血再灌注实验前后,测定血尿素氮、血肌酐、肾组织中超氧化物歧化酶（SOD）、丙二醛（MDA）、总一氧化氮合酶（tNOS）及诱导型一氧化氮合酶（iNOS）。留取肾脏组织制备病理切片,观察Gpx1-Klk1转基因小鼠抗肾缺血再灌注损伤的能力。 结果 获得全长为6.585 kb的pKsp-Gpx1-IRES-Klk1重组质粒,并证明了该克隆的正确性。在转基因小鼠制备过程中,共获得525枚注射卵,移植成功率为81.0%,小鼠出生总数109只。经基因组DNA的PCR检测,确认10只为转基因阳性小鼠,阳性率为9.2%。Western印迹法检测证实了阳性转基因小鼠肾脏组织有Gpx1和Klk1蛋白强表达。转基因小鼠（实验组）和野生型小鼠（对照组）肾缺血再灌注损伤模型建立后,实验组血样中尿素氮及肌酐水平显著低于对照组（P < 0.01）;肾脏组织中SOD显著高于对照组 （P < 0.01）,MDA显著低于对照组（P < 0.01）;两组肾组织中tNOS较缺血再灌注前均显著升高,且实验组显著高于对照组（P = 0.025）,实验组肾组织中iNOS显著低于对照组（P < 0.01）。缺血再灌注后,实验组肾组织间质轻度水肿,肾小管上皮坏死细胞较少,对标本损伤程度采用半定量评分后显示,实验组损伤程度显著轻于对照组（1.58±1.05比3.95±0.80,P < 0.05）。 结论成功制备Gpx1-Klk1转基因小鼠。Gpx1-Klk1过表达对肾缺血再灌注损伤的保护作用。     

Absence of heme oxygenase-1 exacerbates myocardial ischemia/reperfusion injury in diabetic mice

Increased production of reactive oxygen species contributes to the etiology of diabetes complications. Pathophysiological stimuli that increase oxidative stress upregulate heme oxygenase (HO)-1, a cytoprotective heme-degrading enzyme. We hypothesized that HO-1 may be important in myocardial injury that is exacerbated by diabetes. To test this hypothesis, the left anterior descending coronary arteries of nondiabetic and diabetic wild-type (HO-1(+/+)) and HO-1 null (HO-1(-/-)) mice were ligated for 1 h followed by 24 h reperfusion. The absence of HO-1 significantly increased myocardial infarct size (36.4 +/- 2.0 vs. 21.4 +/- 1.8% in HO-1(+/+) mice), while cardiac-specific overexpression of HO-1 protected against myocardial ischemic injury in diabetic mice. Despite similar high blood glucose levels, diabetic HO-1(-/-) mice had fourfold higher oxidative stress and larger infarcts (56.0 +/- 2.8%) than diabetic HO-1(+/+) mice (30.8 +/- 6.1%). Moreover, hyperglycemia increased the mortality of HO-1(-/-) mice (31.3%) after ischemia/reperfusion injury, and 55% of diabetic HO-1(-/-) mice had mural thrombi in the left ventricles. The increased mortality of diabetic HO-1(-/-) mice may be in part due to formation of left ventricular mural thrombi. Our data demonstrate that the absence of HO-1 renders animals more susceptible to myocardial ischemia/reperfusion damage and diabetes worsens the injury.     

Hepatic ischemia/reperfusion injury in P-selectin and intercellular adhesion molecule-1 double-mutant mice

Neutrophil adhesion and recruitment represents one of the early cellular events that occur during hepatic ischemia/reperfusion (IR) injury and plays a critical role in determining the extent of tissue damage. The adhesion molecules, such as selectins and intercellular adhesion molecules (ICAM), are important in mediating neutrophil-endothelial cell interactions and neutrophil emigration. The goal of this study was to evaluate the role of P-selectin and ICAM-1 in hepatic IR injury. Male wild-type and P-selectin/ICAM-1-deficient (P/I null) mice underwent 90 minutes of partial hepatic ischemia followed by reperfusion at various time points (0, 1.5, 3, and 6 hours). Reperfusion caused a time-dependent hepatocellular injury in both wild-type and P/I null mice as judged by plasma alanine aminotransferase (ALT) levels and liver histopathology examination. Although ALT levels were slightly lower in the P/I null mice compared with the wild-type mice the differences were not statistically significant. Neutrophil infiltration to the ischemic liver was observed in both mouse groups after 6 hours of reperfusion; however, the infiltration to the midzonal region of the ischemic liver was more pronounced in the wild-type group. This study suggests that hepatocellular injury induced after hepatic IR was independent of P-selectin and ICAM-1 in this model of acute inflammatory tissue injury.     

Bax ablation protects against hepatic ischemia/reperfusion injury in transgenic mice.

Apoptosis appears to be a central mechanism of cell death following reperfusion of the ischemic liver. The aim of this study was to determine the effect of decreased expression of the proapoptotic Bax gene on hepatic apoptotic warm ischemia/reperfusion (I/R) injury. Three groups of mice were studied: homozygotic knockout mice (Bax-/-); heterozygotic (Bax+/-); and wild type (Bax+/+). Isolated mouse livers were subjected to 90 minutes of ischemia (37 degrees C) followed by 15 minutes of reperfusion. Bax and Bcl-2 expression in liver tissue homogenates was measured by Western blot. Serum liver enzyme levels were measured and intrahepatic caspase-3 activity was determined by fluorimetric assay. Oil red O (ORO) staining was performed for fat detection. Apoptotic cells were identified by morphological criteria, immunohistochemistry for caspase-3, and terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling (TUNEL) assay. At 1 minute of reperfusion, the ischemic (Bax-/-) livers were characterized by statistically significantly lower liver enzyme levels and lower caspase-3 activity than the ischemic (Bax+/+) livers (P<0.05 for both). The reduction in postischemic apoptotic hepatic injury in the ischemic Bax-/- livers group was confirmed morphologically, by the significantly reduced microvesicular steatosis as determined by ORO staining, fewer apoptotic hepatocyte cells detected (P<0.05); immunohistochemically, by the significantly weaker activation of caspase-3 compared to the ischemic group (P<0.05); and by TUNEL assay (P<0.05). Similar levels of antiapoptotic Bcl-2 protein expression were detected in all 3 groups of ischemic livers on Western blots. Bax protein was not expressed in Bax-deficient livers and was detected in Bax+/+ normal livers. In the Bax+/- livers, levels of the damage markers were moderate. In conclusion, The better tolerance of Bax knockout livers to I/R injury suggests that the Bax gene may serve as a potential target for therapeutic intervention in hepatic I/R injury.     

Suramin promotes recovery from renal ischemia/reperfusion injury in mice

Suramin is a polysulfonated naphthylurea originally designed as a treatment for trypanosomiasis; but that has also been used to treat rodent models of fulminant hepatic failure and focal brain ischemia. In this study, we determined the effects of suramin on renal ischemia/reperfusion-induced acute kidney injury in mice, in particular its effect when administered after renal injury has been established. Increasing concentrations of suramin were given 24 hours following reperfusion, a time when serum creatinine levels were at their highest level. This treatment improved renal function, as evidenced by decreased blood urea nitrogen and serum creatinine to control values and diminished histopathologic tubular damage. Suramin-treated animals had a significant reduction in apoptotic tubular cells and infiltrating leukocytes. There was also an increase of proliferating tubular cells following reperfusion compared to the number found in untreated animals. Our study shows that suramin promotes the recovery of renal function and has effective therapeutic applications when given after the occurrence of renal injury.     

缺血再灌注损伤后小鼠肾脏血管内皮生长因子C的表达

目的探讨小鼠肾缺血再灌注损伤模型中血管内皮生长因子C的表达变化及其意义。方法建立小鼠肾缺血再灌注损伤模型。雄性C57BL／6小鼠用无创性动脉夹夹闭左肾动脉,置于32℃温箱后1h松开血管夹,取出右肾。Sham组操作同上,但不夹闭左肾动脉。再灌注0,6,12,24,48h后处死小鼠,收集外周血及肾脏标本。测定血肌酐（SCr）和尿素氮（BUN）水平。HE染色观察Sham组和缺血再灌注24h组（IR24h组）肾脏病理学变化,免疫组织化学检测Sham组和IR24h组血管内皮生长因子C（vascularendothelialgrowthfactorC,VEGF-C）在肾脏的表达及分布,连续切片检测VEGF-C与其受体血管内皮生长因子受体3（VEGFR-3）的共定位。Westernblot检测缺血后不同灌注时间VEGF-C的表达变化。结果小鼠肾脏缺血再灌注损伤后,SCr和BUN水平上升,且随着再灌注时间的延长肾功能损伤逐渐加重,再灌注24h时肾功能损伤最明显,再灌注48h时肾功能已经有部分恢复。与Sham组比较,缺血再灌注24h肾脏组织肾小管管腔扩张,内有管型形成,肾小管上皮细胞肿胀坏死,空泡变性,刷状缘坏死脱落,并且伴有炎性细胞侵润,而肾小球未见明显病变。免疫组织化学结果显示,与Sham组比较,缺血再灌注24h肾脏VEGF-C及其受体VEGFR-3的表达均明显增加,二者存在着共定位现象,且主要表达在肾脏皮髓质交界处及髓质部的肾小管。Westernblot结果显示随着缺血后再灌注时间的延长,VEGF-C的表达增加。结论肾缺血再灌注损伤后存在肾脏VEGF-C的表达上升,且与其受体VEGFR-3的表达增加呈共定位,推测VEGF-C可能参与了肾脏缺血再灌注损伤。     

Local and remote ischemia-reperfusion injury is mitigated in mice overexpressing human C1 inhibitor

Activation of the classical complement pathway is crucially involved in complement-mediated endothelial cell damage in ischemia-reperfusion injury. C1 inhibitor is the only known physiological inhibitor of classical complement pathway activation. Transgenic mice overexpressing human C1 inhibitor were used in a surgical lower torso and a liver ischemia-reperfusion model. Organ-specific endothelial disruption was determined by 125I-tagged albumin extravasation. In the lower torso ischemia-reperfusion model, transgenic mice overexpressing the C1 inhibitor were protected in the muscle and the lungs from endothelial cell damage. In the liver ischemia-reperfusion model, endothelial cell integrity was preserved in transgenic animals in the liver, the gut and the lungs. Our data indicate that inhibiting complement activation by a transgenic approach is effective in protection against ischemia-reperfusion injury.     

Overexpression of stanniocalcin-1 inhibits reactive oxygen species and renal ischemia/reperfusion injury in mice

Reactive oxygen species, endothelial dysfunction, inflammation, and mitogen-activated protein kinases have important roles in the pathogenesis of ischemia/reperfusion kidney injury. Stanniocalcin-1 (STC1) suppresses superoxide generation in many systems through the induction of mitochondrial uncoupling proteins and blocks the cytokine-induced rise in endothelial permeability. Here we tested whether transgenic overexpression of STC1 protects from bilateral ischemia/reperfusion kidney injury. This injury in wild-type mice caused a halving of the creatinine clearance; severe tubular vacuolization and cast formation; increased infiltration of macrophages and T cells; higher vascular permeability; greater production of superoxide and hydrogen peroxide; and higher ratio of activated extracellular regulated kinase/activated Jun-N-terminal kinase and p38, all compared to sham-treated controls. Mice transgenic for human STC1 expression, however, had resistance to equivalent ischemia/reperfusion injury indicated as no significant change from controls in any of these parameters. Tubular epithelial cells in transgenic mice expressed higher mitochondrial uncoupling protein 2 and lower superoxide generation. Pre-treatment of transgenic mice with paraquat, a generator of reactive oxygen species, before injury restored the susceptibility to ischemia/reperfusion kidney injury, suggesting that STC1 protects by an anti-oxidant mechanism. Thus, STC1 may be a therapeutic target for ischemia/reperfusion kidney injury.     

The role of HMGB-1 on the development of necrosis during hepatic ischemia and hepatic ischemia/reperfusion injury in mice

BACKGROUND: High-mobility group 1 (HMGB-1) is a late mediator of endotoxin lethality in mice. The release of HMGB-1 is delayed compared to other proinflammatory cytokines that mediate shock and tissue injury. The purpose of this study was to investigate the role of HMGB-1 levels in response to hepatic ischemia, hepatic I/R injury, and the relationship between changes in HMGB-1 and other cytokines. MATERIALS AND METHODS: Three murine models were employed: our robust model of segmental hepatic warm ischemia (SHWI), a model of partial hepatic ischemia/reperfusion injury (PHIRI), and a model of total hepatic ischemia/reperfusion injury (THIRI). Over a 48-h period following ischemic insult and reperfusion using these models, serum HMGB-1 concentrations, concentrations of HMGB-1 in ischemic and nonischemic lobes, and serum concentrations of TNF-alpha and IL-6 levels were determined in mice. An anti-HMGB-1 antibody treatment was used in SHWI and THIRI to evaluate what aspects of response to ischemia and reperfusion were potentially mediated by HMGB-1. RESULTS: Hepatic HMGB-1 tissue concentrations exhibited biphasic changes in SHWI mice, which were increased in the ischemic lobes relative to nonischemic lobes at 12 h but decreased relative to nonischemic lobes at 24 h after ischemic insult. These results suggested that HMGB-1 was released into the systemic circulation by necrotic cells over the first 12 h but this process may be complete by 24 h postischemia. By 6 to 12 h after SHWI, serum TNF-alpha began to increase significantly and continued to increase for 18 h, followed by a sudden decline. Similarly, serum IL-6 increased over 1-3 h after SHWI and then decreased over the next 6 h. Treatment with an anti-HMGB-1 antibody significantly prolonged survival time in SHWI and THIRI. CONCLUSIONS: HMGB-1 plays a significant role in the response to hepatic ischemia and hepatic ischemia/reperfusion injury. The present study demonstrated a time-dependent production of HMGB-1 following hepatic warm ischemia in mice. The inherent HMGB-1 in ischemic areas was exhausted and HMGB-1 may be released by necrotic cells. HMGB-1 activation is involved in immediate proinflammatory stress response to I/R and anti-HMGB-1 antibody treatment remarkably improved survival. We demonstrated that systemic HMGB-1 accumulation was measured at an earlier phase of the hepatic ischemia and ischemia/reperfusion injury model than LPS-induced endotoxemia.     

Calpain inhibitor-1 reduces renal ischemia/reperfusion injury in the rat

BACKGROUND: Activation of the cysteine protease calpain has been implicated in renal ischemia/reperfusion (I/R) injury. The aim of this study was to investigate the effects of calpain inhibitor-1 (Cal I-1) in an in vivo model of renal I/R injury. METHODS: Male Wistar rats were administered Cal I-1 (10 mg/kg, IP) 30 minutes before undergoing bilateral renal ischemia (45 minutes) followed by reperfusion (6 hours). Plasma concentrations of urea, creatinine, Na(+), gamma-glutamyl transferase (gamma GT), aspartate aminotransferase (AST) and urinary Na(+), glutathione S-transferase (GST), and N-acetyl-beta-D-glucosaminidase (NAG) were measured for the assessment of renal dysfunction and I/R injury. Creatinine clearance (C(Cr)) and fractional excretion of Na(+) (FE(Na)) were used as indicators of glomerular and tubular function, respectively. Kidney myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were measured for assessment of neutrophil infiltration and lipid peroxidation, respectively. Renal sections were used for histologic grading of renal injury and for immunohistochemical localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). RESULTS: Cal I-1 significantly reduced I/R-mediated increases in urea, creatinine, gamma GT, AST, NAG, and FE(Na) and significantly improved C(Cr). Cal I-1 also significantly reduced kidney MPO activity and MDA levels. Cal I-1 also reduced histologic evidence of I/R-mediated renal damage and caused a substantial reduction in the expression of iNOS and COX-2, both of which involve activation of nuclear factor-kappa B (NF-kappa B). CONCLUSIONS:: These results suggest that Cal I-1 reduces the renal dysfunction and injury associated with I/R of the kidney. We suggest that the mechanism could involve the inhibition of I/R-mediated activation of NF-kappa B.     

甘露醇对脑缺血/再灌注损伤后干预效果评价的实验研究

目的 探索脑缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)后甘露醇干预的最佳时机.方法 健康昆明小鼠36只,制备I/RI模型后,按随机数字表法分为6组(每组6只):假手术组(A组)、对照组即I/RI组(B组)和再灌注即刻、30 min、1、1.5 h甘露醇干预组(分别为C、D、E和...     

静脉注射含饱和氢气生理盐水减轻小鼠肾脏缺血再灌注损伤

目的 研究静脉注射含饱和氢气生理盐水对小鼠肾脏缺血再灌注(IR)损伤的保护作用及其机制.方法 健康、雄性的C57BL/6小鼠随机分为3组,每组10只.假手术组(SO组)小鼠仅接受中线开腹、双侧肾蒂游离及关腹操作;缺血再灌注组(IR组)小鼠用无损伤动脉夹同时钳夹双侧肾蒂,阻断45 min,制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射生理盐水,5 ml/kg;实验组小鼠制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射含饱和氢气生理盐水,5 ml/kg.各组小鼠于肾脏再灌注6 h时检测血清尿素氮(BUN)和肌酐(Scr);检测肾组织中丙二醛(MDA)和髓过氧化物酶(MPO)的含量;观察肾脏组织形态学变化并检测肾小管上皮细胞的凋亡情况;观察肾组织中巨噬细胞的浸润情况;检测各组小鼠肾组织中肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、IL-1β和IL-17 mRNA的水平.结果 实验组血清BUN和Scr水平明显低于IR组(P<0.05).实验组肾组织病理改变较IR组明显减轻,其肾小管损伤评分明显低于IR组(P<0.01),肾小管上皮细胞凋亡明显轻于IR组(P<0.05).实验组肾组织内MDA含量低于IR组(P<0.05).实验组小鼠肾组织内中性粒细胞和巨噬细胞的浸润较IR组减少(P<0.05).实验组TNF-α、IL-6、IL-1β和IL-17mRNA的水平均低于IR组(P<0.05).结论 静脉注射含饱和氢气生理盐水能够在一定程度上减轻肾脏IR损伤,其机制可能与抑制肾脏IR后炎症反应有关.     

Human C1 esterase inhibitor attenuates murine mesenteric ischemia/reperfusion induced local organ injury

BACKGROUND: Complement activation contributes to ischemia and reperfusion (IR)-initiated organ injury. C1 inhibitor (C1 Inh) inhibits the earliest steps of the classical and the mannose binding lectin pathways. MATERIALS AND METHODS: To determine whether C1 Inh prevented tissue injury, we performed intestinal IR experiments in BALB/c and C57BL/6 mice. RESULTS: We found that C1 Inh limits mucosal injury in the two strains in a dose dependent manner. Tissue damage was associated with the accumulation of functional polymorphonuclear cells, which was reduced following C1 Inh treatment. Constitutive nitric oxide synthase activity correlated with the development of injury in the C57BL/6 but not in the BALB/c mouse. CONCLUSIONS: These findings emphasize the importance of complement activation in ischemia/reperfusion and highlight the potential therapeutic use of C1 Inh in limiting or preventing damage caused by IR.     

胆总管结扎预适应减轻小鼠肾脏缺血再灌注损伤

目的 探讨胆总管结扎预适应减轻小鼠肾脏缺血再灌注损伤的可能机制.方法 C57BL/6小鼠分为3组进行实验.胆总管结扎预适应组(CBDL组)结扎胆总管(d0),2d后(d2)再通,再过2d后(d4)行左肾缺血再灌注手术;假手术组仅结扎胆囊管(d0),d4再行左肾缺血再灌注手术;对照组不进行任何处理.监测血胆红素总量(TBil)的变化情况.肾脏缺脏再灌注后24 h(dS)检测各组小鼠血清肌酐(Cr).蛋白质印迹法检测CBDL组和假手术组肾脏热休克蛋白27 (HSP-27)和内皮型一氧化氮合酶(eNOS)的表达情况.结果 CBDL组胆总管结扎2d后,TBil达到最高,再通2d后,TBil基本降至正常水平.CBDL组Cr低于假手术组(P＜0.05).CBDL组HSP-27和eNOS的表达量高于假手术组(P＜0.05).结论 胆道结扎预适应能明显减轻小鼠肾脏缺血再灌注损伤,其机制可能与引起肾脏局部HSP-27和eNOS高表达有关.     

低氧诱导因子1α高表达对小鼠急性缺血性肾损伤的影响

目的 探讨低氧预处理诱导低氧诱导因子1α（HIF-1α）高表达对小鼠肾缺血再灌注损伤（IRI）的影响及其可能机制。 方法 雄性C57BL/6N小鼠35只，随机分为健康对照组、氯化钴（CoCl2）组和8%O2组，每组10只；预处理12 h后，以上3组各取5只，分为缺血再灌注（IR）组、CoCl2＋IR组、8%O2＋IR组；另设5只作为假手术对照组。采用夹闭双侧肾蒂30 min的方法建立肾缺血动物模型，观察CoCl2和8％O2预处理对小鼠IR 24 h后肾功能、肾组织病理和相关肾损伤指标的影响及与CoCl2和8％O2诱导HIF-1α及其保护性靶基因血红素氧化酶1（HO-1）表达之间的关系。 结果 CoCl2＋IR组小鼠的肾功能[BUN (35.2±12.2) mmol/L，Scr (34.0±9.7) μmol/L]和8%O2＋IR组小鼠的肾功能[BUN (31.8±9.1) mmol/L，Scr (41.6±10.6) μmol/L]均较IR组[BUN (65.8±2.6) mmol/L，Scr (229.5±11.2) μmol/L]显著改善（P < 0.01）；与此相一致，CoCl2＋IR组和8%O2＋IR组的病理学改变、细胞凋亡程度和波形蛋白的表达均明显低于IR组。另外，CoCl2组和8%O2组中HIF-1α及其靶基因HO-1的表达明显高于健康对照组。 结论 低氧预处理可上调体内HIF-1α表达，对小鼠IRI肾脏具有良好保护效果     

Hepatocellular ultrastructure after ischemia/reperfusion injury in human orthotopic liver transplantation

The number of patients requiring organ transplants still outpaces the number of available transplantable organs. During the process of orthotopic liver transplantation (OLTx), donor organs undergo significant stress resulting from ischemia and reperfusion. Healthy organs respond to this stressful environment with compensatory mechanisms that ideally allow for complete recovery. However, "marginal" organs do not compensate as well. Hepatic steatosis typically renders an organ nontransplantable; a liver with 30% or more fat has a 25% chance of primary nonfunction (PNF) or graft failure after a technically sound operation. In this study, we report on the significant markers of cellular ultrastructural change in steatotic livers. These include glycogen content, mitochondrial swelling, and hepatocellular blebbing. The data disclosed here argue that further investigation of these factors in marginal organs subjected to I/R may better facilitate our understanding of PNF.