Anti-lipid peroxidation and protection of liver mitochondria against injuries by picroside Ⅱ

AIM: To investigate the anti-lipid peroxidation and protection of liver mitochondria against injuries in mice with liverdamage by picroside Ⅱ.METHODS: Three animal models of liver damageinduced by carbon tetrachloride (CCl4:0.1 mL/10 g, ip),D-galactosamine (D-GalN: 500 mg/kg,ip) and acetaminophen (AP: 0.15 g/kg, ip) were respectively treated with various concentrations of picroside Ⅱ (5, 10, 20 mg/kg, ig). Then we chose the continuously monitoring method (recommended by International Clinical Chemistry League) to analyze serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values, Marland method to detect the activity of manganese-superoxide dismutase (SOD) in liver mitochondria, TBA colorimetry to determine the content of malonicdialdehyde (MDA) in liver tissue, DTNB method to evaluate the activity of glutathioneperoxidase (GSH-Px) and Lowry method to detect protein level in liver tissue. Meanwhile, effects of picroside Ⅱ on the activity of ATPase and swelling extent of mitochondria in hepatocytes damaged by AP were also evaluated.RESULTS: Picroside Ⅱ could significantly prevent liver toxicity in the three models of liver damage. It decreased the high levels of ALT and AST in serum induced by theadministration of CCl4, D-GalN and AP, reduced the cellular damage of liver markedly, and appeared to be even more potent than the positive control drug of biphenyl dimethyl dicarboxylate pilules (DDB). In groups treated with different doses of picroside Ⅱ, compared to the model group, the content of MDA in serum decreased evidently, whereas the content of SOD and GSH-Px increased in a dosedependent manner, and the difference was statistically significant. Further, in the study of AP model, picroside Ⅱinhibited AP-induced liver toxicity in mice, enhanced the activity of ATPase, improved the swelling extent of mitochondria and helped to maintain a normal balance of energy metabolism.CONCLUSION: Picroside Ⅱ can evidently relieve hepatocyteinjuries induced by CCl4, D-GalN and AP, help scavenge free radicals, protect normal constructions of mitochondria membrane and enhance the activity of ATPase in mitochondria,thereby modulating the balance of liver energy metabolism, which might be part of the mechanisms of hepatoprotectiveeffects of picroside Ⅱ.

Proteomic analysis of glutathione S-transferase isoforms in mouse liver mitochondria

AIM:To survey glutathione(GSH) S-transferase(GST) isoforms in mitochondria and to reveal the isoforms' biological significance in diabetic mice.METHODS:The presence of GSTs in mouse liver mitochondria was systematically screened by two proteomic approaches,namely,GSH affinity chromatography/two dimensional electrophoresis(2DE/MALDI TOF/TOF MS) and SDS-PAGE/LC ESI MS/MS.The proteomic results were further confirmed by Western blotting using monoclonal antibodies against GSTs.To evaluate the liver mitochondrial GSTs quantitatively,calibration curves were generated by the loading amounts of individual recombinant GST protein vs the relative intensities elicited from the Western blotting.An extensive comparison of the liver mitochondrial GSTs was conducted between normal and db/db diabetic mice.Student's t test was adopted for the estimation of regression and significant difference.RESULTS:Using GSH affinity/2DE/MALDI TOF/TOF MS,three GSTs,namely,alpha3,mu1 and pi1,were identified;whereas five GSTs,alpha3,mu1,pi1,kappa1 and zeta1,were detected in mouse liver mitochondria using SDS-PAGE/LC ESI MS/MS,of these GSTs,GST kappa1 was reported as a specific mitochondrial GST.The R 2 values of regression ranged between values of about 0.86 and 0.98,which were acceptable for the quantification.Based on the measurement of the GST abundances in liver mitochondria of normal and diabetic mice,the four GSTs,alpha3,kappa1,mu1 and zeta1,were found to be almost comparable between the two sets of animals,whereas,lower GST pi1 was detected in the diabetic mice compared with normal ones,the signal of Western blotting in control and db/db diabetic mice liver mitochondria is 134.61 ± 53.84 vs 99.74 ± 46.2,with P < 0.05.CONCLUSION:Our results indicate that GSTs exist widely in mitochondria and its abundances of mitochondrial GSTs might be tissue-dependent and disease-related.

Dexamethasone treatment alters kinetics properties of liver mitochondrial F₀.F₁-ATPase and membrane lipid profiles in developing and adult rats

Dexamethasone—a potent synthetic glucocorticoid—has multiple diagnostic and therapeutic applications in wide range of age groups. However, the side-effects of dexamethasone (Dex) treatment including those on development are becoming increasingly apparent. Since the developmental processes are energy-dependent, we examined the effects of chronic Dex treatment on kinetics properties of liver mitochondrial F0.F1-ATPase and mitochondrial membrane lipid profiles in rats belonging to different developmental age groups (2, 3, 4 and 5 weeks) and in adults (~8 weeks). The animals were treated with a subcutaneous dose of 2 mg of Dex/kg body weight (or saline as vehicle) for three alternative days (at around 7.00 A.M.) prior to the day of sacrifice. Dex treatment resulted in significant reduction in F0.F1-ATPase activity in developmental age groups and in adults as compared to their age-matched vehicle-treated control group. The substrate kinetics analysis of F0.F1-ATPase resolved Km and Vmax values in 3 components in all the control age groups;whereas Dex treatment significantly altered the Km and Vmax values or abolished the entire components in age-specific manner. Dex treatment significantly lowered the energy of activation and altered phase transition temperature (TtoC) in all the developmental age groups and in adults. Dex treatment significantly increased the contents of total phospholipid (TPL), individual phospholipids classes and cholesterol (CHL) in all the developmental age groups whereas opposite pattern was observed in adults. The mitochondrial membrane became more fluidized in the developing age groups (2, 4 and 5 weeks);whereas no change was observed in 3-week and adult groups following Dex treatment. In present study, our data demonstrate comprehensive deleterious effects of chronic Dex treatment on liver mitochondrial membrane structure and F0.F1-ATPase functional properties with respect to energy metabolism. At the same time, our data also warns against excessive repeated use of antenatal DEX in treatments in growing and adult human patients.

A study on liver mitochondria respiration and protein synthesis in cold adapted rats

Mitochondria were isolated from normal and cold adapted rat livers.The respiratory func-tion of mitochondria in rat livers,including ADP:O ratio(P/O)and the respiratory control ratio(RCR),was determined by oxygen electrode method,The protein synthesis in mitochondria wasstudied by observing the incorporation of[~3H]-Leucine into mitochondria.Polyacrylamide gelelectrophoresis was carried out to detect the changes of the inner membrane proteins.It was shownthat the P/O and RCR decreased in cold adapted rats in the 2nd and 4th weeks and returned tothe control level in the 6th week,the protein synthesis of mitochondria decreased significantly incold adapted rats in 1,2 and 4 weeks;the electrophoretic pattern of the inner membrane proteinsin mitochondria from cold adapted rat livers revealed some new bands.

Effect of Copper Sources and Levels on Hydrogen Peroxide Generation by Mitochondria from Broiler Liver

The present experiment was performed with the objective of examining the effects of copper sources and levels on hydrogen peroxide(H_2O_2) generation by mitochondria from broiler hepatocytes. Treatments were applied to compare sources of copper(CuSO_4 versus Cu-Met) and 4 levels of dietary Cu (11,110,220 and 330 mg/kg).Day-old broilers(Cobb 500,Gallus domesticus,n=288) were randomly divided into 8 groups of 36 each and fed diets as follows:Controls(Cu 11 mg/kg) and high copper(Cu 110, 220,and 330 mg/kg),for 60 days under normal conditions.Sample collections were made at 12,36 and 60 days of age to investigate the changes in H_2O_2 generation by mitochondria from hepatocytes.Compared with those of the control diets,H_2O_2 generation by mitochondria in the high copper groups(110 to 330 mg/kg) of the two copper sources were increased(P<0.05 or P<0.01);At days 36 and 60,H_2O_2 generation by hepatic mitochondria from Cu-Met supplementation exceeded that from birds supplemented with CuSO_4 (P<0.05 or P<0.01).In addition,H_2O_2 generation by mitochondria from broilers fed with high dietary copper appeared to be associated with altered function of mitochondrial complexⅣ.The results indicated that dietary supplementation with copper induced oxidative stress damage in liver.At each level of copper supplementation,the organic Cu-Met led to more rapid H_2O_2 generation than did inorganic CuSO_4.The results also suggest that mitochondrial complexⅣmay be targeted under conditions of high dietary copper supplementation.

Nonalcoholic fatty liver disease and mitochondrial dysfunction

Nonalcoholic fatty liver disease (NAFLD) includes hepatic steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. NAFLD is the most common liver disorder in the United States and worldwide. Due to the rapid rise of the metabolic syndrome, the prevalence of NAFLD has recently dramatically increased and will continue to increase. NAFLD has also the potential to progress to hepatocellular carcinoma (HCC) or liver failure. NAFLD is strongly linked to caloric overconsumption, physical inactivity, insulin resistance and genetic factors. Although significant progress in understanding the pathogenesis of NAFLD has been achieved in years, the primary metabolic abnormalities leading to lipid accumulation within hepatocytes has remained poorly understood. Mitochondria are critical metabolic organelles serving as "cellular power plants". Accumulating evidence indicate that hepatic mitochondrial dysfunction is crucial to the pathogenesis of NAFLD. This review is focused on the significant role of mitochondria in the development of NAFLD.

Role of mitochondria in alcoholic liver disease

Alcohol abuse is the leading cause of liver related morbidity and mortality.Chronic or binge alcohol drinking causes hepatic steatosis which can develop to steatohepatitis,cirrhosis and ultimately hepatocellular carcinoma.The pathogenesis of alcoholic liver disease(ALD)is poorly characterized,however several recent studies point to a major role of mitochondria in this process.Mitochondria play a crucial role in cellular energy metabolism and in reactive species formation.Alcohol treatment causes mitochondrial DNA damage,lipid accumulation and oxidative stress.Studies in both animal models and in humans showed that alcohol administration causes changes in the mitochondrial morphology and function suggesting a role of these changes in the pathogenesis of ALD.We review recent findings on mechanisms by which alcohol negatively impacts mitochondrial biogenesis and function and we will discuss the specific intracellular pathways affected by alcohol consumption.Interestingly,recent findings indicate that a large number of mitochondrial proteins are acetylated and that mitochondrial proteins acetylation and sirtuins are modulated by alcohol.Un-derstanding the mechanisms behind alcohol mediated impaired mitochondrial biogenesis and function may help identify potential therapeutic targets for treating ALD in humans.

Experimental research on phospholipids variation of halothane on liver mitochondria

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Novel interactions of mitochondria and reactive oxygen/nitrogen species in alcohol mediated liver disease

Mitochondrial dysfunction is known to be a contributing factor to a number of diseases including chronic alcohol induced liver injury. While there is a detailed understanding of the metabolic pathways and proteins of the liver mitochondrion, little is known regarding how changes in the mitochondrial proteome may contribute to the development of hepatic pathologies. Emerging evidence indicates that reactive oxygen and nitrogen species disrupt mitochondrial function through post-translational modifications to the mitochondrial proteome. Indeed, various new affinity labeling reagents are available to test the hypothesis that post-translational modification of proteins by reactive species contributes to mitochondrial dysfunction and alcoholic fatty liver disease. Specialized proteomic techniques are also now available, which allow for identification of defects in the assembly of multi-protein complexes in mitochondria and the resolution of the highly hydrophobic proteins of the inner membrane. In this review knowledge gained from the study of changes to the mitochondrial proteome in alcoholic hepatotoxicity will be described and placed into a mechanistic framework to increase understanding of the role of mitochondrial dysfunction in liver disease.

A study on mitochondrial respiratory dysfunction and lipid peroxidation in the liver after radiation,burn,and combined radiation-burn injuries in mice

Male mice were subjected to 6 Gy total body irradiation,20% TBSAfull-thickness burns,or combined radiation-burn injury and lipid peroxides(LPO),vita-min E,sulfhydryl group,respiratory control ratio(RCR),ADP/O ratio,and cytochromeoxidase activity of the liver mitochondria were determined in the first 9 d postinjury.Theresults are as follows:(1)LPO level increased in the early postinjury stage after combinedradiation-burn injury,on the 5th-7th day after irradiation and on the 7th day postburn.(2)Vitamin E level decreased significantly in the two groups of radiation and burn inju-ries but showed no significant decrease after combined injury.(3)The sulfhydryl groupshowed a tendency to increase in all the 3 groups.(4)The activity of cytochrome oxidaseincreased significantly on the 7th day after radiation but decreased considerably in theburn and combined injury groups.(5)RCR and ADP/O ratio decreased more significantlyin the combined injury group than in either the radiation group or the burn group.These facts suggest that the respiratory dysfunction of the liver mitochondria results mostprobably from the damage on the mitochondrial membrane due to lipid peroxidation.

Antigenically dominant proteins within the human liver mitochondrial proteome identified by monoclonal antibodies

Analysis of the mitochondrial proteome would provide valuable insight into the function of this important organelle, which plays key roles in energy metabolism, apoptosis, free radical production, thermogenesis, and calcium signaling. It could also increase our understanding about the mechanisms that promote mitochondrial disease. To identify proteins that are antigenically dominant in human liver mitochondria, we generated >240 hybridoma cell lines from native mitochondrial proteins after cell fusion, screening, and cloning. Antibodies that recognized mitochondrial proteins were identified by screening human liver cDNA expression libraries. In this study, we identified 6 major antigens that were recognized by at least 2 different monoclonal antibodies (mAbs). The proteins that were antigenically dominant were: acetyl-Coenzyme A acyltransferase 2 (mitochondrial 3-oxoacyl-Coenzyme A thiolase), aldehyde dehydrogenase 1 family member A1, carbamoyl phosphate synthetase 1, dihydrolipoamide S-acetyltransferase (E2 component of pyruvate dehydrogenase complex), enoyl coenzyme A hydratase 1, and hydroxysteroid (11-beta) dehydrogenase 1. We also determined the subcellular localizations of these enzymes within the mitochondria using immunohistocytochemistry. We believe that these well-characterized antibodies will provide a valuable resource for the Human Liver Proteome Project (HLPP), and will make studies aimed at investigating liver mitochondrial function far easier to perform in future. Our results provide strong evidence that, (i) depletion of dominant proteins from liver mitochondrial samples is possible and, (ii) the approaches adopted in this study can be used to explore or validate protein-protein interactions in this important organelle.

Mitochondrial metabolomic profiling for elucidating the alleviating potential of Polygonatum kingianum against high-fat diet-induced nonalcoholic fatty liver disease

BACKGROUND Developing mitochondrial regulators/nutrients from natural products to remedy mitochondrial dysfunction represent attractive strategies for therapy of nonalcoholic fatty liver disease(NAFLD).Polygonatum kingianum(PK)has been traditionally used in China as a medicinal and nutritional ingredient for centuries and can alleviate high-fat diet(HFD)-induced NAFLD by promoting mitochondrial functions.To date,the underlying molecular mechanism of PK for treating mitochondrial dysfunctions and thus alleviating NAFLD remains unclear.AIM To identify the molecular mechanism behind the mitochondrial regulatory action of PK against HFD-induced NAFLD in rats.METHODS NAFLD model was induced in rats with HFD.The rats were intragastrically administered PK(4 g/kg per day)for 14 wk.Metabolites in hepatic mitochondrial samples were profiled through ultra-high performance liquid chromatography/mass spectrometry followed by multivariate statistical analysis to find the potential biomarkers and metabolic pathways.RESULTS PK significantly restored the metabolites’levels in the mitochondrial samples.Ten potential biomarkers were identified in the analyzed samples.These biomarkers are involved in riboflavin metabolism.CONCLUSION PK can alleviate HFD-induced NAFLD by regulating the riboflavin metabolism and further improving the mitochondrial functions.Thus,PK is a promising mitochondrial regulator/nutrient for alleviating NAFLD-associated diseases.

肝线粒体功能障碍在非酒精性脂肪性肝病发病中的作用机制

非酒精性脂肪性肝病(NAFLD)逐渐成为影响人类肝脏健康的主要原因,其发生发展涉及多方面因素。线粒体作为细胞的“能量工厂”,对维持机体正常生理功能起着重要作用。研究表明,肝线粒体功能障碍促进NAFLD的发生发展。本文简要介绍了肝线粒体的基本特征和生理功能研究的新进展,综述了近年来线粒体功能障碍与肥胖、单纯性脂肪肝和非酒精性脂肪性肝炎关系研究方面的新成果,旨在为靶向线粒体治疗NAFLD提供研究思路。

Study on the Action of Sodium Selenite on the Mit ochondria Metabolism of Carassius auratus Hybrid Carps Liver by Microcalorimetry

By using an LKB\|2277 bioactivity monitor and a mpoule method, the fundamental thermogenesis curves of the metabolic process of liver mitochondria from Carassius auratus hybrid carps and the toxic effect of Na 2 SeO 3 on it were studied at 28 ℃.From the thermogenes is curves, the thermokinetic equations were established under different conditio n. The kinetics show that Na 2 SeO 3 has toxic action on the m etabolism process of Carassius auratus hybrid carps liver mitochondria.

AIFM2和MFN2与代谢相关脂肪性肝病患者胰岛素抵抗及进展性肝纤维化相关性的分析

目的探讨线粒体相关凋亡诱导因子2(AIFM2)和线粒体融合素2(MFN2)与代谢相关脂肪性肝病(MAFLD)患者胰岛素抵抗及进展性肝纤维化的相关性。方法选择2020年12月至2022年12月在如皋市人民医院就诊的120例MAFLD患者作为研究对象(设为观察组),另选择同期于该院体检的120名健康体检者纳入研究(设为对照组)。收集2组的一般资料,采集空腹静脉血,测定空腹血糖(FPG)、空腹胰岛素(FINS)、Ⅳ型胶原(CⅣ)、Ⅲ型前胶原(PCⅢ)、层粘连蛋白(LN)、透明质酸(HA)水平,以及血清AIFM2和MFN2表达水平。应用非酒精性脂肪性肝病纤维化评分(NFS)评估受试者的肝纤维化程度,将NFS≥0.676者纳入进展性肝纤维化组(n=31),将NFS<0.676者纳入非进展性肝纤维化组(n=89)。采用Pearson相关性分析探讨MAFLD患者的血清AIFM2和MFN2表达水平与胰岛素抵抗及肝纤维化指标的关系。采用多因素logistic回归模型分析MAFLD患者发生进展性肝纤维化的危险因素。结果与对照组相比,观察组的平均BMI和平均腰臀比(WHR)均较大,血清AIFM2和MFN2表达水平均较低,血清CⅣ、PCⅢ、LN和HA水平均较高,FPG、FINS水平及稳态模型胰岛素抵抗指数(HOMA-IR)均较高,差异均有统计学意义(P均<0.05)。Pearson相关性分析结果显示,MAFLD患者的血清AIFM2和MFN2表达水平均与HOMA-IR呈显著负相关(P均<0.05),血清AIFM2和MFN2表达水平均与血清CⅣ、PCⅢ、LN和HA水平呈显著负相关(P均<0.05)。进展性肝纤维化组的血清AIFM2和MFN2表达水平均显著低于非进展性肝纤维化组,差异均有统计学意义(P均<0.05)。多因素logistic回归模型分析结果显示,WHR、BMI、HOMA-IR、血清AIFM2和MFN2均是MAFLD患者发生进展性肝纤维化的独立危险因素(P均<0.05)。结论MAFLD患者的血清AIFM2和MFN2均呈低表达,且两者均与胰岛素抵抗和进展性肝纤维化密切相关,监测上述指标可为临床诊疗提供有效信息,对改善预后及预防并发症均具有重要意义。

Investigation of Interaction of Some Chalcones and Cyclic Chalcone Analogues with Outer Mitochondrial Membrane by UV-VIS and Fluorescence Spectroscopy

Interaction of the synthetic chalcones (1b,1c) and their cyclic analogues (2b,2c) with bovine (BSA) and human serum albumin (HSA) as well as with rat liver mitochondria (RLM) was studied by fluorescence spectroscopy. The maxima of emission fluorescence spectra were changed only in the case of 2b and 2c during interaction with BSA, HSA as well as mitochondrial outer membrane showing a slight hypsochromic shift and decrease of fluorescence. Interaction of the methoxy-(1b,2b) and the dimethylamino-substituted (1c,2c) compounds with outer mitochondrial membrane were studied by fluorescence polarization. Fluorescence polarization of 1b in the presence of the two proteins and mitochondria was found to be unchanged. Under similar conditions (2b,1c,2c) showed continuously increasing fluorescence polarization signal during the 30 minute period of investigations. Since fluorescence polarization supposes that as a result of binding these substances to proteins and lipids. Compound 2c displayed a continuous increase of fluorescence polarization signal in the presence of proteins (BSA, HSA), yeast cytoplasm (YC) and mitochondria (YM and RLM). This compound displayed a significant cytotoxic effect. This pattern of interaction with proteins might be one of the contributing vectors of the observed cytotoxicity against several human carcinoma cell lines.

Antioxidant dietary approach in treatment of fatty liver: New insights and updates

Non-alcoholic fatty liver disease(NAFLD) is a common clinicopathological condition, encompassing a range of conditions caused by lipid deposition within liver cells. To date, no approved drugs are available for the treatment of NAFLD, despite the fact that it represents a serious and growing clinical problem in the Western world. Identification of the molecular mechanisms leading to NAFLD-related fat accumulation, mitochondrial dysfunction and oxidative balance impairment facilitates the development of specific interventions aimed at preventing the progression of hepatic steatosis. In this review, we focus our attention on the role of dysfunctions in mitochondrial bioenergetics in the pathogenesis of fatty liver. Major data from the literature about the mitochondrial targeting of some antioxidant molecules as a potential treatment for hepatic steatosis are described and critically analysed. There is ample evidence of the positive effects of several classes of antioxidants, such as polyphenols(i.e., resveratrol, quercetin, coumestrol, anthocyanins, epigallocatechin gallate and curcumin), carotenoids(i.e., lycopene, astaxanthin and fucoxanthin) and glucosinolates(i.e., glucoraphanin, sulforaphane, sinigrin and allyl-isothiocyanate), on the reversion of fatty liver. Although the mechanism of action is not yet fully elucidated, in some cases an indirect interaction with mitochondrial metabolism is expected. We believe that such knowledge will eventually translate into the development of novel therapeutic approaches for fatty liver.

Effects of hypobaric hypoxia on adenine nucleotide pools,adenine nucleotide transporter activity and protein expression in rat liver

瞄准：在老鼠肝在 mitochondrial 能代谢上探索比重低於脑脊髓液的组织缺氧的效果。方法：成年男 Wistar 老鼠暴露于高模仿 5,000 m 的一个比重低於脑脊髓液的房间为 23 h 的高度每天为 0 (H0 ) ， 1 (H1 ) ， 5 (H5 ) ， 15 (H15 ) 并且 30 d (H30 ) 分别地。老鼠被斩首杀头牺牲，肝被移开。肝线粒体被差示离心节目孤立。在织物和线粒体的腺嘌核苷酸水池(ATP，自动数据处理，和安培) 的尺寸被高效液相色谱法(HPLC ) 分开并且测量。腺嘌核苷酸 transporter (蚂蚁) 活动被同位素的技术决定。蚂蚁全部的蛋白质水平被西方的污点决定。结果：与 H0 组相比， intra-mitochondrial ATP 内容在所有组织缺氧组减少了。然而，当时， H5 组到达了最低的点(70.6%)(P【0.01 ) 与控制组相比。Intra-mitochondrial 自动数据处理和安培水平在所有组织缺氧组显示出类似的变化并且在 H0 组是比那显著地低的。另外， extra-mitochondrial ATP 和自动数据处理内容在所有组织缺氧组显著地减少了。而且，在组 H5， H15 和 H30 的 extra-mitochondrial 安培在 H0 组是比那显著地低的，而 H1 组不与控制状况相比标记变化。当时，在组织缺氧组的蚂蚁的活动显著地减少了，它在 H5 组(55.7%)(P【0.01 ) 是最低的与 H0 相比组。在 H30 组的蚂蚁活动比在 H15 组高，但是仍然在 H0 组比那降低。在 H5 的蚂蚁蛋白质水平， H15， H30 组，与 H0 相比，组显著地减少了，在 H5，组是它最低，在 H0 是那中的 27.1% 个组织(P【0.01 ) 。在 H30 组的蚂蚁蛋白质水平比在 H15 组高，但是仍然比在 H0 组降低。结论：比重低於脑脊髓液的组织缺氧减少 mitochondrial ATP 在老鼠肝满足，当 mitochondrial ATP 水平在长期的组织缺氧暴露期间恢复时。extra-mitochondrial ATP 的底层可能在组织缺氧暴露期间与蚂蚁活动的减少有关。

Biochemical mechanisms in drug-induced liver injury:Certainties and doubts

Drug-induced liver injury is a significant and still unresolved clinical problem.Limitations to knowledge about the mechanisms of toxicity render incomplete the detection of hepatotoxic potential during preclinical development.Several xenobiotics are lipophilic substances and their transformation into hydrophilic compounds by the cytochrome P-450 system results in production of toxic metabolites.Aging,preexisting liver disease,enzyme induction or inhibition,genetic variances,local O2 supply and,above all,the intrinsic molecular properties of the drug may affect this process.Necrotic death follows antioxidant consumption and oxidation of intracellular proteins,which determine increased permeability of mitochondrial membranes,loss of potential,decreased ATP synthesis,inhibition of Ca2+-dependent ATPase,reduced capability to sequester Ca2+ within mitochondria,and membrane bleb formation.Conversely,activation of nucleases and energetic participation of mitochondria are the main intracellular mechanisms that lead to apoptosis.Non-parenchymal hepatic cells are inducers of hepatocellular injury and targets for damage.Activation of the immune system promotes idiosyncratic reactions that result in hepatic necrosis or cholestasis,in which different HLA genotypes might play a major role.This review focuses on current knowledge of the mechanisms of drug-induced liver injury and recent advances on newly discovered mechanisms of liver damage.Future perspectives including new frontiers for research are discussed.

Beneficial effects of adenosine triphosphate-sensitive K^+ channel opener on liver ischemia/reperfusion injury

AIM:To investigate the effect of diazoxide administration on liver ischemia/reperfusion injury.METHODS:Wistar male rats underwent partial liver ischemia performed by clamping the pedicle from the medium and left anterior lateral segments for 1 h under mechanical ventilation.They were divided into 3 groups:Control Group,rats submitted to liver manipulation,Saline Group,rats received saline,and Diazoxide Group,rats received intravenous injection diazoxide(3.5 mg/kg) 15 min before liver reperfusion.4 h and 24 h after reperfusion,blood was collected for determination of aspartate transaminase(AST),alanine transaminase(ALT),tumor necrosis factor(TNF-α),interleukin-6(IL-6),interleukin-10(IL-10),nitrite/nitrate,creatinine and tumor growth factor-β1(TGF-β1).Liver tissues were assembled for mitochondrial oxidation and phosphorylation,malondialdehyde(MDA) content,and histologic analysis.Pulmonary vascular permeability and myeloperoxidase(MPO) were also determined.RESULTS:Four hours after reperfusion the diazoxide group presented with significant reduction of AST(2009 ± 257 U/L vs 3523 ± 424 U/L,P = 0.005); ALT(1794 ± 295 U/L vs 3316 ± 413 U/L,P = 0.005); TNF-α(17 ± 9 pg/mL vs 152 ± 43 pg/mL,P = 0.013; IL-6(62 ± 18 pg/mL vs 281 ± 92 pg/mL); IL-10(40 ± 9 pg/mL vs 78 ± 10 pg/mL P = 0.03),and nitrite/nitrate(3.8 ± 0.9 μmol/L vs 10.2 ± 2.4 μmol/L,P = 0.025) when compared to the saline group.A significant reduction in liver mitochondrial dysfunction was observed in the diazoxide group compared to the saline group(P < 0.05).No differences in liver MDA content,serum creatinine,pulmonary vascular permeability and MPO activity were observed between groups.Twenty four hours after reperfusion the diazoxide group showed a reduction of AST(495 ± 78 U/L vs 978 ± 192 U/L,P = 0.032); ALT(335 ± 59 U/L vs 742 ± 182 U/L,P = 0.048),and TGF-β1(11 ± 1 ng/mL vs 17 ± 0.5 ng/mL,P = 0.004) serum levels when compared to the saline group.The control group did not present alterations when compared to the diazoxide and saline groups.CONCLUSION:Diazoxide maintains liver mitochondrial function,increases liver tolerance to ischemia/reperfusion injury,and reduces the systemic inflammatory response.These effects require further evaluation for using in a clinical setting.