酒客乐对酒精性肝损伤的疗效及其机制研究

[目的]探讨酒客乐对酒精性肝损伤的防治作用及其机制。[方法]采用白酒、吡唑、橄榄油的混合液制成酒精性肝损伤大鼠模型,观察酒客乐对酒精性肝损伤大鼠肝组织匀浆超氧化物歧化酶(SOD)活性、脂质过氧化代谢终产物丙二醛(MDA)水平的影响,并观察肝组织病理学改变。[结果]酒精可使大鼠肝组织SOD活性降低,MDA水平升高,而酒客乐能明显提高SOD活性(P<0.01),降低MDA的水平(P<0.05),病理观察结果能明显减轻酒精所致的肝脏损伤。[结论]酒客乐具有防治酒精性肝损伤的作用,其作用机制可能与直接抑制脂肪肝的形成、清除自由基、抗脂质过氧化等有关。     

L-精氨酸对糖尿病大鼠肝、心肌及膈肌线粒体自由基损伤的保护作用

目的探讨L-精氨酸(L-Arg)对糖尿病大鼠肝脏、心肌及膈肌线粒体自由基损伤的保护作用. 方法给大鼠腹腔注射四氧嘧啶制备糖尿病模型,随机分为糖尿病组、L-Arg治疗组及正常对照组;用药4 w末测定三组大鼠肝脏、心肌及膈肌细胞线粒体中Mn-SOD、GSH-Px活性和MDA含量及膈肌线粒体内GSH含量.结果糖尿病组较正常组,大鼠肝、心肌、膈肌线粒体内GSH-Px活性显著降低(P＜0.01,P＜0.05,P＜0.001),MDA含量显著升高(P＜0.01,P＜0.05,P＜0.01),肝、膈肌线粒体Mn-SOD活性(均P＜0.01)及膈肌线粒体GSH含量(P＜0.05)也明显降低;与模型组比较,L-Arg可显著增加糖尿病大鼠肝、心肌、膈肌线粒体GSH-Px活性(P＜0.05,P＜0.05,P＜0.001)及肝、膈肌线粒体Mn-SOD活性(均P＜0.001),并使膈肌线粒体MDA含量显著降低(P＜0.01),而GSH含量明显升高(P＜0.001). 结论糖尿病大鼠肝、心肌、膈肌线粒体内自由基生成增多;L-Arg可通过提高肝、心肌、膈肌细胞线粒体中自由基清除酶的活性来加速自由基的清除,提高机体的抗氧化能力,从而保护机体功能免受氧化损伤.     

针刺对拟痴呆大鼠脑内自由基系统酶活性的影响

目的　探讨针刺对拟 Alzheimer病 (AD)大鼠脑内自由基氧化损伤的影响。方法　应用迷宫测试观察针刺对拟 AD大鼠学习记忆能力的影响 ,应用分光光度法测定大鼠针刺前后大脑皮质中丙二醛 (MDA)含量及谷胱甘肽过氧化物酶 (GSH- Px)、超氧化物歧化酶 (SOD)活性变化。结果　针刺可改善痴呆大鼠的记忆功能障碍 ,针刺组大鼠大脑皮质中 MDA含量比模型组显著降低 (P<0 .0 1 ) ,而 SOD和 GSH- Px活性明显升高 (P<0 .0 1 )。结论　针刺具有对抗自由基所致的氧化防御系统受损和脂质过氧化水平升高的作用 ,提高脑内抗氧化能力 ,减轻脑内自由基对神经元的损伤 ,改善 AD的病理反应。     

复方中药对大鼠高脂饮食所致脂肪性肝炎肝组织氧化和抗氧化系统的影响

目的:探讨氧应激和脂质过氧化在高脂饮食所致脂肪性肝炎形成中的作用,复方中药防治非乙醇性脂肪性肝炎的作用机制.方法:雄性SD大鼠60只随机分组为6组,每组10只.正常组普通饲料喂养;模型Ⅰ组、Ⅱ组喂高脂饲料;中药治疗Ⅰ、Ⅱ组分别在喂饲高脂饲料9wk、13wk予复方中药灌胃;饮食治疗组在喂饲高脂饲料13wk后改为普通饲料喂养.12wk末处死正常组、模型Ⅰ组、中药治疗Ⅰ组大鼠;剩余3组大鼠继续喂养至16wk末处死,测定血清转氨酶(ALT、AST),全血谷胱甘肽过氧化物酶(GSH-PX),肝匀浆丙二醛(MDA)含量,超氧化物歧化酶(SOD)活性,总抗氧化能力(T-AOC),一氧化氮(NO),诱导型一氧化氮合酶(iNOS),谷胱甘肽(GSH)水平,观察肝组织学改变.结果:模型组大鼠12wk出现单纯性脂肪肝,16wk发展为脂肪性肝炎.与正常组比,模型组大鼠肝组织脂质过氧化产物MDA含量明显增多(6.45±1.07,8.38±1.32μmol/gvs5.08±0.91μmol/g,P<0.01),而抗氧化物SOD(171±14,148±26kNU/gtvs198±25kNU/gt,P<0.05和P<0.01),GSH(40.8±5.1,35.0±9.0mg/gvs48.5±7.6mg/g,P<0.05和P<0.01),GSH-PX(11.2±1.5,10.3±1.8μmol/Lvs16.4±3.7μmol/L,P<0.01)含量明显降低,且肝脏的脂肪变性严重程度随着高脂饮食喂养的时间延长而加剧.中药治疗组各项指标较模型组有明显改善(P<0.05或P<0.01),脂肪变性程度明显减轻.而饮食治疗组大鼠肝脏病理学仍呈轻-中度脂肪变性,各项指标与模型组比无显著差异.结论:氧应激和脂质过氧化在NASH形成中发挥重要作用,复方中药通过抗脂质过氧化等作用来治疗大鼠NASH.     

微生态制剂防治大鼠非酒精性脂肪肝炎模型作用机制的实验研究

目的探讨微生态制剂防治非酒精性脂肪性肝炎的作用机理。方法雄性SD大鼠50只随机分组为5组,每组10只,正常组普通饲料喂养;模型Ⅰ组、Ⅱ组喂高脂饲料;微生态制剂治疗组和饮食组分别在喂饲高脂饲料12周末予美常安灌胃和改为普通饲料喂养。12周末处死正常组、模型Ⅰ组大鼠;剩余2组大鼠继续喂养至16周末处死,测定血清转氨酶(ALT、AST),肿瘤坏死因子α(TNFα)水平,肝匀浆丙二醛(MDA)含量,超氧化物歧化酶(SOD)活性,总抗氧化能力(T-AOC),一氧化氮(NO)、诱导型一氧化氮合酶(iNOS)及谷胱甘肽(GSH)水平,观察肝组织学改变。结果模型组大鼠12周出现单纯性脂肪肝,16周发展为脂肪性肝炎。与正常组比,模型组大鼠肝组织脂质过氧化产物MDA含量明显增多(6.45±1.07,8.38±1.32μmol/gvs5.08±0.91μmol/g,P<0.01),而抗氧化物SOD(171±14,148±26kNU/gtvs198±25kKU/gt,P<0.05和P<0.01),GSH(40.8±5.1,35.0±9.0mg/gvs48.5±7.6mg/g,P<0.5和P<0.01)含量明显降低,且肝脏的脂肪变性严重程度随着高脂饮食喂养的时间延长而加剧,微生态制剂治疗组大鼠各项指标较模型组有明显改善(P<0.05或P<0.01),脂肪变性程度明显减轻,而饮食治疗组大鼠各项指标与模型组比无显著差异。结论微生态制剂美常安可能通过减轻体重,改善机体脂质代谢紊乱,抗脂质过氧化反应,抗炎等综合作用来防治非酒精性脂肪性肝炎。     

脂肪肝大鼠线粒体膜流动性改变及活血化瘀法防治的实验研究

目的:探讨脂肪肝大鼠线粒体膜流动性改变及活血化瘀法的防治作用.方法:采用高脂饲料辅以乙醇和CCl4复制脂肪肝大鼠模型,观察大鼠肝脏线粒体膜的流动性,肝组织中SOD、MDA含量及肝脂,血清肝功能,血脂等变化,并以活血化瘀法进行防治,观察其对上述指标的影响.结果:模型组肝线粒体膜流动性、SOD活性明显降低、而肝组织MDA含量、肝脂及血清ALT、AST、TG、TC显著升高,与正常组比较差异有显著性意义(P＜0.01);活血化瘀法能明显改善肝线粒体膜流动性,增强SOD活性,降低血脂、肝脂、MDA含量,改善肝功能(P＜0.05或P＜0.01).结论:脂肪肝大鼠肝脏脂质过氧化增强,线粒体膜流动性降低;活血化瘀法可通过减轻肝脏脂质过氧化并修复线粒体膜流动性,从而达到减轻肝脂变、保护肝功能的作用.     

维生素C、E对氟中毒大鼠不同组织抗氧化酶活性影响的研究

目的探讨氟中毒大鼠肝、肾、脑组织抗氧化酶类及脂质过氧化物的变化以及维生素 C、E 单独和联合干预以及不同剂量干预对高氟状态下大鼠抗氧化酶活性及脂质过氧化物的影响。方法将120只 Wistar 大鼠随机分为9绀,饮水染氟建立氟中毒大鼠模型,并灌胃给予维生素 C 和/或维生素 E;9月后处死大鼠取肝、肾、腑组织测定超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氧酶(CAT)活性和脂质过氧化物丙二醛(MDA)含量。结果染氟组大鼠肝、肾、脑组织 MDA 含量显著增加,肝和腑绀织 SOD、GSH-Px 和 CAT 活性以及肾组织 GSH-Px 活性均显著降低(P<0.05),而肾组织 SOD、CAT 活性无明显变化;维生素 C、E 可不同程度地增强 SOD、GSH-Px 和 CAT 活性,降低 MDA 水平;联合干预维生素 C、E 可明显拮抗氟诱导的脂质过氧化作用,显著增强大鼠肝组织 SOD、GSH-Px 和 CAT活性;维生素 C 低制量干预对肾脏 SOD 和 CAT 以及脑 GSH-Px 和 CAT 具有明显的保护作用;维生素 E 高剂量干预显著增加脑 SOD 活性。结论维生素 C 和维生素 E 在一定剂量范围内可有效拮抗过量氟导敛的脂质过氧化作用,对氟中毒大鼠肝、肾、脑组织有明显的保护作用。     

车前子对高脂血症大鼠机体自由基防御机能的影响

目的 观察车前子对高脂血症大鼠心、肝组织自由基防御机能的影响。方法 健康大鼠饲以高脂饲料同时添加不同浓度车前子，喂饲12w后测其心、肝组织中丙二醛(MDA)、超氧化物歧化酶(SOD)，过氧化氢酶(CAT)以及谷胱苷肽过氧化物酶(GSH-Px)活性。结果 车前子能明显降低心肌MDA含量，升高心脏中的SOD活性及肝组织中CAT和GSH-Px活性。结论 车前子对机体自由基的防御机能可产生一定的影响，对动脉粥样硬化和冠心病具有一定的防治作用。     

姜黄素对酒精诱导的大鼠脂质过氧化反应的影响

目的:观察姜黄素对酒精性肝病大鼠肝脏氧化应激指标SOD,MDA和NO及血清ALT,AST和ALP水平的影响,探讨姜黄素对酒精诱导的大鼠脂质过氧化反应的影响.方法:将40只SD大鼠随机分为对照组、模型组、姜黄素治疗Ⅰ组(40 mg/kg)、姜黄素治疗Ⅱ组(80 mg/kg)和姜黄素治疗Ⅲ组(160mg/kg),每组8只.除对照组用等量生理盐水灌胃外,其他组均采用56度白酒6.72 g/(kg·d)灌胃的方法制作酒精性肝病大鼠模型,6 wk后姜黄素治疗Ⅰ、Ⅱ、Ⅲ组分别加用姜黄素ig,至12 wk末,处死大鼠,抽取血标本测定血清ALT、AST及ALP水平;留取肝组织标本测定SOD活性、MDA及NO含量,常规HE染色观察肝脏病理变化.结果:与对照组相比,模型组大鼠血清ALT、AST及ALP水平显著升高(86.4±7.5 vs 33.5±10.3;201.0±16.8 vs 116.5±12.0;205.1±20.0 vs 104.6±9.4:均P<0.01);肝组织SOD活性明显下降(80.21±4.55 vs 180.24±27.53,P<0.01),MDA及NO含量显著升高(3.29±0.34vs 1.35±0.12;4.37±0.21 vs 2.72±0.13:均P<0.01).与模型组相比,各姜黄素治疗组血清ALT、AST及ALP水平(Ⅰ组:66.5±9.6,171.4±10.8,176.4±13.7:Ⅱ组:52.4±12.0,145.8±11.9,146.9±13.8:Ⅲ组:40.9±7.9,135.0±11.8,127.1±12.6)明显降低(P<0.05或P<0.01),肝组织MDA及NO含量(Ⅰ组:2.84±0.27,4.01±0.17;Ⅱ组:1.95±0.23,3.60±0.16;Ⅲ组:1.65±0.08,3.22±0.13)均显著降低(P<0.05或P<0.01),而SOD活性(92.36±6.47,117.69±21.96,146.70±27.361明显提高(P<0.05或P<0.01),其中以Ⅱ、Ⅲ治疗组较为显著.模型组大鼠肝细胞出现不同程度的脂肪变性,伴有点、灶状坏死,炎性细胞浸润,各姜黄素治疗组肝脏病理变化不同程度的轻于模型组.结论:姜黄素能抑制脂质过氧化,减轻或防治酒精诱导的肝损伤.     

蝇蛆肽对衰老小鼠的抗氧化作用

目的探讨蝇蛆肽对衰老模型小鼠的抗氧化作用。方法建立D-半乳糖(D-gal)衰老小鼠模型,将3月龄小鼠分为正常对照组(K组),模型组(A组),维生素C组(V组),蝇蛆肽低、中、高剂量组(L组、M组、H组)。各处理组灌胃7 w后,测定胸腺、脾脏和肝脏指数,测定血清、肝脏和脑组织中超氧化物歧化酶(SOD)、丙二醛(MDA)、过氧化氢酶(CAT)及肝脏和脑组织的谷胱甘肽过氧化物酶(GSH-Px)。结果与A组比较,M、H组胸腺、脾脏和肝脏指数显著升高(P<0.05或P<0.01),血清、肝脏和脑组织中SOD、CAT活性显著升高和MDA含量显著降低(P<0.05或P<0.01),肝脏和脑组织中GSH-Px活性显著升高(P<0.05或P<0.01)。结论蝇蛆肽具有较好的抗氧化活性,其可能通过增强机体内抗氧化物酶活性和自由基的清除,从而减少脂质过氧化物的生成,发挥抗脂质过氧化作用。     

Mechanisms for experimental buprenorphine hepatotoxicity: major role of mitochondrial dysfunction versus metabolic activation

BACKGROUND/AIMS: Although sublingual buprenorphine is safely used as a substitution drug in heroin addicts, large overdoses or intravenous misuse may cause hepatitis. Buprenorphine is N-dealkylated to norbuprenorphine by CYP3A. METHODS: We investigated the mitochondrial effects and metabolic activation of buprenorphine in isolated rat liver mitochondria and microsomes, and its toxicity in isolated rat hepatocytes and treated mice. RESULTS: Whereas norbuprenorphine had few mitochondrial effects, buprenorphine (25-200 microM) concentrated in mitochondria, collapsed the membrane potential, inhibited beta-oxidation, and both uncoupled and inhibited respiration in rat liver mitochondria. Both buprenorphine and norbuprenorphine (200 microM) underwent CYP3A-mediated covalent binding to rat liver microsomal proteins and both caused moderate glutathione depletion and increased cell calcium in isolated rat hepatocytes, but only buprenorphine also depleted cell adenosine triphosphate (ATP) and caused necrotic cell death. Four hours after buprenorphine administration to mice (100 nmol/g body weight), hepatic glutathione was unchanged, while ATP was decreased and serum transaminase increased. This transaminase increase was attenuated by a CYP3A inducer and aggravated by a CYP3A inhibitor. CONCLUSIONS: Both buprenorphine and norbuprenorphine undergo metabolic activation, but only buprenorphine impairs mitochondrial respiration and ATP formation. The hepatotoxicity of high concentrations or doses of buprenorphine is mainly related to its mitochondrial effects.     

Opposite and tissue-specific effects of coenzyme Q2 on mPTP opening and ROS production between heart and liver mitochondria: role of complex I

Coenzyme Q(2) (CoQ(2)) is known to inhibit mitochondrial permeability transition pore (mPTP) opening in isolated rat liver mitochondria. In this study, we investigated and compared the effects of CoQ(2) on mPTP opening and ROS production in isolated rabbit heart and rat liver mitochondria. Mitochondria were isolated from New Zealand White rabbit hearts and Wistar rat livers. Oxygen consumption, Ca(2+)-induced mPTP opening, ROS production and NADH DUb-reductase activity were measured. Rotenone was used to investigate the effect of CoQ(2) on respiratory complex I activity. CoQ(2) (23 μM) reduced the respiratory control index by 32% and 57% (p<0.01) in heart and liver mitochondria respectively, mainly through an increased oxygen consumption in state 4. CoQ(2) induced a 60% (p<0.05) decrease of calcium retention capacity (CRC) in heart mitochondria and inversely a 46% (p<0.05) increase in liver mitochondria. In basal condition, CoQ(2) induced a 170% (p<0.05) increase of H(2)O(2) production in heart mitochondria and 21% (ns) decrease of H(2)O(2) production in liver mitochondria. Because rotenone, a complex I inhibitor, increases H(2)O(2) production in heart but not in liver mitochondria we investigated the CoQ(2) effect in a dose-response assay of complex I inhibition by rotenone in both mitochondria. CoQ(2) antagonized the effect of rotenone on respiratory complex I activity in liver but not in heart mitochondria. CoQ(2) significantly reduced NADH DUb-reductase activity in liver (-47%) and heart (-37%) mitochondria. In conclusion, our data showed that on the contrary to what was observed in liver mitochondria, CoQ(2) favors mPTP opening and ROS production in heart mitochondria through an opposite effect on respiratory complex I activity.     

砷中毒大鼠肝脏亚细胞组分中砷的分布

目的　研究砷中毒大鼠肝脏亚细胞组分 (细胞核、线粒体、溶酶体、微粒体及胞液 )中砷的分布 ,为地方性砷中毒的治疗提供科学依据。方法　用亚砷酸钠 (Na As O2 )诱导出大鼠亚急性砷中毒模型 ,采用差速离心生化分离技术与超热中子活化分析相结合 ,测定大鼠肝脏亚细胞组分中砷的含量。结果　中毒组大鼠肝脏中各亚细胞组分中砷的含量均极显著高于正常对照组 (P <0 .0 1或 P <0 .0 0 1) ;且砷在各亚细胞组分中的浓度并非均匀分布 ,在中毒组肝脏亚细胞中的浓度遵循微粒体 >胞液 >线粒体 >细胞核。结论　砷在微粒体、胞液和细胞核中的大量蓄积 ,可能导致肝细胞损伤。     

Uncoupling of rat and human mitochondria: A possible explanation for tacrine-induced liver dysfunction

BACKGROUND & AIMS: Tacrine administration (1-3 mg/kg) may lead to sinusoidal concentrations in the micromolar range and produce liver dysfunction in 50% of recipients. The aim of this study was to determine the cellular effects of tacrine that account for liver dysfunction. METHODS: The effects of tacrine on mitochondrial function were determined in isolated rat liver mitochondria, cultured rat hepatocytes, and isolated human lymphocytes. RESULTS: In vitro, tacrine was taken up by rat liver mitochondria, decreased their membrane potential, and stimulated their respiration. Ex vivo, respiration was increased in rat mitochondria isolated 30 minutes after the administration of 2 mg of tacrine per kilogram. After 7 days of culture, tacrine (2.5 mumol/L) decreased rat hepatocyte adenosine triphosphate levels. Ten micromolar decreased 3-(4,5-dimethylthiazol-2- yl)-2,5-diphenyltetrazolium reduction and neutral red uptake without modifying cell glutathione, the morphology of the endoplasmic reticulum, or protein synthesis. Tacrine (1.25 mumol/L) decreased levels of adenosine triphosphate in human lymphocytes. CONCLUSIONS: The weak base tacrine exerts a protonophoric effect in mitochondria that wastes energy and decreases levels of adenosine triphosphate in rat and human cells. These effects are visible after clinically relevant doses of tacrine and might be involved in tacrine-induced liver dysfunction. (Gastroenterology 1996 Jun;110(6):1878-90)     

Precipitating Antimitochondrial Antibodies in Japanese Patients with Primary Biliary Cirrhosis

The prevalence of three precipitating antibodies to mitochondria A (M-A), mitochondria B (M-B), and mitochondria C (M-C), reacting with the antigens in the mitochondrial fraction of sonicated rat liver was studied in Japanese patients with primary biliary cirrhosis and other liver diseases. Antibodies to M-A and M-B were found in 12 of 22 (54%) and 11 of 22 (50%) patients, respectively. Antibodies to M-C were found in only one of 22 (4%) patients. The titers of antibodies to M-A and M-B correlated with the titers of mitochondrial immunofluorescence staining on unfixed mouse kidney section (r = 0.71 and 0.81, respectively). These antibodies were not present in liver cirrhosis (20 patients), chronic active hepatitis (20), acute viral hepatitis (10), and hepatoma (10). However, the titers of these antibodies did not correlate with amount of immunoglobulin, immune complexes, and the severity of disease. This work confirms that the antibodies to M-A and M-B are also marker antibodies for Japanese patients with primary biliary cirrhosis.     

Substrate oxidation and energy production by Guerin epithelioma mitochondria.

The mitochondria from Guerin epithelioma and normal rat liver were isolated and their energy production abilities were compared. Both mitochondrial preparations were of the same degree of purity. The percentage of mitochondrial protein in tumour homogenates was three times lower than in rat liver. Guerin epithelioma mitochondria characterized a high respiratory control ratio with succinate and low with NAD dependent substrates in the presence of ADP. The ADP-ATP exchange rate was five times lower in tumour than in rat liver. Energy dependent potassium ions accumulation was about 45% of that found in rat liver mitochondria. The uptake of respiratory substrates was similar in tumour and liver mitochondria. These results indicate on the low efficiency of oxidative phosphorylation in the mitochondria of Guerin epithelioma.     

Role of mitochondrial lactate dehydrogenase and lactate oxidation in the intracellular lactate shuttle

To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate clearance and oxidation in vivo, isolated rat liver, cardiac, and skeletal muscle mitochondria were incubated with lactate, pyruvate, glutamate, and succinate. As well, α-cyano-4-hydroxycinnamate (CINN), a known monocarboxylate transport inhibitor, and oxamate, a known LDH inhibitor were used. Mitochondria readily oxidized pyruvate and lactate, with similar state 3 and 4 respiratory rates, respiratory control (state 3/state 4), and ADP/O ratios. With lactate or pyruvate as substrates, α-cyano-4-hydroxycinnamate blocked the respiratory response to added ADP, but the block was bypassed by addition of glutamate (complex I-linked) and succinate (complex II-linked) substrates. Oxamate increased pyruvate (≈10–40%), but blocked lactate oxidation. Gel electrophoresis and electron microscopy indicated LDH isoenzyme distribution patterns to display tissue specificity, but the LDH isoenzyme patterns in isolated mitochondria were distinct from those in surrounding cell compartments. In heart, LDH-1 (H4) was concentrated in mitochondria whereas LDH-5 (M4) was present in both mitochondria and surrounding cytosol and organelles. LDH-5 predominated in liver but was more abundant in mitochondria than elsewhere. Because lactate exceeds cytosolic pyruvate concentration by an order of magnitude, we conclude that lactate is the predominant monocarboxylate oxidized by mitochondria in vivo. Mammalian liver and striated muscle mitochondria can oxidize exogenous lactate because of an internal LDH pool that facilitates lactate oxidation.     

Oxidation and Phosphorylation Reactions in Isolated Liver Mitochondria in Normal and Icteric Conditions

Mitochondria were isolated from human liver biopsies obtained during surgical operations in patients with cholelithiasis or duodenal or gastric ulcer. Respiration with succinate, alpha-ketoglutarate or pyruvate + malate, respiratory control and P/O ratios were determined and compared with corresponding data for isolated rat liver mitochondria. It was found that in human liver mitochondria there was a faster oxygen uptake with succinate as substrate than in rat liver mitochondria. The oxygen uptake was somewhat less with alpha-ketoglutarate or pyruvate + malate. Respiratory control and P/O ratios were high for both preparations.

Non-stimulated ATPase¹ activity was low but increased in the basic pH range in accordance with earlier reports on rat liver mitochondria. Stimulation by physiologically occurring agents, viz. fatty acids and cholic acid and, with somewhat varying results, bilirubin, caused increases of ATPase activity at pH 7-8 while 2.4-dinitrophenol seemed to cause activation at other pH’s also. The stimulatory concentration ranges for the compounds tested were in agreement with those demonstrated earlier for rat liver mitochondria.

In eleven patients with icterus of varying degree, caused by choledocholithiasis or carcinoma of the pancreas, respiration in liver mitochondria with alpha-ketoglutarate and pyruvate + malate was significantly diminished, while succinate respiration was maintained. Respiratory control was found to be lowered and ATPase activity increased.

The results indicate that in cholestasis in the human, mitochondrial function is impaired in vivo in analogy with earlier findings in vitro, where bilirubin and other detergents have been added to rat liver mitochondria.     

Severe hyperthyroidism induces mitochondria-mediated apoptosis in rat liver

Thyrotoxicosis may be associated with a variety of abnormalities of liver function. The pathogenesis of hepatic dysfunction in thyrotoxicosis is unknown, but has been attributed to mitochondrial dysfunction. We studied the effect of altered thyroid function on the apoptotic index in rat liver. Extensive DNA fragmentation and significantly increased caspase-3 activity (P <.001) and caspase-9 activation (P <.005) were observed in hyperthyroid rat liver; cell death by apoptosis was confirmed. In hyperthyroid rat liver, 60% of mitochondria exhibited disruption of their outer membranes and a decrease in the number of cristae. These findings, along with significant translocation of cytochrome c and second mitochondria-derived activator of caspases to cytosol (P <.005), suggest activation of a mitochondrial-mediated pathway. However, no change in the expression levels of Bcl-2, Bax, and Bcl-x(L) were found in hyperthyroidism. For in vitro experiments, rat liver mitochondria were isolated and purified in sucrose density gradients and were treated with triiodothyronine (T3; 2-8 microM). T3 treatment resulted in an abrupt increase in mitochondrial permeability transition. Using a cell-free apoptosis system, the apoptogenic nature of proteins released from mitochondria was confirmed by observing changes in nuclear morphologic features and DNA fragmentation. Proteins released by 6 microM T3 contained significantly increased amounts of cytochrome c (P <.01) and induced apoptotic changes in 67% of nuclei. In conclusion, using in vivo and in vitro approaches, we provide evidence that excess T3 causes liver dysfunction by inducing apoptosis, as a result of activation of a mitochondria-dependent pathway. Thus, the results of this study provide an explanation for liver dysfunction associated with hyperthyroidism.     

Mitochondrial ATPase of Zajdela hepatoma. II. Mitochondria of Zajdela hepatoma contain less adenosine triphosphatase than mitochondria of rat liver.

The specific activity and the content of ATPase in mitochondria of rat liver and Zajdela hepatoma were compared. The specific activity of ATPase in sonicated mitochondria and in mitochondrial membrane fraction of rat liver was almost two times higher than the specific activity in the corresponding fraction of Zajdela hepatoma. Accordingly, the autovertin binding capacity of rat liver mitochondrial membrane fraction as well as the yield of F1-ATPase from this fraction were about two times higher than those of the mitochondrial membrane fraction of Zajdela hepatoma. The results show that mitochondria of Zajdela Hapatoma possess about half amount of ATPase present in rat liver mitochondria.