银杏叶提取物对糖尿病大鼠心肌线粒体的保护作用

目的观察银杏叶提取物(EGb)对糖尿病大鼠心肌线粒体的保护作用。方法40只SD大鼠随机分为正常对照组、糖尿病组和EGb治疗组，观察各组大鼠心肌线粒体超微结构，检测心肌线粒体琥珀酸脱氢酶(SDH)、超氧化物歧化酶(SOD)、一氧化氮合酶(NOS)的活性，以及一氧化氮(NO)、丙二醛(MDA)的含量。结果糖尿病大鼠心肌线粒体主要表现为肿胀，嵴变短，空泡化；SDH、SOD活性下降，NOS活性及MDA、NO含量增高。EGb治疗组病变较糖尿病组明显减轻，心肌线粒体SDH、SOD活性升高，NOS活性及NO、MDA含量下降。结论EGb能保护自由基和过量一氧化氮对心肌线粒体的损伤，提高SDH活性，从而对糖尿病大鼠心肌起保护作用。     

消瘿强肌汤对甲状腺机能亢进性肌病骨骼肌线粒体的影响

目的观察消瘿强肌汤对甲状腺机能亢进性肌病大鼠骨骼肌线粒体的影响,探讨消瘿强肌汤治疗甲亢肌病的机理。方法健康雌性Wistar大鼠随机分为4组：甲亢肌病模型组每日腹腔注射甲状腺激素钠盐250μg/100g造模,中药组在造模后灌服消瘿强肌汤30d,生理盐水对照组造模后灌服生理盐水30d,正常对照组每天腹腔注射生理盐水。各组取骨骼肌观察琥珀酸脱氢酶活性和含量的变化,透射电镜观察骨骼肌及线粒体的形态变化。结果甲亢肌病模型组骨骼肌琥珀酸脱氢酶呈色降低,含量下降。超微结构显示线粒体嵴断裂,甚至融合消失。中药组可见酶活性和含量恢复,线粒体嵴排列规则,空泡消失。结论消瘿强肌汤可通过恢复线粒体酶活性和线粒体结构来改善甲亢肌病的骨骼肌功能。     

Chlorphentermine-induced biochemical alterations in mitochondrial membranes

The effects of chlorphentermine (CP) on bioenergetics and monoamine oxidase activity in rat liver mitochondria were examined. Oxidation rates of isocitrate, glutamate and succinate were investigated in the presence of CP (0.5-5.0 mM). In the presence of low concentrations (0.5-2.0 mM) CP decreased respiratory control ratio and ADP/O ratio, and stimulated state 4 respiration. State 3 respiration and uncoupled state were unaffected. The same pattern of changes was found after in vivo CP treatment for 1 or 2 weeks (30 mg/kg i.p., 5 days/week). CP also increased respiration in state 3 that had been inhibited previously by oligomycin. These data indicate that CP functions as an uncoupler of oxidative phosphorylation. In the presence of higher concentrations of CP (3.0-5.0 mM), respiration in states 4, 3 and in uncoupled state, as well as respiratory control ratio and ADP/O, were decreased. Oxidation of norepinephrine, serotonin, tyramine and dopamine by monoamine oxidase, an enzyme marker of the outer mitochondrial membrane, was inhibited in the presence of 0.05 to 0.5 mM CP. Tryptamine and benzylamine oxidation was unaffected. A kinetic study of serotonin oxidation in the absence and presence of CP (0.05-0.25 mM) indicated that both the Vmax and Km were affected. This drug is an inhibitor of liver mitochondrial monoamine oxidase with mixed-type inhibition. These combined data show that CP affects biochemical processes in both inner and outer mitochondrial membranes.     

Alterations in skeletal muscle indicators of mitochondrial structure and biogenesis in patients with type 2 diabetes and heart failure: effects of epicatechin rich cocoa

(-)-Epicatechin (Epi), a flavanol in cacao stimulates mitochondrial volume and cristae density and protein markers of skeletal muscle (SkM) mitochondrial biogenesis in mice. Type 2 diabetes mellitus (DM2) and heart failure (HF) are diseases associated with defects in SkM mitochondrial structure/function. A study was implemented to assess perturbations and to determine the effects of Epi-rich cocoa in SkM mitochondrial structure and mediators of biogenesis. Five patients with DM2 and stage II/III HF consumed dark chocolate and a beverage containing approximately 100 mg of Epi per day for 3 months. We assessed changes in protein and/or activity levels of oxidative phosphorylation proteins, porin, mitofilin, nNOS, nitric oxide, cGMP, SIRT1, PGC1α, Tfam, and mitochondria volume and cristae abundance by electron microscopy from SkM. Apparent major losses in normal mitochondria structure were observed before treatment. Epi-rich cocoa increased protein and/or activity of mediators of biogenesis and cristae abundance while not changing mitochondrial volume density. Epi-rich cocoa treatment improves SkM mitochondrial structure and in an orchestrated manner, increases molecular markers of mitochondrial biogenesis resulting in enhanced cristae density. Future controlled studies are warranted using Epi-rich cocoa (or pure Epi) to translate improved mitochondrial structure into enhanced cardiac and/or SkM muscle function.     

Chronic cold exposure affects the antioxidant defense system in various rat tissues

BACKGROUND: Chronic exposure to stress alters the normal body homeostasis and, hence, leads to the development of various human pathologies, which might involve alterations in the antioxidant defense system. We studied the effect of chronic cold exposure on oxidative stress and antioxidant defense system in various rat tissues. METHODS: Male albino rats (Wistar strain), 2-3 months old, were exposed to 3 weeks of cold treatment. Antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) were measured in addition to the antioxidants, ascorbic acid (AsA) and glutathione (GSH), and the prooxidants, lipid peroxides (LPO) and xanthine oxidase (XOD), in brain, heart, kidney, liver and small intestine using standard protocols. RESULTS: Chronic cold exposure resulted in a significant increase in LPO in all the tissues studied while XOD was increased in the brain and intestine. Total SOD activity was significantly decreased in all the tissues, whereas CAT activity was significantly increased in the kidney and decreased in heart, liver and intestine in the animals exposed to cold. GPx activity was increased only in the brain and intestine of stressed rats. Chronic cold exposure resulted in significant decrease in GR activity in heart, liver and intestine. GST activity was increased (except heart) and GSH was significantly decreased in all the tissues in treated rats. AsA was increased in kidney and intestine but decreased in heart of stressed animals. CONCLUSIONS: The observed changes in the antioxidant defense system are tissue specific, but it is evident that chronic exposure to cold leads to oxidative stress by displacing the prooxidant-antioxidant balance of this defense system by increasing the prooxidants while depleting the antioxidant capacities.     

The evaluation of altered redox status in plasma and mitochondria of acute and chronic diabetic rats

OBJECTIVES: An increase in plasma oxidative stress and decreased mitochondrial lipid hydroperoxides may contribute to the imbalance in the redox status between intramitochondrial and extramitochondrial milieu in chronic experimental diabetic rats. DESIGN AND METHODS: To determine the effect of hyperglycemia in promoting redox imbalance, we determined lipid hydroperoxides (LHP), protein carbonyl (PCO), total antioxidant activity (ferric reducing/antioxidant power; FRAP) and albumin as markers of redox status of plasma, and mitochondrial lipid hydroperoxide levels as a marker of lipid peroxidation in liver, pancreas and kidney tissue of acute and chronic diabetic male Sprague-Dawley rats and their controls. The levels of the studied markers were determined by colorimetric methods. RESULTS: Plasma and mitochondrial oxidative stress parameter levels of acute diabetic rats were not significantly different from their controls. Plasma LHP and PCO levels of chronic diabetic rats were increased significantly as compared to those of both acute diabetic rats and the controls. Plasma FRAP levels of chronic diabetic animals were decreased significantly as compared to those of the controls. On the other hand, LHP levels in liver, pancreas and kidney mitochondria of chronic diabetic rats were decreased significantly as compared to those of both acute diabetic rats and the controls. We observed a negative correlation between LHP levels in liver mitochondria of chronic diabetic rats, and PCO and fructosamine levels in plasma of chronic diabetic rats were correlated. LHP levels in the pancreatic mitochondria of chronic diabetic rats and plasma oxidative stress parameters of chronic diabetic rats were not significantly correlated. LHP levels in kidney mitochondria of chronic diabetic rats were significantly correlated with serum albumin. There was no correlation between LHP levels in kidney mitochondria and other plasma oxidative stress parameters in chronic diabetic rats. CONCLUSIONS: Our data suggest that redox imbalance between plasma and liver mitochondria might become a major threat to chronic diabetic rats.     

内毒素休克大鼠肝线粒体H~ -ATP酶活性变化及其与氧自由基的关系

目的　本研究旨在探讨内毒素休克时肝线粒体H -ATP酶和脂质过氧化的改变。方法　成年健康Wistar大鼠 80只 ,随机分为内毒素注射前、内毒素注射后 1、3、5、8h组及其对照组 ;予各组相应时相点活杀取肝组织制备线粒体 ,测定线粒体H -ATP酶、MDA及血浆MDA含量。离体实验采用正常鼠肝线粒体和不同剂量的氧自由基生成剂 (FeSO4 /VitC)共同孵育后 ,测量H -ATP酶活性。结果　内毒素休克早期线粒体H -ATP酶活性升高 ,3h时其酶活性升高 15 6 % ,8h时降至对照组的 6 5 %。内毒素休克早期肝线粒体MDA含量就显著增高 ,随着休克时间延长而加重 ,8h时为对照组的 1 79倍。离体实验显示 ,小剂量FeSO4 /VitC引起的H -ATP酶活性升高 ,大剂量引起H -ATP酶活性下降 ,和在体实验结果平行。结论　内毒素休克早期H -ATP酶升高 ,晚期H -ATP酶活性降低。内毒素休克时脂质过氧化物进行性增加 ,脂质过氧化可能是H -ATP酶下降的重要原因     

Increased hepatic mitochondrial capacity in rats with hydroxy-cobalamin[c-lactam]-induced methylmalonic aciduria.

Treatment of rats with the vitamin B12 analogue hydroxy-cobalamin[c-lactam] (HCCL) impairs methylmalonyl-CoA mutase function and leads to methylmalonic aciduria due to intracellular accumulation of propionyl and methylmalonyl-CoA. Since accumulation of these acyl-CoAs disrupts normal cellular regulation, the present investigation characterized metabolism in hepatocytes and liver mitochondria from rats treated subcutaneously with HCCL or saline (control) by osmotic minipump. Consistent with decreased methylmalonyl-CoA mutase activity, 14CO2 production from 1-14C-propionate (1 mM) was decreased by 76% and 82% after 2-3 wk and 5-6 wk of HCCL treatment, respectively. In contrast, after 5-6 wk of HCCL treatment, 14CO2 production from 1-14C-pyruvate (10 mM) and 1-14C-palmitate (0.8 mM) were increased by 45% and 49%, respectively. In isolated liver mitochondria, state 3 oxidation rates were unchanged or decreased, and activities of the mitochondrial enzymes, citrate synthetase, succinate dehydrogenase, carnitine palmitoyltransferase, and glutamate dehydrogenase (expressed per milligram mitochondrial protein) were unaffected by HCCL treatment. In contrast, activities of the same enzymes were significantly increased in both liver homogenate (expressed per gram liver) and isolated hepatocytes (expressed per 10(6) cells) from HCCL-treated rats. The mitochondrial protein per gram liver, calculated on the basis of the recovery of the mitochondrial enzymes, increased by 39% in 5-6 wk HCCL-treated rats. Activities of lactate dehydrogenase, catalase, cyanide-insensitive palmitoyl-CoA oxidation, and arylsulfatase A in liver were not affected by HCCL treatment. Hepatic levels of mitochondrial mRNAs were elevated up to 10-fold in HCCL-treated animals as assessed by Northern blot analysis. Thus, HCCL treatment is associated with enhanced mitochondrial oxidative capacity and an increased mitochondrial protein content per gram liver. Increased mitochondrial oxidative capacity may be a compensatory mechanism in response to the metabolic insult induced by HCCL administration.     

Stabilization of pulmonary mitochondrial enzyme system by capsaicin during benzo(a)pyrene induced experimental lung cancer

The modulatory efficacy of capsaicin on lung mitochondrial enzyme system with reference to mitochondrial lipid peroxidation (LPO), antioxidants, key citric acid cycle enzymes and respiratory chain enzymes during benzo(a)pyrene (B(a)P) induced lung cancer in Swiss albino mice was studied. Elevations in mitochondrial LPO along with decrements in enzymic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST)), non-enzymic antioxidants (reduced glutathione (GSH), vitamin C, vitamin E and vitamin A), citric acid cycle enzymes (isocitrate dehydrogenase (ICDH), alpha-ketoglutarate dehydrogenase (alpha-KDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH)), and respiratory chain enzymes (NADH dehydrogenase and Cytochrome c oxidase) were observed in B(a)P (50mg/kg body weight) administered animals. CAP (10mg/kg body weight) pretreatment decreased lung mitochondrial LPO and augmented the activities of enzymic, non-enzymic antioxidants, citric acid cycle enzymes and respiratory chain enzymes to near normalcy revealing its chemoprotective function during B(a)P induced lung cancer.     

Deficiency of the reduced nicotinamide adenine dinucleotide dehydrogenase component of complex I of mitochondrial electron transport. Fatal infantile lactic acidosis and hypermetabolism with skeletal-cardiac myopathy and encephalopathy.

A mitochondrial defect was investigated in an infant with fatal congenital lactic acidosis (3-14 mM), high lactate-to-pyruvate ratio, hypotonia, and cardiomyopathy. His sister had died with a similar disorder. Resting oxygen consumption was 150% of controls. Pathological findings included increased numbers of skeletal muscle mitochondria (many with proliferated, concentric cristae), cardiomegaly, fatty infiltration of the viscera, and spongy encephalopathy. Mitochondria from liver and muscle biopsies oxidized NADH-linked substrates at rates 20-50% of controls, whereas succinate oxidation by muscle mitochondria was increased. Mitochondrial NADH dehydrogenase activity (complex I, assayed as rotenone-sensitive NADH oxidase, NADH-duroquinone reductase, and NADH-cytochrome c reductase) was 0-10% of controls, and NADH-ferricyanide reductase activity was 25-50% of controls in the mitochondria and in skin fibroblasts. Activities of other electron transport complexes and related enzymes were normal. Familial deficiency of a component of mitochondrial NADH dehydrogenase (complex I) proximal to the rotenone-sensitive site thus accounts for this disorder.     

Effect of chronic ethanol feeding on glutathione and functional integrity of mitochondria in periportal and perivenous rat hepatocytes.

Chronic ethanol feeding selectively impairs the translocation of cytosol GSH into the mitochondrial matrix. Since ethanol-induced liver cell injury is preferentially localized in the centrilobular area, we examined the hepatic acinar distribution of mitochondrial GSH transport in ethanol-fed rats. Enriched periportal (PP) and perivenous (PV) hepatocytes from pair- and ethanol-fed rats were prepared as well as mitochondria from these cells. The mitochondrial pool size of GSH was decreased in both PP and PV cells from ethanol-fed rats either as expressed per 10(6) cells or per microliter of mitochondrial matrix volume. The rate of reaccumulation of mitochondrial GSH and the linear relationship of mitochondrial to cytosol GSH from ethanol-fed mitochondria were lower for both PP and PV cells, effects observed more prominently in the PV cells. Mitochondrial functional integrity was lower in both PP and PV ethanol-fed rats, which was associated with decreased cellular ATP levels and mitochondrial membrane potential, effects which were greater in the PV cells. Mitochondrial GSH depletion by ethanol feeding preceded the onset of functional changes in mitochondria, suggesting that mitochondrial GSH is critical in maintaining a functionally competent organelle and that the greater depletion of mitochondrial GSH by ethanol feeding in PV cells could contribute to the pathogenesis of alcoholic liver disease.     

Zidovudine induces molecular, biochemical, and ultrastructural changes in rat skeletal muscle mitochondria.

Zidovudine (AZT) inhibits HIV-1 replication in AIDS. A limiting side effect is AZT-induced toxic myopathy. Molecular changes in a rat model of AZT-induced toxic myopathy in vivo helped define pathogenetic molecular, biochemical, and ultrastructural toxic events in skeletal muscle and supported clinical and in vitro findings. After 35 d of AZT treatment, selective changes in rat striated muscle were localized ultrastructurally to mitochondria, and included swelling, cristae disruption, and myelin figures. Decreased muscle mitochondrial (mt) DNA, mtRNA, and decreased mitochondrial polypeptide synthesis in vitro were found in parallel. Mitochondrial molecular changes occurred in absence of altered abundance of cytosolic glyceraldehyde-3-phosphate dehydrogenase, or sarcomeric mitochondrial creatine kinase mRNAs. Quadriceps mitochondrial DNA polymerase gamma activity was similar in both AZT-treated and control rats. In vivo findings with rats support the hypothesis that AZT-induced inhibition of mtDNA replication has an effect of depressing the abundance of striated muscle mtDNA, mtRNA, and mitochondrial polypeptide synthesis. This experimental approach may be useful to examine mitochondrial or toxic myopathies.     

(E)‐2‐benzylidene‐4‐phenyl‐1,3‐diselenole has antioxidant and hepatoprotective properties against oxidative damage induced by 2‐nitropropane in rats

The in vitro effect of (E)‐2‐benzylidene‐4‐phenyl‐1,3‐diselenole (BPD) was evaluated through iron/EDTA‐induced thiobarbituric acid reactive species (TBARS) and reactive species (RS) determinations as well as of the scavenging 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) radical quantification. BPD at the concentrations of 10 and 50 μΜ decreased RS and TBARS levels, respectively. The antioxidant activity was not related to the scavenging DPPH radical mechanism. A second objective of this study was to investigate the hepatoprotective action of BPD, administered by oral route, against oxidative damage induced by 2‐nitropropane (2‐NP) (100 mg/kg of body weight) in liver of rats. At the dose of 50 mg/kg, BPD protected against the increase in aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activities induced by 2‐NP. BPD (10 and 50 mg/kg) protected against the increase in TBARS levels and alkaline phosphatase (ALP) activity. Sections of liver from 2‐NP‐exposed rats presented intense infiltration of inflammatory cells and loss of cellular architecture. BPD (10 and 50 mg/kg) attenuated 2‐NP‐induced hepatic histological alterations. The inhibition of δ‐aminolevulinic dehydratase (δ‐ALA‐D), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S‐transferase (GST) activities and the decreased GSH levels caused by 2‐NP were protected by BPD (50 mg/kg). Catalase activity and ascorbic acid levels were not altered by 2‐NP. These results demonstrated the antioxidant and hepatoprotective effects of BPD in liver of rats.     

The anti-inflammatory drug, nimesulide (4-nitro-2-phenoxymethane-sulfoanilide), uncouples mitochondria and induces mitochondrial permeability transition in human hepatoma cells: protection by albumin

Like other nonsteroidal anti-inflammatory drugs, nimesulide (4-nitro-2-phenoxymethane-sulfoanilide) triggers hepatitis in a few recipients. Although nimesulide has been shown to uncouple mitochondrial respiration and cause hepatocyte necrosis in the absence of albumin, mechanisms for cell death are incompletely understood, and comparisons with human concentrations are difficult because 99% of nimesulide is albumin-bound. We studied the effects of nimesulide, with or without a physiological concentration of albumin, in isolated rat liver mitochondria or microsomes and in human hepatoma cells. Nimesulide did not undergo monoelectronic nitro reduction in microsomes. In mitochondria incubated without albumin, nimesulide (50 microM) decreased the mitochondrial membrane potential (DeltaPsim), increased basal respiration, and potentiated the mitochondrial permeability transition (MPT) triggered by calcium preloading. In HUH-7 cells incubated for 24 h without albumin, nimesulide (1 mM) decreased the DeltaPsim and cell NADPH and increased the glutathione disulfide/reduced glutathione ratio and cell peroxides; nimesulide triggered MPT, ATP depletion, high cell calcium, and caused mostly necrosis, with rare apoptotic cells. Coincubation with either cyclosporin A (an MPT inhibitor) or the combination of fructose-1,6-diphosphate (a glycolysis substrate) and oligomycin (an ATPase inhibitor) prevented the decrease in DeltaPsim, ATP depletion, and cell death. A physiological concentration of albumin abolished the effects of nimesulide on isolated mitochondria or HUH-7 cells. In conclusion, the weak acid, nimesulide, uncouples mitochondria and triggers MPT and ATP depletion in isolated mitochondria or hepatoma cells incubated without albumin. However, in the presence of albumin, only a fraction of the drug enters cells or organelles, and uncoupling and toxicity are not observed.     

Diglycolic acid,the toxic metabolite of diethylene glycol,chelates calcium and produces renal mitochondrial dysfunction in vitro

Context: Diethylene glycol (DEG) has caused many cases of acute kidney injury and deaths worldwide. Diglycolic acid (DGA) is the metabolite responsible for the renal toxicity, but its toxic mechanism remains unclear. Objective: To characterize the mitochondrial dysfunction produced from DGA by examining several mitochondrial processes potentially contributing to renal cell toxicity. Materials and methods: The effect of DGA on mitochondrial membrane potential was examined in normal human proximal tubule (HPT) cells. Isolated rat kidney mitochondria were used to assess the effects of DGA on mitochondrial function, including respiratory parameters (States 3 and 4), electron transport chain complex activities and calcium-induced opening of the mitochondrial permeability transition pore. DGA was compared with ethylene glycol tetraacetic acid (EGTA) to determine calcium chelating ability. DGA cytotoxicity was assessed using lactate dehydrogenase leakage from cultured proximal tubule cells. Results: DGA decreased the mitochondrial membrane potential in HPT cells. In rat kidney mitochondria, DGA decreased State 3 respiration, but did not affect State 4 respiration or the ADP/O ratio. DGA reduced glutamate/malate respiration at lower DGA concentrations (0.5?mmol/L) than succinate respiration (100?mmol/L). DGA inhibited Complex II activity without altering Complex I, III or IV activities. DGA blocked calcium-induced mitochondrial swelling, indicating inhibition of the calcium-dependent mitochondrial permeability transition. DGA and EGTA reduced the free calcium concentration in solution in an equimolar manner. DGA toxicity and mitochondrial dysfunction occurred as similar concentrations. Discussion: DGA inhibited mitochondrial respiration, but without uncoupling oxidative phosphorylation. The more potent effect of DGA on glutamate/malate respiration and the inhibition of mitochondrial swelling was likely due to its chelation of calcium. Conclusion: These results indicate that DGA produces mitochondrial dysfunction by chelating calcium to decrease the availability of substrates and of reducing equivalents to access Complex I and by inhibiting Complex II activity at higher concentrations.     

Morphometric studies in triacetyloleandomycin-induced ultrastructural modifications of rat hepatocyte mitochondria.

Morphometric parameters of mitochondria such as volumetric density, surface density of envelopes and cristae and numerical density were calculated for control untreated and triacetyloleandomycin (TAO)-treated rat hepatocytes using a point-counting technique. Moreover, morphometric parameters calculated experimentally and those computed on the basis of the least square interpolation and the agreement with the chi2 test, were compared. The equations modelling each main morphometric parameter of experimental motochondria were also computed. Morphometric study revealed that TAO produces a highly reproducible pattern of morphological alterations in the mitochondrial population of rat hepatocytes, and a good agreement between experimental and theoretical data was found. The response of hepatocyte mitochondria to TAO may be modelled by parabolic functions described by equations of the second degree. During the whole experimental period, the number of mitochondria decreases, but the specific volume of mitochondria increases. The area of the cristae surface per mitochondrion does not change substantially during the whole experimental period but since the quantity of internal mitochondrial membranes per hepatocyte is less in the later experimental period than in control material, it can be assumed that the oxidizing capacity per hepatocyte has diminished. The morphometric model based on TAO-treated hepatocyte mitochondria is different from those so far described in the literature for rat liver.     

Mitochondrial N-formylmethionyl proteins as chemoattractants for neutrophils

Mitochondria synthesize several hydrophobic proteins. Like bacteria, mitochondria initiate protein synthesis with an N-formylmethionine residue. Because N-formylmethionyl peptides have been found to be chemotactic for polymorphonuclear leukocytes (PMN), mitochondria isolated from cultured human cells and purified bovine mitochondrial proteins were tested for PMN chemotactic activity in vitro. Nondisrupted mitochondria were not chemotactic. However, intact mitochondria that had been incubated with a lysosomal lysate did stimulate PMN migration. Antibodies directed against two mitochondrial enzymes, cytochrome oxidase and ATPase, (both of which contain mitochondrially synthesized subunits) but not anti-C3 or anti-C5 decreased mitochondrially derived chemotactic activity. In addition, purified bovine mitochondrial N-formylmethionyl proteins stimulated PMN migration in vitro, whereas nonformylated mitochondrial proteins did not. Furthermore, the chemotactic activity of purified mitochondrial proteins and disrupted mitochondria was decreased by the formyl peptide antagonist butyloxycarbonyl-phenylalanine-leucine-phenylalanine-leucine-phenylalanine. Finally, disrupted mitochondria and purified mitochondrial proteins stimulated PMN-directed migration (chemotaxis), according to accepted criteria. In addition to other chemotactic factors, release of N-formylmethionyl proteins from mitochondria at sites of tissue damage, may play a role in the accumulation of inflammatory cells at these sites.     

Impaired uptake of glutathione by hepatic mitochondria from chronic ethanol-fed rats. Tracer kinetic studies in vitro and in vivo and susceptibility to oxidant stress.

Isolated hepatocytes incubated with [35S]-methionine were examined for the time-dependent accumulation of [35S]-glutathione (GSH) in cytosol and mitochondria, the latter confirmed by density gradient purification. In GSH-depleted and -repleted hepatocytes, the increase of specific activity of mitochondrial GSH lagged behind cytosol, reaching nearly the same specific activity by 1-2 h. However, in hepatocytes from ethanol-fed rats, the rate of increase of total GSH specific radioactivity in mitochondria was markedly suppressed. In in vivo steady-state experiments, the mass transport of GSH from cytosol to mitochondria and vice versa was 18 nmol/min per g liver, indicating that the half-life of mitochondrial GSH was approximately 18 min in controls. The fractional transport rate of GSH from cytosol to mitochondria, but not mitochondria to cytosol, was significantly reduced in the livers of ethanol-fed rats. Thus, ethanol-fed rats exhibit a decreased mitochondrial GSH pool size due to an impaired entry of cytosol GSH into mitochondria. Hepatocytes from ethanol-fed rats exhibited a greater susceptibility to the oxidant stress-induced cell death from tert-butylhydroperoxide. Incubation with glutathione monoethyl ester normalized the mitochondrial GSH and protected against the increased susceptibility to t-butylhydroperoxide, which was directly related to the lowered mitochondrial GSH pool size in ethanol-fed cells.     

Effect of thyroidectomy upon the activity of three mitochondrial shuttles in rats

The activities of mitochondrial alpha-glycerophosphate, malate-asparte, and malate-citrate shuttles which oxidize NADH were determined in liver and kidney cortex mitochondria isolated from Tx and control rats. Weight gain, relative liver and kidney size, oxygen consumption, and serum thyroxine were also determined. Tx animals weighed less, had smaller livers and kidneys, and showed significantly lower oxygen consumption of the resting animal and a marked decrease in serum thyroxine levels. The activity of the three shuttles studies was significantly less in liver mitochondria from Tx animals, particularly when studied in the absence of added ADP. Thyroidectomy had less effect upon shuttle activity of mitochondria from the kidney cortex, with significant decrease in activity found only in the complete alpha-glycerophosphate shuttle and in the endogenous malate-aspartate and malate-citrate shuttles studied in the absence of ADP. Changes in shuttle activity caused by thyroid hormone are discussed in relation to other known metabolic effects of thyroxine, and the possible primary role of adenine nucleotide translocase activity in mediating other thyroxine-dependent metabolic changes is considered.     

Therapeutic Influence of Zinc and Ascorbic Acid Against Lead induced Biochemical Alterations

The influence of co-administration of zinc (10 mg/kg, intraperitoneal [ip]) and ascorbic acid (10, 20 and 30 mg/kg, ip) against lead (lead acetate; 35 mg/kg, ip for 3 days) induced biochemical alterations was studied in young albino rats. The results revealed significant fall in hemoglobin content, on the other hand significant raise in the activity of serum transaminases and serum alkaline phosphatase after lead administration. Significant increase in lipid peroxidation and decreased level of reduced glutathione in liver showed oxidative stress due to lead exposure. Total protein content in liver and kidney were diminished after lead exposure. Activity of acid phosphatase in liver and kidney and alkaline phosphatase in kidney was increased significantly. Zinc and ascorbic acid treatment showed moderate therapeutic efficacy when administered individually, whereas more pronounced protective effects were observed after combined therapy of zinc and different doses of ascorbic acid. The results thus, suggested that co-administration of zinc and ascorbic acid may be useful in restoration of lead induced biochemical alterations.