Whey proteins inhibit food intake and tend to improve oxidative balance in obese zucker rats.

BACKGROUND/AIMS: Whey proteins (WP), obtained from milk after casein precipitation, represent a heterogeneous group of proteins. WP are reported to inhibit food intake in diet-induced experimental obesity; WP have been proposed as adjuvant therapy in oxidative stress-correlated pathologies. This work evaluates the effects of WP in comparison with casein, as a source of alimentary proteins, on food intake, weight growth and some indexes of oxidative equilibrium in Zucker Rats, genetically prone to obesity. METHODS: We monitored food intake and weight of Zucker Rats during the experiment, and some markers of oxidative equilibrium. RESULTS: WP induced significant decrease of food intake in comparison to casein (WP 80.41 ± 1.069 ml/day; CAS: 88.95 ± 1.084 ml/day; p < 0.0005). Body weight growth was slightly reduced, and the difference was just significant (WP 128.2 ± 6.56 g/day; CAS 145.2 ± 3.29 g/day; p = 0.049), while plasma HNE level was significantly lower in WP than in CAS (WP 41.2 ± 6.3 vs CAS 69.61 ± 4.69 pmol/ml, p = 0.007). Mild amelioration of oxidative equilibrium was indicated by a slight increase of total glutathione both in the liver and in the blood and a significant decrease of plasma 4-hydroxynonenal in the group receiving WP. CONCLUSIONS: The effect of WP on food intake and weight growth in Zucker Rats is particularly noteworthy since the nature of their predisposition to obesity is genetic; the possible parallel amelioration of the oxidative balance may constitute a further advantage of WP since oxidative stress is believed to be interwoven to obesity, metabolic syndrome and their complications.

Mutual interaction between glycation and oxidation during non-enzymatic protein modification.

Aging pathogenesis involves non-enzymatic modifications of proteins; protein oxidation, glycation and their interactions have aroused a particular interest. Possible interrelations between oxidation and glycation have been evaluated in vitro: bovine serum albumin was oxidized by gamma-irradiation and then exposed to in vitro glycation. Fluorescence modifications induced by radiolytic oxidation and glycation were similar and tended to be additive. Both non-enzymatic processes provoked a loss of free sulfhydryl groups and a strong increment of protein carbonyl content: this supports that glycation can act through oxidative mechanisms. The observed rearrangement of amino groups after irradiation could predispose proteins to glycation attacks. Protein peroxides generated during irradiation appear able to give birth to further protein modifications leading to the generation of carbonyl groups and to interact with monosaccharides, probably stimulating their autoxidation and in turn glycative protein damage. Glycation increases the oxidation-mediated structural damage revealed by SDS-PAGE. Therefore our data support the hypothesis of mutual enhancement between oxidation and glycation of proteins and suggest possible molecular mechanisms of interactions.

Lipoperoxidation in hepatic subcellular compartments of diabetic rats.

It is known that an accumulation of lipoperoxidative aldehydes malondialdehyde (MDA) and 4-hydroxynonenal (HNE) takes place in liver mitochondria during aging. The existence and role of an increased extra- and intra-cellular oxidative stress in diabetes, an aging-accelerating disease, is currently under discussion. This report offers evidence that lipoperoxidative aldehydes accumulate in liver microsomes and mitochondria at a higher rate in spontaneously diabetic BB/WOR rats than in control non-diabetic animals (HNE content, diabetes vs. control: microsomes 80.6+/-19.9 vs. 25.75+/-3.6 pmol/mg prot, p = .024; mitochondria 77.4+/-15.4 vs. 26.5+/-3.5 pmol/mg prot, p = .0103). Liver subcellular fractions from diabetic rats, when exposed to the peroxidative stimulus ADP/Fe, developed more lipoperoxidative aldehydes than those from non diabetic rats (HNE amount, diabetes vs. control: microsomes 3.60+/-0.37 vs. 2.33+/-0.22 nmol/mg prot, p = .014; mitochondria 3.62+/-0.26 vs. 2.30+/-0.17 nmol/mg prot, p = .0009). Liver subcellular fractions of diabetic rats developed more fluorescent chromolipids related to HNE-phospholipid adducts, either after in vitro peroxidation (microsomes: p = .0045; mitochondria: p = .0023) or by exposure to exogenous HNE (microsomes: p = .049; mitochondria: p = .0338). This higher susceptibility of diabetic liver membranes to the non-enzymatic attack of HNE may be due to an altered phospholipid composition. Moreover, a decreased activity of the HNE-metabolizing systems can be involved: diabetic liver mitochondria and microsomes were unable to consume exogenous HNE at the same rate as non-diabetic membranes; the difference was already significant after 5' incubation (microsomes p<.001; mitochondria p<.001). These data show an increased oxidative stress inside the hepatocytes of diabetic rats; the impairment of the HNE-metabolizing systems can play a key role in the maintenance and propagation of the damage.

Mechanisms of inactivation of hepatocyte protein kinase C isoforms following acute ethanol treatment.

Acute ethanol exposure of rat isolated hepatocytes leads to a significant decrease (-30%) in cytosolic enzymatic activity of classic protein kinase C (PKC) isoforms, while immunoreactive protein level measured by Western Blot remains unaffected. The inactivation of classic cytosolic isoforms appears dependent on the modification of the enzyme function, probably due to ethanol metabolism. In fact, pretreatment with 4-methylpyrazole (4MP), an inhibitor of alcohol dehydrogenase, fully prevented such damage. After ethanol treatment, a decrease of about 40% in both enzymatic activity and immunoreactive protein level of novel PKC isoforms was evident both in the soluble and particulate fractions. Even if 4MP cell pre-treatment afforded protection in this case too, the inhibitory action of ethanol on novel PKC hepatocyte isoforms involves a proteolytic mechanism as shown by Western Blot analysis. The reproduction of PKC inactivation by ethanol in hepatocyte lysate excluded a role of peroxisomal hydrogen peroxide in the pathogenesis of the damage investigated. This damage was not reduced by addition of catalase to the lysate model system.

Glutathione depletion induces apoptosis of rat hepatocytes through activation of protein kinase C novel isoforms and dependent increase in AP-1 nuclear binding.

Treatment of isolated rat hepatocytes with the glutathione depleting agents L-buthionine-S,R-sulfoximine or diethylmaleate reproduced various cellular conditions of glutathione depletion, from moderate to severe, similar to those occurring in a wide spectrum of human liver diseases. To evaluate molecular changes and possible cellular dysfunction and damage consequent to a pathophysiologic level of GSH depletion, the effects of this condition on protein kinase C (PKC) isoforms were investigated, since these are involved in the intracellular specific regulatory processes and are potentially sensitive to redox changes. Moreover, a moderate perturbation of cellular redox state was found to activate novel PKC isoforms, and a clear relationship was shown between novel kinase activation and nuclear binding of the redox-sensitive transcription factor, activator protein-1 (AP-1). Apoptotic death of a significant number of cells, confirmed in terms of internucleosomal DNA fragmentation was a possible effect of these molecular reactions, and was triggered by a condition of glutathione depletion usually detected in human liver diseases. Finally, the inhibition of novel PKC enzymatic activity in cells co-treated with rottlerin, a selective novel kinase inhibitor, prevented glutathione-dependent novel PKC up-regulation, markedly moderated AP-1 activation, and protected cells against apoptotic death. Taken together, these findings indicate the existence of an apoptotic pathway dependent on glutathione depletion, which occurs through the up-regulation of novel PKCs and AP-1.

Induction of heme oxygenase 1 in liver of spontaneously diabetic rats.

It has been suggested that diabetes induces an increase in oxidative stress; the increased expression of heme-oxygenase 1 (HO-1) in liver is believed to be a sensitive marker of the stress response. The aim of this study was to examine whether diabetes is able to induce HO-1 expression in liver. The specific mRNA was amplified by RT/PCR and calibrated with amplified beta-actin mRNA. The mRNA HO-1 levels in the liver of spontaneously diabetic rats were increased by 1.8 fold compared with non diabetics; this supports the hypothesis of weak but significant oxidative damage due to chronic hyperglycaemia. This work represents the first in vivo study exploring the semi-quantitative expression of HO-1 in the liver of spontaneously diabetic rats.

Effects of vitamin E on dolichol content of rats acutely treated with 1,2-dichloroethane.

Previous investigations have demonstrated that 1,2-dichloroethane (DCE) poisoning affects dolichol (Dol) concentration in rat liver. Dol, a long-chain polyprenol, is considered an important membrane component: as dolichyl phosphate, it is rate limiting for the synthesis of glycoprotein; as free or fatty acid, it is highly concentrated in the Golgi apparatus (GA) where it can increase membrane fluidity and permeability, required glycoprotein maturation and secretion. DCE biotransformation may stimulate pro-oxidant events through hepatocellular glutathione depletion. Since the molecules of Dol are susceptible to oxidative degradation, the aim of this investigation is to verify whether vitamin E (vit. E) supplementation in rats is able to prevent Dol breakdown during acute DCE treatment. Before acute DCE administration (628 mg/kg body weight), a group of male Wistar rats were pretreated with vit. E (33 mg/kg body weight) for 3 days. High-performance liquid chromatography analysis has shown that within 5-60 min after DCE administration, the Dol concentration decreased in liver homogenate, cytosol, microsomes and GA. Particularly, 60 min after the treatment, Dol levels in the trans Golgi fraction were 71% lower than in controls. Rat pre-treatment with vit. E prevented the DCE-induced decrease in Dol concentrations of all liver fractions considered, in particular the reduction of total-Dol observed in the trans Golgi fraction 60 min after treatment was only 40%. These data suggest that hepatic metabolism of DCE is able to promote peroxidative attacks which lead to the degradation of Dol molecules. The pre-treatment of rats with vit. E results in a good, although not complete, prevention of total-Dol depletion after DCE poisoning.

Effects of 1,2-dichloroethane intoxication on dolichol levels and glycosyltransferase activities in rat liver microsomes and Golgi apparatus.

Rat intoxication with a single dose of 1,2-dichloroethane (DCE) (50 microliters/100 g b.w) is able to induce a significant modification of protein glycosylation in the liver endoplasmic reticulum and Golgi apparatus. HPLC analysis shows that within 5-60 min after DCE-intoxication, the levels of total dolichol, free dolichol and dolichyl phosphate strongly decreased in the microsomes and Golgi apparatus. Particularly in total microsomes, dolichyl phosphate, which is rate-limiting for the biosynthesis of the N-linked oligosaccharide chains, drops to values significantly lower than in the control group 15 min after DCE poisoning. In the Golgi apparatus, the total dolichol, essential to enhance the fluidity and permeability of these membranes, early and significantly decreases already 5 min after DCE poisoning. Moreover, in the Golgi apparatus galactosyl- and sialyltransferase activities, the main enzymatic activities of terminal protein glycosylation, are significantly reduced, as measured 15 min after DCE intoxication. These data suggest that the impairment of glycoprotein synthesis, maturation and secretion may be involved in the pathogenesis of liver injury induced by acute DCE-intoxication.

Carbon tetrachloride-induced inhibition of hepatocyte lipoprotein secretion: functional impairment of Golgi apparatus in the early phases of such injury.

Functional change of liver Golgi apparatus during carbon tetrachloride (CCl4) poisoning was demonstrated both in rat isolated hepatocytes and in the whole animal. The "in vitro" experimental model provided evidence of Golgi derangement early after giving the haloalkane. The "in vivo" analyses also showed that such an alteration involves both formative and secretory sides of the subcellular structure.

Ethanol-induced effects on expression level, activity, and distribution of protein kinase C isoforms in rat liver Golgi apparatus.

Acute ethanol administration induces significant modifications both in secretive and formative membranes of rat liver Golgi apparatus. The decrease in glycolipoprotein secretion and their retention into the hepatocyte contribute to the pathogenesis of alcohol-induced fatty liver. Molecular and cellular mechanisms behind the ethanol-induced injury of the liver secretory pathway are not yet completely defined. In this study on intact livers from ethanol-treated rats, the involvement of the Golgi compartment in the impairment of hepatic glycolipoprotein secretion has been correlated with changes in the expression level, subcellular distribution and enzymatic activity of protein kinase C (PKC) isoforms. Acute ethanol exposure determined a translocation of classic PKCs and delta isoform from the cytosol to cis and trans Golgi membranes, the site of glycolipoprotein retention in the hepatic cell. A marked stimulation of cytosolic epsilon PKC activity was observed throughout the period of treatment. The presence of activated PKC isozymes at the Golgi compartment of alcohol-treated rat livers may play a role in hepatic secretion and protein accumulation. Direct and indirect effects of ethanol consumption on PKC isozymes and Golgi function are discussed.

Damaging effects of advanced glycation end-products in the murine macrophage cell line J774A.1.

The interaction of reducing sugars, such as aldose, with proteins and the subsequent molecular rearrangements, produces irreversible advanced glycation end-products (AGEs), a heterogeneous class of non-enzymatic glycated proteins or lipids. AGEs form cross-links, trap macromolecules and release reactive oxygen intermediates. AGEs are linked to aging, and increase in several related diseases. The aim of this study was to assess, in a murine macrophage cell line, J774A.1, the effects of 48 h of exposure to glycated serum containing a known amount of pentosidine, a well-known AGE found in the plasma and tissues of diabetic and uremic subjects. Fetal bovine serum was incubated with ribose (50 mM) for 7 days at 37 degrees C to obtain about 10 nmol/ml of pentosidine. The cytotoxic parameters studied were cell morphology and viability by neutral red uptake, lactate dehydrogenase release and tetrazolium salt test. In the medium and in the intracellular compartment, bound and free pentosidine were evaluated by HPLC, as sensitive and specific glycative markers, and thiobarbituric acid reactive substances (TBARs), as index of the extent of lipid peroxidation. Our results confirm that macrophages are able to take up pentosidine. It is conceivable that bound pentosidine is degraded and free pentosidine is released inside the cell and then into the medium. The AGE increase in the medium was combined with an increase in TBARs, meaning that an oxidative stress occurred; marked cytotoxic effects were observed, and were followed by the release of free pentosidine and TBARs into the culture medium.

1,1,2,2-Tetrachloroethane-induced early decrease of dolichol levels in rat liver microsomes and Golgi apparatus.

Dolichols are long-chain polyprenols containing 14-22 isoprene units, present in mammalian tissues as free dolichol (Free-Dol), fatty acyl dolichyl esters (Dol-FA), and dolichyl phosphate (Dol-P). The hepatic level of Dol-P seems to be a rate-limiting factor for glycosylation processes. Previous studies from our laboratory demonstrated the susceptibility of the dolichol molecule to undergo radical attacks. Since the toxicity of 1,1,2,2-tetrachloroethane (TTCE)is dependent on the free-radical production during hepatic biotrasformation, it was of interest to determine whether this haloalkane might affect glycosylation mechanisms by changing dolichol levels and distribution in rat liver microsomes and Golgi apparatus (GA). Male Sprague-Dawley rats received a single dose of TTCE (574 mg/kg body weight) and were then sacrificed at different times (5, 15, 30, or 60 min). In the TTCE-treated rats both serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and hepatic triglycerides (TG) were significantly higher than control, while microsomal glucose 6-phosphatase (G6Pase) activity was decreased. In total microsomes Dol-P levels considered rate-limiting for the biosynthesis of the N-glycosylated proteins were significantly lower than in the control group 15 min after TTCE treatment. In normal rat liver, F1 secretory fraction of CA is 60-fold enriched in total dolichol content with respect to microsomes. In this compartment the total dolichol content, essential for the increase in membrane fluidity and permeability required for glycoprotein maturation and secretion, decreased significantly 5 min after TTCE treatment. Our results suggest that TTCE may affect dolichol functions in rat liver.

Impact of ischemia/reperfusion on transplanted livers procured from elderly cadaveric donors.

The increasing number of clinical indications for liver transplantation has forced physicians to use livers procured from elderly cadaveric donors to expand the graft pool. However, the degree of ischemia/reperfusion damage in elderly livers remains poorly investigated. In this study, the outcomes of livers procured from a group (I) of young donors (n=12; 38 +/- 12 years; range: 21-58) were compared with a group (II) from elderly donors (n=7; 68 +/- 7 years; range: 62-84) for changes in reduced glutathione, the main hepatic free radical scavenger. Reduced and oxidized glutathione were assayed by high performance liquid chromatography in liver biopsies performed just before cold ischemia and during early reperfusion. A significant decrease in reduced glutathione was observed at the time of reperfusion in both groups I (P=.0195) and II (P=.002). Before cold ischemia and during early reperfusion, no differences between young versus elderly donors were noted in the oxidized/reduced glutathione ratio, in conventional graft function markers or in liver-related hemostatic parameters. Comparable glutathione contents were measured at the time of early reperfusion in livers obtained from young and elderly cadaveric donors, suggesting that livers procured from elderly donors might be adequately protected against ischemia/reperfusion damage.

Orthotopic liver transplantation in a young adult (33 years old) using an 84-year-old donor.

Shortage of liver donors and the increasing number of patients on the waiting list for liver transplantation have led to a widening of the definition of liver donor suitability. Although the age limit for liver donors is controversial, current opinion is towards using liver allografts from donors older than 60 years. However, to date only a few cases that showed a good performance of liver graft by donors older than 60 years have been described. In this case report, orthotopic liver transplantation in a 33-year-old patient who received a graft from an 84-year-old donor is presented. A careful evaluation of the conventional donor-related risk factors (hemodynamics, hepatic function and histologic features) was carried out. Moreover, free radical scavenger glutathione was measured before cold ischemia and at the time of reperfusion in hepatic biopsies. After a 1-year follow-up, the recipient exhibits good general conditions and normal liver function values.

Study of proteins, phospholipids and cholesterol of rat bile during chronic drainage.

Glycerophospholipids, cholesterol and proteins of rat bile were analyzed at different time-intervals during the bile duct cannulation over a period of 24 hr, to study a possible association between the secretion of these bile components. Glycerophospholipids and cholesterol decreased between the 16th-24th hrs, then rose again, showing a bile acid synthesis dependence. In contrast, during the entire collection period, protein concentration was normal. On gel electrophoresis bile proteins give a spectrum of fifteen discrete bands, three of them being Sudan black positive. Some, but not all bile protein bands, show a pattern similar to serum proteins both by means of SDS disc electrophoresis and of immunological techniques. According to the bile composition in GPL and cholesterol and the presence in bile of lipoproteins with SDS electrophoresis migration superimposable to apo-A-IV of serum high density lipoproteins, the following hypothesis is suggested to explain the origin and pathway that some fractions of bile can follow to reach biliary canalicula: some serum or membrane components (that is GPL, cholesterol and possibly apo-A-IV) might insert themselves into the outer leaflet of hepatocyte plasmamembranes at the sinusoidal side; from here they may slip over the inner plasmamembrane monolayer, through the junctions, to the canalicular region of the membrane to give rise, by the action of bile salts, to micelles of bile, together with components coming from other subcellular compartments, following different pathways.

Effects of simvastatin on liver and plasma levels of cholesterol, dolichol and ubiquinol in hypercholesterolemic rats.

Increased levels of blood cholesterol are considered as a major factor in the development of atherosclerosis. Simvastatin, a drug which blocks hydroxymethylglutaryl coenzyme A reductase (HMGCoAR), reduces plasma cholesterol and increases HDL-cholesterol in rats fed a hypercholesterolemic diet. Moreover, simvastatin produces a significant decrease of ubiquinol and dolichol in plasma and in liver.

[Changes in lipoglycoprotein metabolism in toxic fatty liver]. / Alterazioni del metabolismo lipoglicoproteico nelle epatosteatosi tossiche.

BACKGROUND: A number of agents that produce liver injury also cause the accumulation of an abnormal amount of fat, predominantly triglycerides (TGs) in the parenchymal cells. Fatty liver (FL) is the result of an hepatocyte imbalance between the rate of synthesis and output of TGs into the plasma. TGs are not secreted as such, but combined with a glycoprotein moiety, and particularly with the very low density lipoproteins (VLDLs). This fraction is involved in the transport of hepatic TGs to extrahepatic tissues. FL can be induced by either acute or chronic administration of ethanol (EtOH), and/or several haloalkanes (carbon tetrachloride, CCl4; 1.2-dichloroethane, DCE; 1.1.2.2-tetrachloroethane, TTCE), both in laboratory animals and in man. Since the pathogenesis of this disease is a crucial problem, as yet undefined, the purpose of this article is to summarize the studies which have unraveled some of the mechanisms involved in FL, particularly the role played by impaired lipoglycoproteins (LGP) metabolism in rat liver. DISCUSSION: An important element in the pathogenesis of EtOH- and haloalkanes-induced FL is the impairment of hepatic secretion of VLDLs, which occurs soon after poisoning. Various steps of the secretory pathway are probably involved in the expression of such damage. The intoxication of rats with these xenobiotics leads to an early impairment of the hepatocyte system responsible for terminal glycosylation and maturation of LGP at the level of three different subfractions (F1, F2 and F3) of purified Golgi apparatus (GA). The earliest functional change is a block of LGP transit through the GA cisternae and vesicles, both in isolated hepatocyte model and in the whole animal. The glycosylation of LGP is a multistep process which starts in the rough endoplasmic reticulum (RER), and comes to its end in the GA. Dolichols (Dol) are a family of long-chain polyisoprenoid alcohols, present either as neutral free-Dol and dolichyl-phosphate (Dol-P). The latter acts as a glycosyl carrier across the RER membranes in the initial steps of LGP biosynthesis. Nearly all the other reactions occur in GA, where free-Dol have a role either in terminal LGP processing or in their secretion into the blood stream. Several investigations indicated that both EtOH and haloalkanes (CCl4, DCE, and TTCE) may selectively and precociously impair the total microsomes (TM) and GA pool of Dol, particularly in F1. Lipid peroxidation appears to be the fundamental mechanism involved. CONCLUSIONS: Such results, obtained in several works, point out a key role played in FL by selective impairment of MT and GA processes which provide for the synthesis, maturation and release of hepatic LGP.

[CoQ10 blood levels and erythrocyte concentration of GSH in ischemic heart patients during exercise test (effects of vitamin E)]. / Comportamento della concentrazione plasmatica di CoQ10 ed eritrocitaria di GSH in cardiopatici ischemici sottoposti a test ergometrico (effetti indotti dall'assunzione di vitamina E).

During exercise there is an increase of oxygen consumption with production of superoxide anion. Tocopherols and ubiquinones are intrinsic lipid components involved in antioxidant protection and also glutathione reduced is an important water soluble antioxidant. The authors take into consideration 28 patients with ischemic heart disease coming in a rehabilitation center. In a group of 14 of them we studied the effects on the exercise ergonometer test of administration of 1200 mg of tocopherol on the behaviour of ubiquinone plasmatic levels and GSH. In this group CoQ10 after exercise increase significantly (0.762 SD 0.134 g/ml before vs 0.827 SD 0.89 after). GSH doesn't increase after (2.5 SD 0.459 mM/l vs 2.492 SD 0.457). In the group of patients without tocopherol after exercise CoQ10 decrease significantly (-39%) and also GSH has the same behaviour (-15%). Our study shows that the administration of tocopherol prevents lipoperoxidation occurring during exercise test.

[Toxicity of 4-chloro-2-nitroaniline and 2-chloro-4-nitroaniline to isolated rat hepatocytes]. / Tossicità della 4-cloro-2-nitroanilina e della 2-cloro-4-nitroanilina su epatociti isolati di ratto.

The toxicity of 4-chloro-2-nitroaniline (4C2NA) and 2-chloro-4-nitroaniline (2C4NA) was investigated on isolated rat hepatocytes following 1-3 hours of exposure to 0.2 and/or 2 mM of these xenobiotics. The higher of the two concentrations appeared to induce a statistically significant loss of cellular viability (p less than 0.01 compared to control), judged by Trypan Blue staining, after 3 hours of incubation with these substances means = 58, SD = 7%; and means = SD = 7%; for 4C2NA and 2C4NA, respectively). Furthermore, both chloronitroanilines produced an hepatocellular and microsomal damage demonstrated by conspicuous changes in LDH and G-6-Pase activities (p less than 0.01). The exposure to 2 mM of both 4C2NA and/or 2C4NA produced a marked depletion of the intracellular pool of GSH after 3 hours (13 mM/10(6) and 10 mM/10(6) cells, respectively; p less than 0.01). Thus it seems possible that 2C4NA may induce a more severe cellular damage than that induced by 4C2NA.

Biochemical and morphologic effects after extended liver resection in rats: preliminary results.

After hepatic resection and transplantation with a partial graft, death and regeneration of the hepatocytes coexist in the liver. However, when the functional liver mass is inadequate to ensure a proper balance between regeneration vs functional and metabolic demands, small-for-size syndrome develops. We assessed the early effects of extended hepatic resection on liver function in a rat model. Six male Sprague-Dawley rats underwent 80% resection of the liver, and 6 rats served as a control group. At 6 hours after resection, blood samples were obtained from the hepatic vein for measurement of reduced glutathione (GSH), oxidized glutathione (GSSG), and hepatic venous oxygen saturation (Shvo(2)), and for standard liver function tests including determination of concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase, and total bilirubin. The remnant lobe was removed for GSH assay and histopathologic analysis. In the resection group, values were significantly higher for ALT (P = .002), AST (P = .002), and Shvo(2) (P = .01), whereas a significant decrease was observed for blood GSH (P = .009) but not liver GSH. Also in the resection group, we observed characteristic hepatocyte vacuolization with a gradient from periportal acinar zone 1 to the centrolobular area, the presence of hemorrhagic necrosis, and several leukocyte adhesions. The Shvo(2) and GSH data suggest early alteration of oxygen metabolism, as demonstrated by the reduction in oxygen uptake and decreased liver GSH secretion, with preservation of hepatic GSH. Mitochondrial dysfunction and oxidative injury seem to have a crucial role in early onset of liver damage.