Wheat bran protects Fischer-344 rats from diquat-induced oxidative stress by activating antioxidant system: selenium as an antioxidant

Wheat bran had a protective effect against diquat toxicity in rats fed a purified diet (PD). We studied the effects of wheat bran on the antioxidant system in the liver of rats treated with saline and diquat. Although feeding wheat bran did not affect the concentration of hepatic non-protein sulfhydryl or the activity of glucose 6-phosphate dehydrogenase in the saline-injected rats, these values were significantly higher in the rats fed PD containing wheat bran (W-PD) than in rats fed only PD after administering diquat. The glutathione peroxidase and reductase activities were significantly elevated by wheat bran in the saline-injected rats. Although the glutathione peroxidase activity was unchanged in both the PD-fed rats and W-PD-fed rats after the diquat treatment, the glutathione reductase activity was significantly decreased in both the PD-fed and W-PD-fed rats. Feeding the rats with PD containing 0.15 ppm selenium as well as with W-PD elevated the activity of hepatic glutathione peroxidase and attenuated the diquat toxicity. These results indicate that wheat bran protected against diquat toxicity by activating the hepatic antioxidant system, and that selenium was the key antioxidant in wheat bran.     

Relationship between body iron stores and diquat toxicity in male Fischer-344 rats

The effects of body iron stores on diquat (DQ)-induced toxicity were examined in male Fischer-344 rats, which are sensitive to this herbicide. The rats (5 weeks old) were fed diets containing 40 (lower iron storage [LIS] group) or 320 ppm iron (higher iron storage [HIS] group) for 5 weeks. The concentrations of nonheme iron and ferritin in the liver and kidney were significantly higher in the HIS group than in the LIS group (P<0.0001), although there was no significant differences between the HIS and LIS groups in hematological parameters, including red blood cell count, hemoglobin concentration, and mean corpuscular volume. Three hours after administration of 0.1 mmol DQ/kg, serum alanine aminotransferase and urea nitrogen were significantly higher than in controls (saline injection) for both the LIS and HIS groups (P<0.01), and, after DQ injection, these parameters were significantly higher in the HIS group than in the LIS group (P<0.01). When the rats were injected with 0.075 or 0.1 mmol DQ/kg, the survival time was significantly shorter in the HIS group than in the LIS group (P<0.05). These findings suggest that higher body iron stores result in more severe DQ toxicity in Fischer-344 rats.     

Influence of age and exercise training on lipid metabolism in Fischer-344 rats

The influence of training on fatty acid and glyceride synthesis by liver and adipose tissue homogenates of young and old Fischer-344 rats was examined. Four groups of rats (10 animals/group) were studied: young untrained, young trained, old untrained, and old trained. Training of each group was for 10 wk at 75% maximal O2 uptake. Young rats were killed at 6 mo of age and old rats were killed at 27 mo of age. Fatty acid synthesis was assessed by measuring the activities of acetyl-CoA carboxylase, fatty acid synthase, ATP citrate-lyase, "malic" enzyme, and glucose-6-phosphate dehydrogenase. Glyceride synthesis was evaluated by determining the rate of incorporation of [14C]glycerol 3-phosphate into lipids. In addition, lipoprotein lipase activity was measured in acetone-ether powders of adipose tissue from the four groups of rats. In liver, training had no effect on fatty acid or glyceride synthesis in either group. However, aging caused a significant decrease in the activities of four of the lipogenic enzymes but had no effect on glyceride synthesis. Training caused an increase in fatty acid synthase and glyceride synthesis in adipose tissue, and aging decreased lipoprotein lipase activity. It was concluded that training enhances the synthetic capacity of lipids by adipose tissue but that aging had a more profound effect in that the activities of the enzymes involved in these processes were lower in the old rats. Furthermore, the decreased activity of lipoprotein lipase in the older rats may explain the higher plasma triglyceride levels that were observed in these animals.     

Protective effects of wheat bran against diquat toxicity in male Fischer-344 rats

After injection with 0.1 mmol diquat/kg body weight, survival time was markedly shorter in Fischer-344 rats fed a purified diet than in rats fed a regular diet, and much more severe hepatotoxicity and nephrotoxicity were observed in the former than in the latter. The longer the feeding period on the purified diet, the shorter the survival time after diquat administration. These results indicate that the purified diet lacked components present in the regular diet that had protective effects against diquat toxicity. These two diets had nearly the same composition and content of vitamins and minerals. We tested the ingredients of the regular diet to determine which ones reduce diquat toxicity. We found that wheat bran had a protective effect, but that rice bran and bean-curd refuse (okara) did not.     

Catecholamine-synthesizing enzymes in paraganglia of aged Fischer-344 rats

Summary The catecholamine-synthesizing enzymes, tyrosine hydroxylase, dopamine--hydroxylase and phenylethanolamine-N-methyltransferase were examined by immunohistochemistry in hypertrophied paraganglia of aged male Fischer-344 rats. All paraganglionic cells reacted with antibodies against tyrosine hydroxylase. Dopamine -hydroxylase was identified in most paraganglionic cells, indicating that they synthesized norepinephrine. A variable number of paraganglia were positive for phenylethanolamine-N-methyltransferase, which suggested that they synthesized epinephrine. The formaldehyde-induced fluorescence method demonstrated greenish-yellow fluorescence or yellowish-brown fluorescence. The intensity of the fluorescence was in the same range as in adrenal medullary cells. The observations indicate that paraganglia are capable of synthesizing epinephrine.Dr. J.M. Stolk is the recipient of RSDA K2-00018 from the National Institute of Health.     

Hepatic macromolecular covalent binding of mononitrotoluenes in Fischer-344 rats

The mononitrotoluenes are important industrial chemicals which display isomeric specificity in their ability to induce hepatic DNA excision repair in Fischer-344 rats. Covalent binding of the structurally related hepatocarcinogen, 2,6-dinitrotoluene, to hepatic DNA is markedly decreased by prior administration of the sulfotransferase inhibitors pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP). The objectives of this study were to determine whether hepatic macromolecular covalent binding of the mononitrotoluene isomers differed and to determine whether covalent binding of the mononitrotoluenes to hepatic DNA in vivo was decreased by inhibitors of sulfotransferase. Male Fischer-344 rats were given a single oral dose of [ring-U-14C]-2-, 3- or 4-nitrotoluene (2-, 3- or 4-NT) and killed at various times thereafter. Livers were removed and analyzed for total and covalently bound radiolabel. Maximal concentrations of total radiolabel were observed between 3 and 12 h after the dose, and there were no large differences among the 3 isomers in peak concentrations achieved. Covalent binding to hepatic macromolecules was maximal 12 h after administration for all three isomers. Thereafter, concentrations of covalently bound 2-NT-derived material were always 2-6 times higher than those of 3- or 4-NT-derived material. When DNA was isolated from livers of rats given the mononitrotoluenes 12 h previously, only 2-NT was observed to covalently bind at concentrations above the limits of detection of the assay. The covalent binding of 2-NT, but not that of 3- or 4-NT, to both total hepatic macromolecules and DNA was markedly decreased by prior administration of either PCP or DCNP. Covalent binding to hepatic DNA was decreased by greater than 96%. The results of this study correlate well with studies which have demonstrated that 2-NT, but not 3- or 4-NT, induces DNA excision repair. Furthermore, they suggest that 2-NT, like the hepatocarcinogen 2,6-dinitrotoluene, requires the action of sulfotransferase for its conversion to a species capable of covalently binding to hepatic DNA.     

Amiloride does not alter NaCl avoidance in Fischer-344 rats

Fischer-344 (F-344) rats differ from other common rat strains in that they fail to show any preference for NaCl at any concentration in two- bottle preference tests. Because 100 microM amiloride partially blocks the NaCl-evoked chorda tympani (CT) response in electrophysiological studies, we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without 100 microM amiloride solution as the solvent. A third group was tested with unadulterated NaCl solutions following CT transection. Amiloride had no significant effect on the NaCl preference-aversion function, whereas CT transection significantly reduced NaCl avoidance. These results suggest that the amiloride-sensitive component of the NaCl response is not necessary for F-344 rats to display avoidance of NaCl, but the entire CT input is.      

Age-related alterations of enzyme activities and subunits of hepatic glutathione S-transferases in male and female Fischer-344 rats

Enzyme activities of glutathione S-transferases (GSTs) toward five different substrates (benzalacetone (PBO), styrene oxide (STOX), sulfobromophthalein (BSP), 1,2-dichloro-4-nitrobenzene (DCNB) and 1-chloro-2,4-dinitrobenzene (CDNB)) as well as concentrations of four subunits of GST isozymes (1, 2, 3 and 4) were determined using cytosol fractions obtained from livers of young (6 months) and old (26 months) Fischer-344 rats of both sexes. Values for enzyme activities for three substrates (DCNB, BSP and PBO) in young male rats were significantly higher than the corresponding values in female rats. In old male rats, values were generally lower than the corresponding values in young male rats, becoming close to corresponding values in young female rats. Old female rats, however, exhibited values close to those in young female rats, except for DCNB and STOX values, which were slightly lower in old female rats. GST subunits 3 and 4, as determined by high-performance liquid chromatography after purification by affinity chromatography using S-hexyl-glutathione, were predominant in young males, whereas concentrations of subunits 1 and 2 were higher in females than in males. In male rat livers, concentrations of subunits 3 and 4 decreased considerably with age while those of subunits 1 and 2 increased, so that the subunit pattern in old male rats tended to be similar to that of young female rats. In old females, a decrease in the concentration of subunits 3 and 4 and an increase in the concentration of subunit 1 were also observed as in old male rats, while the subunit 2 concentration tended to decline. Furthermore, the elution pattern of affinity chromatography changed with age, yielding an earlier elution of most subunits in old male rats and of subunit 1 in old female rats. The results suggest that age-related changes that occur with GSTs in livers of male rats are essentially a feminization of the isozyme pattern. However, despite rather unremarkable changes in enzyme activities with age in females, considerable changes of subunit pattern (a general decrease in concentration of subunits 2, 3 and 4 and an increase in the concentration of subunit 1) were also observed in female rats, and these were much greater than could be predicted from enzyme activity changes with age in this sex.     

Organ blood flow in Fischer-344 rats bearing MCA-induced sarcoma.

Although blood flow is central to systemic metabolism, little is known about the effect of tumor on the perfusion of host tissues. This study evaluated the effects of a methylcholanthrene-induced sarcoma on blood flow to intra-abdominal organs and skeletal muscle of Fischer-344 rats anesthetized with pentobarbital sodium. Animals were studied by aortic injection of radiolabeled microspheres when the tumors reached 20% of body weight. Total-organ arterial flows in spleen, liver, small intestine, and pancreas were each increased to 50-150% in tumor bearers relative to controls (P less than 0.05). Portal venous flow and flow per gram to hindlimb muscle were 60 +/- 20 and 300 +/- 100% greater, respectively, in tumor-bearing animals (P less than 0.005). This study shows that tumor growth can be associated with large changes in organ flow and distribution of cardiac output. The increase in skeletal muscle flow in the tumor bearers, which lost normal tissue weight relative to pair-fed controls (P less than 0.05), is in marked contrast to decreased muscle flow previously observed in simple starvation.     

Ocular and regional cerebral blood flow in aging Fischer-344 rats

Vascularremodeling and changes in vascular responsiveness occur in the ratcerebrum with old age. This includes reductions in cerebral arteriolarnumerical density, cross-sectional area, distensibility, the relativeproportion of distensible elements in the cerebral arteriolar wall, andreduced endothelium-dependent relaxation. The purpose of this study wasto test the hypothesis that old age results in an increase in vascularresistance and, correspondingly, a decrease in blood flow to ocular,regional cerebral, and spinal tissue in the rat. Blood flow wasmeasured in the eye, olfactory bulb, left and right cerebrum, pituitary gland, midbrain, pons, cerebellum, medulla, and spinal cord of juvenile(2-mo-old, n = 6), adult (6-mo-old,n = 7), and aged (24-mo-old,n = 7) male Fischer-344 rats. Arterialpressure and blood flow were used to calculate vascular resistance.Vascular resistance in the eye of aged rats (6.03 ± 1.08 mmHg · ml¹ · min · 100 g) was higher than that in juvenile (3.83 ± 0.38 mmHg · ml¹ · min · 100 g) and adult rats (3.12 ± 0.24 mmHg · ml¹ · min · 100 g). Similarly, resistance in the pons of older rats (2.24 ± 0.55 mmHg · ml¹ · min · 100 g) was greater than in juvenile (0.66 ± 0.06 mmHg ·ml¹ · min · 100 g) and adult rats (0.80 ± 0.11 mmHg · ml¹ · min · 100 g). In contrast, vascular resistance in the pituitary gland was lowerin the aged rats (juvenile, 3.09 ± 0.22; adult, 2.79 ± 0.42;aged, 1.73 ± 0.32 mmHg · ml¹ · min · 100 g, respectively). Vascular resistance was not different in othercerebral tissues or in the spinal cord in the aged rats. These datasuggest that regional cerebral and spinal blood flow and vascularresistance remain largely unchanged in conscious aged rats at rest butthat elevations in ocular vascular resistance and, correspondingly,decreases in ocular perfusion with advanced age could have seriousadverse effects on visual function.

     

Attenuated hippocampus-dependent learning and memory decline in transgenic TgAPPswe Fischer-344 rats

Alzheimer's disease (AD) is characterized by increased beta amyloid (Abeta) levels, extracellular Abeta deposits in senile plaques, neurofibrillary tangles, and neuronal loss. However, the physiological role of normal levels of Abeta and its parent protein, the amyloid precursor protein (APP) are unknown. Here we report that low-level transgenic (Tg) expression of the Swedish APP mutant gene (APPswe) in Fischer-344 rats results in attenuated age-dependent cognitive performance decline in 2 hippocampus-dependent learning and memory tasks compared with age-matched nontransgenic Fischer-344 controls. TgAPPswe rats exhibit mild increases in brain APP mRNA (56.8%), Abeta-42 (21%), and Abeta-40 (6.1%) peptide levels at 12 mo of age, with no extracellular Abeta deposits or senile plaques at 6, 12, and 18 mo of age, whereas 3- to 6-fold increases in Abeta levels are detected in plaque-positive human AD patients and transgenic mouse models. The data support the hypothesis that a threshold paradigm underlies Abeta-related pathology, below which APP expression may play a physiological role in specific hippocampus-dependent tasks, most likely related to its neurotrophic role.     

Effect of BCNU pretreatment on diquat-induced oxidant stress and hepatotoxicity

Diquat administration produces hepatic necrosis in male Fischer-344 rats, and minimally in male Sprague-Dawley rats, with massive oxidant stress observable in both strains as evidenced by increased biliary efflux of glutathione disulfide (GSSG). Pretreatment of both strains of rats with 80 mg/kg of 1,3-bis(2-chloroethyl)-N-nitrosourea (BCNU) inhibited hepatic glutathione reductase by 75 percent and increased dramatically the biliary efflux of GSSG produced by administration of diquat. BCNU pretreatment markedly potentiated diquat hepatotoxicity in the Fischer rats and modestly in Sprague-Dawley rats. BCNU-pretreated Fischer rats did not show an enhanced depletion of nonprotein sulfhydryls in response to diquat, in spite of the dramatic potentiation of the hepatic necrosis produced, nor were protein thiols depleted. The effects of BCNU on diquat hepatotoxicity in the Fischer rat are consistent with a critical role for reactive oxygen species in the pathogenesis of the observed hepatic necrosis and for the protective role of the glutathione peroxidase/reductase system. The data suggest that shifts in thiol-disulfide equilibria are not responsible for the cell death produced by oxidant stress in vivo, but are consistent with a role for lipid peroxidation in the pathogenesis of the lesion.     

Effect of oxidative stress on rat thyrocyte iodide metabolism

Thyroid cells fall into the type of cells functioning during continuous production of high H(2)O(2) concentrations. We studied the effect of H(2)O(2)-induced oxidative stress (0.1, 1.0 and 10.0 mM) on the activities of the key steps of iodide metabolism (uptake, oxidation and organification) in thyrocytes cultivated in an organ culture. After 60 min cultivation of cells in a medium containing H(2)O(2) at concentrations of 1.0 and 10.0 mM iodide (I(-)) uptake, thyroperoxidase (TPO) activity and I(-) organification were completely inhibited. No restoration of the parameters studied was observed within the subsequent 24 h of cultivation. The inhibitory effect of 0.1 mM H(2)O(2) was reversible. Activation of I(-) uptake in the cultivated tissue and a 520-880% increase of the total I(-) content were observed after 8 and 24 h. The concentration of I(-) protein-bound fraction was raised by 220% after 24 h. A biphasic effect of 0.1 mM H(2)O(2) on TPO was observed: 76.2% and 72.2% inhibitions were seen after 2 and 8 h, respectively, whereas 40.0% enzyme activation was after 5 h. TPO activity was partially restored after 24 h and amounted to 65% of the initial value. The significant increase in the concentration of iodide protein-bound fraction, which was observed simultaneously with TPO inhibition, could be due to thyroglobulin non-enzymic iodination under H(2)O(2)-generated oxidative stress. The data obtained indicate that iodide oxidation, as a step in the biosynthesis of thyroid hormones, was most sensitive to oxidative stress activation. The impaired iodide uptake and its organification during oxidative stress can play a pathogenetic role in disturbed functions of thyroid cells.     

Metabolic adaptations to arsenic-induced oxidative stress in male wistar rats

The present study was planned to investigate the effect of arsenic in rats on several biochemical indices of oxidative stress. Rats were exposed to arsenite in drinking water for upto 12 weeks. Chronic exposure to arsenic for a period of 12 weeks significantly (p < 0.05) increased arsenic burden in blood, liver, and kidney. Several intrinsic antioxidant defenses were activated after a 4-week exposure to arsenic. Some remained elevated, but others became depressed over a longer exposure period. Alterations in most of the biochemical variables reached statistical significant (p < 0.05). Arsenic significantly (p < 0.01) reduced mRNA expression of the superoxide dismutase 2 (SOD2) gene with respect to the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene. These observations indicated that prolong exposure to arsenic causes induction of oxidative stress and biochemical alterations.     

Behavioral and electrophysiological responses to NaCl in young and old Fischer-344 rats

This study compared both behavioral and electrophysiologicalresponses to NaCl in young and old Fischer-344 rats. These comparisonswere made in the same individuals. Preference for NaCl solutionsversus water was assessed using two-bottle preference tests.The integrated response of the chorda tympani nerve to NaClwas recorded. NaCl neural-response magnitude and correspondingbehavioral sensitivity appear to decrease with age in the Fischer-344rat at concentrations > 0.15 M and neural-response magnitudesincrease at lower concentrations.     

Lack of effect of chronic nicotine administration on fatty acid distribution in the liver, testis, and adipose tissue of male Fischer-344 rats

A comparison is made of the percentage compositions of major fatty acids in liver and testis phospholipids, liver and abdominal adipose tissue triglycerides, and liver sterol esters in male Fischer-344 rats administered a physiological saline control or a "smoking" dose of nicotine (1000 micro g base/kg/day, subcutaneously) for 2 or 22 months. Results indicate that there is no major trend, or significant difference, between nicotine- or saline-treated rats with respect to major fatty acid distribution. Some differences in fatty acid distribution in the various lipid fractions were found between young and old rats.     

Knockout of cellular glutathione peroxidase gene renders mice susceptible to diquat-induced oxidative stress.

Two experiments were conducted to determine the protection and the underlying mechanisms of cellular glutathione peroxidase (GPX1) against lethal, acute oxidative stress induced by an intraperitoneal injection of 24 mg diquat/kg body weight. In experiment 1, mortality and survival times were compared among selenium (Se)-adequate or deficient GPX1 knockout mice [GPX1(-/-)] and wild-type mice (WT). In experiment 2, mice from these four groups were euthanized at 0, 1, 2, and 3 h after the injection of diquat to elucidate the time course of oxidative events. The stress produced 100% mortality in all of the groups except for the Se-adequate WT, which were euthanized on day 7 for analysis. The Se-deficient WT and the Se-adequate GPX1(-/-) had similar survival times (4.1 and 3.9 h), which were longer (p < .05) than that of the Se-deficient GPX1(-/-) (2.4 h). However, these three GPX1-deficient groups had higher levels (p < .05) of hepatic F2-isoprostanes and carbonyl contents and/or plasma alanine aminotransferase activities than those of the Se-adequate WT. The diquat-induced formations of hepatic F2-isoprostanes in these animals peaked at 1 h and preceded the rise of plasma alanine aminotransferase in the Se-adequate GPX1(-/-). Responses of hepatic superoxide dismutase activities to the diquat treatment were affected by the GPX1 level. In conclusion, GPX1 is the major selenoprotein to protect mice against the lethal oxidative stress induced by diquat.     

Escherichia coli K12 does not colonize the gastrointestinal tract of Fischer-344 rats

Summary The colonizing potential ofEscherichia coli K12 containing a vector coding for somidobove (bovine somatotropin) was determined. Treated male and female Fischer-344 rats were given a single oral gavage inoculum of sucrose with/without tetracycline (15 g/ml). Untreated control animals received similar drinking water regimes. All animals survived until termination. There were no clinical signs of toxicity observed and no treatment-related effect upon body weight, food consumption, or efficiency of food utilization. Fresh fecal samples were collected from each rat every 24 h following inoculation and the population of the marked strain was quantitated until no bacterial colonies were observed for two consecutive days. While all inoculated rats were positive at 24 h, by 72 and 96 h all had become negative for the test (marked) strain, as were the corresponding control group throughout the test. The frozen stock of the marked strain used as the positive control demonstrated that the agar plates were selective for the test strain. Fourteen days following inoculation, all groups of rats were killed and the gastrointestinal tracts removed and treated to recover the marked strain. There was no evidence of the marked strain in the gastrointestinal tract of any rat from any group. Thus, theE. coli K12 host/vector system used in this experiment does not colonize the gastrointestinal tract of Fischer-344 rats.     

32P-postlabelling analysis of DNA adducts from Fischer-344 rats administered 2,4-diaminotoluene.

Using 32P-postlabelling and thin layer chromatography, DNA adduct formation by the potent animal carcinogen 2,4-diaminotoluene in Fischer-344 rats was investigated. DNA from four different organs, liver, mammary gland, kidney and lung, were examined for adducts following single administration of this compound. DNA binding was detected in all four organs, with each producing one major and two minor adduct spots on autoradiograms. The adducts induced were qualitatively identical among the different organs, but quantitative differences were observed. The two target organs of 2,4-diaminotoluene induced carcinogenesis, the liver and mammary gland produced higher adduct yields, with levels up to 30-times higher than those for the two non-target organs. Since the liver is the principal target for 2,4-diaminotoluene induced carcinogenesis, we further examined DNA adducts from this site for the effects of different doses and time points. DNA binding in liver was detected following doses as low as 4.1 mumol/kg. At the highest concentration examined (2046 mumol/kg), the level of the major adduct was 29.2 adducted nucleotides per 10(7) total nucleotides. The yields for the two minor adducts were approximately one-tenth that for the major adduct. Following a 410 mumol/kg dose, DNA adduct removal over time was examined. DNA adduct removal exhibited biphasic kinetics, with a rapid initial phase followed by a slower rate of elimination. Up to 60% of maximum adduct levels persisted after 2 weeks. DNA binding by 2,4-diaminotoluene was also compared to that by its weakly carcinogenic analog, 2,4-dinitrotoluene. The two compounds produced identical adduct patterns, suggesting that they share common metabolites and adducts. Adduct yields from 2,4-dinitrotoluene, however, were lower. The results of our studies suggest that the differences in carcinogenic potency between 2,4-diaminotoluene and 2,4-dinitrotoluene, as well as the organotropic effects of 2,4-diaminotoluene may be explained, in part, by quantitative differences in the extent of DNA adduct formation.     

Effects of oxidative stress on the pharmacokinetics and hepatic metabolism of atazanavir in rats

Abstract

We studied the effects of oxidative stress (OS) on the pharmacokinetics of atazanavir (ATV), particularly the distribution of ATV in the plasma and its metabolism in hepatic microsomes, using a rat model of ferric-nitrilotriacetate-induced OS (OS rats). The areas under the plasma concentration–time curves for intravenous bolus, oral, and intraportal administration of ATV in the OS rats were significantly greater than those in the control rats, whereas blood clearance of ATV after intravenous bolus injection in the OS rats (0.94 ± 0.04 L/h/kg) was approximately half of that in the control rats (2.08 ± 0.20 L/h/kg). Moreover, the intrinsic clearance (CLint), which is determined by in vitro metabolic studies using hepatic microsomal fractions of rats, was approximately 43% lower in the OS rats (0.489 ± 0.017 mL/min/mg protein) than in the control rats (0.851 ± 0.004 mL/min/mg protein). ATV concentrations in both the plasma-bound fraction and erythrocytes of the OS rats were significantly greater than those in the control rats. These results suggest that the hepatic metabolism of ATV may be reduced in patients under OS.