$76 POSTERS Table 2. Regional mean MTR (%) from the basal ganglia and frontal white matter of patients with cirrhosis Mean values Controls Patients p value a I• PROTEIN OXIDATION IN ASTROCYTE OF PORTO-CAVAL SHUNTED RATS: ROLE OF OXIDATIVE STRESS IN HEPATIC ENCEPHALOPATHY Age (sd) 53.3 (8) 51.2 (7.8) 0.6 Frontal white matter (sd) 57.7 (1.8) 55.3 (2.1) 0.02* Head of caudate (sd) 48.5 (2.1) 46.8 (2.1) 0.13 Putamen (sd) 48.3 (0.9) 47.4 (2) 0.28 Globus pallidus (sd) 52.7 (1.1) 49.8 (4.4) 0.11 Thalamus (sd) 53.1 (1.9) 52.9 (1.7) 0.81 ap value correspondsto t-test result. I-~QT PROLONGATION IS ASSOCIATED WITH RESISTANCE AGAINST EPINEPHRINE-INDUCED ARRHYTHMIA IN CIRRHOTIC RATS: THE ROLE OF NITRIC OXIDE AND ENDOGENOUS OPIOID PEPTIDES A.R. Hairasouliha, S. Tavakoli, R Jabehdar-Maralani, E Ebrahimi A.R. Dehpour. Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Background: QT prolongation is one of the main components of cirrhotic cardiomyopathy. It has been shown that QT prolongation, either congenital or acquired, predisposes patients to fatal ventricular arrhythmias. How- ever, susceptibility of cirrhotic patients or animals to epinephrine-induced arrhythmia, a main trigger of arrhythmia in conditions associated with QT prolongation, has not yet been evaluated. Aims: The aim of this study was to examine the susceptibility of chronic bile-duct ligated (CBDL) rats, as a known model of biliary cirrhosis, to epinephrine-induced arrhythmia. We also evaluated the role of nitric ox- ide (NO) overproduction and accumulation of endogenous opioid peptides in determination of QT interval and susceptibility to arrhythmia in this model. Methods: Three groups of rats, each of which was subdivided into two subgroups (sham-operated and CBDL), were examined. The first group of animals was treated with normal saline. The second and third groups received N(c0)-nitro-L-arginine methyl ester (L-NAME, nonselec- tive NO synthase inhibitor, 3 mg/kg/day) and naltrexone (20 mg/kg/day), respectively. Drug administrations were performed subcutaneously for six consecutive days during the fourth week following bile-duct ligation or sham operation. Four weeks after BDL or sham operation, animals were anesthetized with sodium pentobarbital (50 mg/kg, i.p) and ventilated with room air. The right carotid artery and left jugular vein were cannulated for arterial blood pressure measurement and drug injection. QT interval was determined using lead II of electrocardiogram and corrected for heart rate (QTc) according to Ba~zett's equation. After baseline measurements, ar- rhythmias were induced by intravenous injection of 10 gg/kg epinephrine. Results: Despite prolongation of QTc interval (P <0.001), epinephrine induced less arrhythmia in CBDL rats (P <0.05) compare to sham- operated animals. L-NAME administration corrected prolongation of QTc in CBDL rats (P < 0.01), and increased the susceptibility of CBDL rats to epinephrine-induced arrhythmia (P < 0.05) to the level of sham-operated rats. Naltrexone injection also resulted in correction of QTc prolongation in CBDL rats (P <0.001), but had no significant effect on epinephrine- induced arrhythmia (P > 0.05). Conclusions: This study shows that despite QTc prolongation, CBDL ani- mals are resistant against epinephrine-induced arrhythmia. It also suggests that NO, but not endogenous opioid peptides, contributes to development of this resistance. M. Jover1'2. D. Diaz-G6mez 2, E. Fontiveros 1, L. Collantes de Terfin 1, J. Parrado 1, I. Camacho 3, J. Bautista 1, M. Romero-Gomez2. 1Bioqu[mica, Bromatolog[a, Toxicolog{a y Medicina Legal, Universidad de Sevilla, Spain," 2Unidad de Hepatolog[a, UGCED, Spain," 3 Servicio de Bioqu[mica, Hospital Universitario de Valme, Sevilla, Spain The production of free radicals (FR), mainly, reactive oxygen species (ROS) and nitric oxide (NO) is induced in the astrocytes due to hyperammonemia (Murhy et al. J Neurosci Res 2001; 6:282 8). Re- cently, oxidative stress has been related to the physiopathology of hepatic encephalopaty (HE) (Norenberg et al. Metab Brain Dis 2004; 19). The production of carbonyl groups in proteins is a marker of protein oxidation (Butterfield et al. Mech Ageing Develop 2001:12:945462). Aims: Evaluation of protein damage caused by ROS and FR produced due to the hyperammonemia. We quantified carbonyl groups in proteins from mitochondria isolated from cerebellum, basal ganglia and cortex of porto-caval shunted rats (PCS). Materials and Methods: Wistar male rats weighting 250 300 g were used for this study. 8 PCS rats and 8 sham rats as control group were included. Non-synaptic mitochondrias were isolated by centrifugation using a ficoll gradient (12,000 g for 30 min. 6% to 3% Ficoll) according to Kosenko et al. Protein amount was quantified by Bradford assay and carbonyl groups by reaction with NDPH according to de Levine et al. Oxidated proteins were detected and quantified using an image analysis software and optical density was correlated to the amount of carbonyl groups in the samples. Results: Protein oxidation levels due to ROS were measured as total carbonyls, in PCS and sham rats were: 22,2• UOD (units of optical density) in PCS rats versus 17.9• UOD in control rats (statistically non-significant difference) in cerebellum; 17.8• UOD in PCS rats versus 7.6• UOD in control group (p < 0.01) in cortex, and 24.3• UOD in PCS group versus 10.4• in control rats (p <0.001) in basal ganglia. Electrophoretical analysis shows that the main proteins sensitive to oxidative damage have a molecular weights between 20 and 80 kDa, specially one protein of 72 kDa (non identified). Conclusions: Mitochondrial proteins from astrocytes of basal ganglia and cortex are more sensitive to oxidation damage than mitochondrial proteins from astrocytes of cerebellum. These preliminary results support the idea of the role of oxidative stress in the pathogenesis of HE. Acknowledgement to Ministry of health (G03/155), Red Nacional de Investigacidn en Encefalopatla Hepfitica. I-~ LOSARTAN IN COMBINATION THERAPY OF EXPERIMENTAL RAT LIVER FIBROSIS REVERSAL O. Lukivskayal~ E. Patsenkel 2, Yu. Popov 3, D. Schuppan 3, V. Buko 1. 1Department of Experimental Hepatology, Institute of Biochemistry, Grodno, Belarus," 2Department of Medicine I, University of Erlangen- Nuernberg, Erlangen, Germany," 3Beth Israel Deaconess Medical Cente~ Harvard Medical School, Boston, USA We studied the effects of losartan (LOS) combined with other novel antifibrotic agents, sylimarin (SYL), interferon a-2 (IFN), mycophenolate mofetil (MMF) and pioglytazone (PGZ), in experimental model of rat liver fibrosis reversal induced by thioacetamide (TAA). Advanced liver fibrosis was induced by TAA treatment (200 mg/kg, i.p.) during 3 months, 2 times per week. Resolution of fibrosis was monitored after 2 months of TAA withdrawal. During the last two months of the experiment, the TAA-treated groups were daily administered i.g. with LOS (5 mg/kg), SYL (50 mg/kg), PGZ (3 mg/kg), MMF (5 mg/kg) and 3 times perweek with IFN (150,000 IU/rat). The combinations of LOS with other agents were applied in similar dosage. The severity of liver fibrosis was