Heterogeneity of Damage Between Segments of Rat Liver After Inflow-Outflow Obstruction E. Polat, S. Topaloglu, C. Sokmensuer, E. Topaloglu, F.M. Avsar, H. Ozel, O. Saygun, I. Yildiz, G. Ucar, and S. Hengirmen ABSTRACT Background. Total vascular exclusion (TVE) causes warm liver ischemia. The complete explanation of the events during inflow and outflow obstruction of the liver during selective TVE has not yet been studied. The aim of this study was to investigate the liver injury caused by inflow-outflow obstruction in the rat liver. Materials and methods. Forty Wistar-Albino rats were divided into four groups. Liver inflow occlusion (groups A and C) or inflow-outflow occlusion (groups B and D) was applied for 30 minutes. Samples were collected at the end of the ischemia period. We examined oxidative injury in the liver tissue and liver histopathology. Results. Oxidative stress and histopathologic alterations were more prominent with TVE application. Significant alterations were shown in hepatic superoxide dismutase, glutathione, and glutathione S-transferase levels. Central segments of the rat liver were affected significantly from inflow occlusion, whereas dome segments were significantly damaged from inflow-outflow occlusion. Conclusions. Inflow-outflow occlusion of the liver caused more tissue damage compared with inflow occlusion. The pattern of distribution of the damage due to TVE seemed different from other well-known ischemia-reperfusion injuries. I SCHEMIA-REPERFUSION injury of the liver is a chal- lenging clinical problem in liver transplantation and hepatic surgery. Mechanisms responsible for the cellular damage associ- ated with ischemic and hypoxic liver injury are still being investi- gated. Some investigators have focused on the topographic dissociation of liver injury during ischemic and hypoxic liver injury. 1–17 Controversies about the distribution of cellular dam- age during ischemia-reperfusion of the liver still continue. Total vascular exclusion (TVE) causes warm liver ischemia. 18 However, this type of injury seems different from that due to inflow occlusion. 19,20 Application of caval blockage during TVE results in additional alterations in hemodynamics. 21 Our experimental studies have focused on selective application of TVE to the rat liver. 20,22 The aim of this study was to investigate the segmental and zonal distribution of liver injury caused by inflow-outflow obstruction to the rat liver. We compared the injury secondary to inflow-outflow obstruction with that due to inflow obstruction. MATERIALS AND METHODS Forty male Wistar-Albino rats weighing between 180 and 200 g were used for the study. They were kept under routine laboratory conditions and received standard laboratory chow with free access to food and water. Experimental Design The animals were divided into four groups of 10 animals: (group A): 30-minute hepatic inflow occlusion and tissue sampling for biochemical analyses, (group B): 30-minute hepatic inflow occlu- sion and tissue sampling for microscopic analyses (group C): 30-minute hepatic inflow-outflow occlusion and tissue sampling for biochemical analyses and (group D) 30-minute hepatic inflow- outflow occlusion and tissue sampling for microscopic analyses. All animals were sacrificed at the end of the ischemia period. From Department of Pathology (C.S., I.Y.), School of Medi- cine, Hacettepe University, Ankara; Department of Surgery (E.P., S.T., F.M.A., H.O., S.H.), Ankara Numune Training and Research Hospital, Ankara; Department of Biochemistry (E.T., G.U.), School of Pharmacy, Hacettepe University, Ankara; and Depart- ment of Surgery (O.S.), School of Medicine, Kirikkale University, Kirikkale, Turkey. Address reprint requests to Serdar Topaloglu, MD, Uzun- Altuntas Apt. No. 12, Cinaralti Caddesi, Besirli Mah, Trabzon, Turkey. E-mail: serdartopaloglu@yahoo.com © 2006 by Elsevier Inc. All rights reserved. 0041-1345/06/$–see front matter 360 Park Avenue South, New York, NY 10010-1710 doi:10.1016/j.transproceed.2006.08.097 Transplantation Proceedings, 38, 3075–3081 (2006) 3075