LIVER AND LUNG LATE ALTERATIONS FOLLOWING HEPATIC REPERFUSION ASSOCIATED TO ISCHEMIC PRECONDITIONING OR N -ACETYLCYSTEINE MARIA APARECIDA GALHARDO, M.D., 1 CLAUDEMIRO QUIREZE JU ´ NIOR, M.D., Ph.D., 2 PEDRO GABRIEL RIBOLI NAVARRO, M.D. (student), 1 RICARDO JOSE ´ MORELLO, M.Sc., 1 MANUEL DE JESUS SIMO ˜ ES, M.D., Ph.D., 3 and EDNA FRASSON DE SOUZA MONTERO, M.D., Ph.D. 1 * This study aimed the effect of n-acetylcysteine or ischemic preconditioning in hepatic and pulmonary damage after liver ischemia-reperfu- sion injury.Twenty-fourmale Wistar-EPM rats were assigned into four groups:(IR) Hepatic ischemia-reperfusion; (IPC) IPC achieved before hepatic ischemia; (NAC) Animals received NAC pretreatment; and Sham operated group. After 24 h ofhepatic reperfusion, blood, liver,and pulmonary samples were evaluated. Nonparametric tests were used (P 0.05). Aspartate aminotransferase levels were similar among experimental groups.Lower alanine aminotrasnferase levels were observed in sham group (P ¼ 0.04). IPC and NAC groups prevented from necrosis (P ¼ 0.027), apoptosis (P ¼ 0.003), and microvesicular steatosis (P ¼ 0.0007), but not from neutrophil infiltration in liver tissue.IPC and NAC treatmentreduced alveolarseptaledema (P ¼ 0.014),but did not preventfrom neutrophil infiltration or vascularcongestion.In conclusion,IPC and NAC attenuated hepatic and pulmonary damage after hepatic ischemia-reperfusion injury. V V C 2007 Wiley-Liss, Inc. Microsurgery 27:295–299, 2007. P rolonged vascular inflow occlusion is frequently neces- sary during complex liver surgery and transplantation. This ischemic insult followed by reperfusion is a com- mon cause of local and remote organ dysfunction, result- ing in increased patient morbidity and mortality. 1–3 Experimental models ofhepatic IR injury have been used to betterunderstand its mechanisms and to help achieving strategies of prevention and treatment, such as N-acetylcysteine and ischemic preconditioning. 4,5 N-acetylcysteine is a low molecular weight thiol,and has been used in the treatment of acetaminophen hepatitis and hemodynamic disturbances. 5,6 We and othershave described its protective properties against oxidative tissue injury,due to the increase in reduced glutathione levels and improvement in microcirculation. 2,5,7 Ischemic preconditioning was first described by Murry et al. 8 in an experimental modelof ischemic myocardium in dogs.Those authors observed that brief episodesof ischemia followed by reperfusion could render a tissue more resistant to a sustained ischemic insult. The precisemechanisms remain to bedetermined. 9 We have proved that ischemic preconditioning protects against hepatocellular and sinusoidal apoptosis and necro- sis in earlyandintermediatephasesof reperfusion injury. 10 Ischemicpreconditioning is responsible for a decrease in reactive species of oxygen during reperfusion. Therefore, it has potential protective properties in distant organs, such as the lungs. 11–13 Since pulmonarydamageafterreperfusion is also mediated by both cytokines and inflammatory cells, is- chemicpreconditioning and n-acetylcysteine might be used as single strategies for protection of both liverand lungs. 14 This study aimed the effects of ischemic precondition- ing and the pretreatment with N-acetylcysteine in hepatic and pulmonary damage, in the late phase of hepatic IR injury. METHODS Ethics The experimental protocol was approved by UNIFESP’s EthicsCommitteeon Animal Researchguidelines. It used forty male rats, Rattusnorvegicus, EPM-1 Wistar strain,weighing around 350 6 50 g, aging 4 months. Animalswere keptin individualcagesbefore and after experiments, receiving water and commercial chow ad libitum. Animals and Preparation Animals were randomized in four groups of ten each. Animal preparation consisted of ketamine and xylazine anesthesia (60 and 10 mg/kg, respectively) intramuscu- larly, followed by a midlinelaparotomy and hydration with warm saline solution (3 mL/kg). Animals were kept over a heating pad during all experimental procedures. 1 Division ofOperative Technique and Experimental Surgery,Departmentof Surgery, Federal University of Sa ˜o Paulo (UNIFESP/EPM), Sa ˜o Paulo, Brazil 2 Department of Surgery, Federal University of Goia ´s (UFG), Goia ˆnia, Brazil 3 Division ofHistology,Department of Morphology, Federal University of Sa ˜o Paulo (UNIFESP/EPM), Sa ˜o Paulo, Brazil Grant sponsor: NationalCouncil for Scientific and Technological Develop- ment (CNPq), Brasil; Grant number: 302677/2003-8. *Correspondence to:Edna Frasson de Souza Montero,Alameda Espada, 134 – Res. Onze – Alphaville,CEP 06540-395,Santana de Parnaı ´ba, Sa ˜o Paulo, Brazil. E-mail: edna.montero@gmail.com Received 11 March 2007; Accepted 14 March 2007 Published online 3 May 2007 in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/micr.20359 V V C 2007 Wiley-Liss, Inc.