Red blood cells attenuate sinusoidal endothelial cell injury by scavengingxanthine oxidase-dependent hydrogen peroxide in hyperoxic perfused rat liver

Aims/Background Rat liver perfused with an oxygenated buffered solution alo ne results in degenerative changes even when the perfusion flow is accelera ted to give a sufficient oxygen supply. On the other hand, perfusion media supplemented with red blood cells (RBCs) preserve the viability of the live r. The present study was conducted to clarify how RBCs protect the isolated perfused liver. Methods: The liver was perfused with and without RBCs in a perfusate equilibrated with supra-physiological oxygen tension at regulate d inflow pressures, and controlled hepatic oxygen consumption. We examined alanine aminotransferase and purine nucleoside phosphorylase activity in th e perfusate as specific markers of liver cells injury. Hydrogen peroxide (H 2O2) production and morphological changes were determined using cerium elec tron microscopy. Apoptosis was detected by measuring CPP 32 protease activi ty and using TdT-me-dieted dUTP-digoxigenin nick end-labeling. Results: Whe n the liver was perfused with RBC-free buffer, H2O2 production and conseque nt injury progressing to apoptosis were initiated in the sinusoidal endothe lial cells (SECs). After SECs were injured, H2O2 appeared in the hepatocyte s. H2O2 production and associated degenerative changes were attenuated both morphologically and enzymatically by the addition of RBCs, a specific xant hine oxidase (XOD) inhibitor and the H2O2 radical scavenger, catalase. Conc lusions: In the liver perfused with RBC-free buffer, H2O2 production and co nsequent injury were initiated in SECs. RBCs attenuate liver injury by scav enging XOD-dependent H2O2.