S1570 RAC1, Caveolin-1 and VEGF Mediated Liver Sinusoidal Endothelial Cell Angiogenesis

Abstract

A S L D A b st ra ct s from NHBD. Rat livers were explanted immediately after 30 min of aorta clamping, stored in UW solution at 0-1oC for 4 h, and then implanted. 1400W, a specific iNOS inhibitor, was added to the storage solution and the lactated Ringer's post-storage rinse solution at a concentration of 5 μM. Hepatic iNOS expression was detected by Western blotting. iNOS was barely detectable in livers from untreated rats and in cold-stored, unimplanted livers from NHBD. After transplantation, iNOS increased slightly in grafts from heart beating donors (HBD). By contrast, iNOS increased markedly in grafts from NHBD. Serum nitrite and nitrate levels were ~3-fold higher in rats received grafts from NHBD than from HBD, indicating formation of nitric oxide. Similarly, hepatic 3-nitrotyrosine adducts, an indicator of peroxynitrite formation, was substantially higher in grafts from NHBD than those from HBD after transplantation. Production of reactive nitrogen species (RNS) was largely blocked by 1400W. Alanine aminotransferase (ALT) release, serum bilirubin, and apoptosis were 2.7-, 10.0-, and 3.1-fold higher after transplantation of grafts from NHBD than grafts from HBD, indicating more severe liver injury in grafts from NHBD. Cleaved caspase-3 detected by Western blotting was significantly higher in grafts from NHBD than grafts from HBD after transplantation, further conforming the occurrence of apoptosis. 1400W almost totally blocked these alterations. Survival decreased from 100% after transplantation of grafts from HBD to 33% after transplantation of grafts from NHBD. 1400W increased survival of grafts from NHBD to 80%. Previous studies showed that activation of c-Jun-N-terminal kinase (JNK) caused mitochondrial dysfunction and cell death after liver transplantation. Phosphorylated JNK and phosphorylated c-Jun increased substantially in grafts from NHBD after transplantation, and these effects were blocked by 1400W. In summary, hepatic iNOS increased substantially after non-heart beating liver transplantation, which leads to overproduction of RNS, JNK activation, and more severe graft injury. Inhibitors of iNOS are suggested as an effective therapy to improve the outcome of non-heart beating liver transplantation (NIDDK).