COLD PRESERVATION-INDUCED CHANGES IN OXYGEN RADICAL GENERATION BETWEEN PARENCHYMAL AND NONPARENCHYMAL CELLS IN RAT-LIVER

Many of the reports implicating the contribution of oxygen radicals to preservation-reperfusion injury have been based largely on indirect e xperiments demonstrating the effects or the consumption of various ant ioxidants. Investigations based on the direct measurement of the amoun ts of oxygen radicals that are actually formed during reoxygenation af ter preservation have not given satisfactory results. In this study, w e attempted direct measurement of H2O2 from hepatocellular mitochondri a and superoxide (O-2(-)) from Kupffer cells, using the HRP method and cytochrome c perfusion method, respectively, for quantitative compari son of the cold preservation-induced changes in radical generation act ivity between these sources. H2O2 generation in mitochondria isolated after 24 h cold preservation decreased to 8% of non-preserved liver, b ut in the mitochondria isolated from the livers that were reperfused f or 30 min after 24 h preservation H2O2 generation recovered to 60%. Th e respiratory control ratio also decreased significantly after 24 h pr eservation, and similarly recovered after an additional 30 min reperfu sion. By contrast, O-2(-) from Kupffer cells increased in time-depende nt fashion until 12 h preservation and decreased after 24 h preservati on. Although 12 h preservation did not cause an increase in LDH releas e, the lipid peroxide in the perfusate significantly increased after 1 2 h preservation, which indicated the occurrence of lipid peroxidation in the sinusoidal area. These results suggested that mitochondrial H2 O2 was dependent upon the activity of respiratory function and so did not cause hepatocellular injury and that O-2(-) from Kupffer cells con tributed to oxidative injury to the sinusoidal lining cells. Our data support reports demonstrating the vulnerability of nonparenchymal cell s.