Search

Background: Heat shock proteins (HSPs) are induced in the liver after warm ischemia/reperfusion and are thought to be markers of hepatocellular injury and oxidative stress., Methods: The influence of variable periods of cold storage followed by reperfusion on the expression of HSP70 was studied in the isolated perfused pig liver. Organs were harvested and stored in histidine-tryptophan-ketoglutarate solution at 4 degrees C and then perfused (210 min) in a closed water bath (38 degrees C), which subjects the liver to fluctuating outer pressure. The role of energy depletion, reactive oxygen intermediates, Kupffer cells, and circulating leukocytes in HSP70 expression was determined., Results: HSP70 expression was not detectable in liver tissue before explantation or before reperfusion by Northern blot analysis using a pig HSP70 gene probe. HSP70 expression was observed after reperfusion depending on cold storage time. Kinetics of HSP70 expression monitored by reverse transcriptase polymerase chain reaction showed a rapid increase of mRNA within 1 hr, which was closely associated with delayed recovery of hepatocellular energy charge, as assessed by the ketone body ratio. The inactivation of Kupffer cells, the presence or absence of leukocytes, and the suppression of oxidative stress with the antioxidant idebenone, given during reperfusion, had no influence. However, feeding the animals with idebenone over 7 days before explantation led to a faster recovery of ketone body ratio, paralleled by a substantial suppression of HSP70 expression., Conclusions: Our data show that HSP70 expression during reperfusion is mainly dependent on the preceding cold storage time and the consecutive delayed recovery of the hepatocellular energy charge.

The ability of the benzoquinone coenzyme Q-10 or its derivative QSA-10 (idebenone) to protect against lipid peroxidation and protein damage mediated by the pro-oxidative system NADPH/ADP/Fe3+ was tested in a rat liver microsomal model incubated in University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate (HTK) solutions. Lipid peroxidation, as followed by direct determination of lipid hydroperoxides and by monitoring of malondialdehyde equivalents, was 1.8-fold enhanced in HTK and 3-fold attenuated in UW compared with HEPES buffer. Function and integrity of microsomal enzymes were investigated using glutathione S-transferase and cytochrome P-450 IIIA activity as assessed by lidocaine N-deethylation to monoethylglycinexylidide as well as by Western blot analysis of the cytochrome P-450 IIIA protein. Glutathione S-transferase activity was reduced by about 70% in HEPES compared with 50% in HTK and 36% in UW. Cytochrome P-450 IIIA was inactivated by about 75% in HEPES and HTK, compared with 55% in UW. The enzyme inactivation was paralleled by a loss of immunoreactive cytochrome P-450 IIIA protein. Supplementation of HTK with 0.1 mumol/L QSA-10 offered complete protection against lipid peroxidation, compared with 100 mumol/L with Q-10. QSA-10 (20 mumol/L) prevented protein damage in both preservation solutions, whereas Q-10 (20 mumol/L) offered only partial protection in UW and had no effect in HTK. The use of QSA-10 during liver transplantation may therefore have the potential of increasing the efficacy of organ preservation, maintaining donor organ quality, and preventing reperfusion injury. It is suitable for human use and has energy-conserving properties in addition to its antioxidant nature.