Livers from fasted rats subjected to 60 min of
hypoxia followed by 25 min of reflow exhibited a significant release of
lactate dehydrogenase (LDH) and
protein into the perfusate together with high rates of oxygen consumption, depletion of hepatic
glutathione (GSH) and accumulation of
thiobarbituric acid reactants (TBAR) in the liver. These changes were observed in the presence and absence of added
xanthine (25 microM) and were significantly diminished when experiments were carried out in the presence of either 1 mM
allopurinol or 100 microM
Trolox.
Allopurinol inhibited by 79% the production of
uric acid by the liver, which was not altered by
Trolox.
Hypoxia-reflow studies performed in the presence of 25 microM
2,4-dinitrophenol (DNP) showed a drastic enhancement in LDH (244%) and
protein (104%) efflux from the liver, compared with the effects found in its absence, with a moderate increase (35%) in tissue TBAR levels. Liver perfusion in the presence of both
allopurinol and DNP exhibited a normalization of the tissue content of GSH and TBAR, while the net increase in LDH and
protein release elicited by DNP alone was inhibited by only 20 and 25%, respectively. Similar results were obtained in experiments in which
allopurinol was replaced by
Trolox. These studies indicate that production of
oxygen free-radicals are involved in hypoxic liver injury upon reflow, but its relative importance is significantly diminished when energy stores are severely diminished.