Effect of rHu-EPO on the reoxygenation injury to cultured hepatocytes. Cultured rat hepatocytes were pre-incubated in the presence or absence of rHu-EPO (10 U/ml) in L-15 medium (37°C) for 20 hours at normoxia (74% N2/21% O2/5% CO2). Then the cells were incubated in modified Krebs-Henseleit (KH) buffer, again with or without rHu-EPO, under deep hypoxia (for 120 minutes) followed by normoxia (37°C). In some experiments glycine (66 μM) was added before starting the hypoxic treatment; other experiments were performed using heat-inactivated (30 minutes at 100°C; heat-inactiv.) rHu-EPO. Cell injury was determined by the release of cytosolic lactate dehydrogenase (LDH). Values shown represent means ± S.D. of 4 independent experiments. *p < 0.05 (66 μM glycine and 10 U EPO/ml, heat-inactiv.) vs. respective incubations at hypoxia with no addition. Closed squares: hypoxia/reoxygenation, no addition; closed circles: hypoxia/reoxygenation, 10 U rHu-EPO/ml; closed triangles: hypoxia/reoxygenation, 10 U heat-inactivated rHu-EPO/ml; closed diamonds: hypoxia/reoxygenation, 66 μM glycine.