Effect of rHu-EPO on the hypoxic injury to cultured hepatocytes. Cultured rat hepatocytes were pre-incubated in the presence or absence of rHu-EPO (100 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 (37°C) for 5 hours, again with or without rHu-EPO, under deep hypoxia (gassing with 95% N2/5% CO2; closed symbols) or normoxic conditions (open symbol). In some experiments glycine (10 mM) was added before starting the hypoxic treatment; other experiments were performed using heat-inactivated (30 minutes at 100°C) 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 vs. respective incubations at hypoxia with no addition; glycine (10 mM) provided significant protection (p < 0.05) vs. respective incubations at hypoxia (not indicated). Closed squares: hypoxia, no addition; closed circles: hypoxia, 100 U rHu-EPO/ml; closed triangles: hypoxia, 100 U heat-inactivated rHu-EPO/ml; closed diamonds: hypoxia, 10 mM glycine; open squares: normoxia, no addition.