The Arrhenius plot of inactivation (killing) rates of V-79 Chinese hamster cells exposed to hypothermia in air-equilibrated (aerobic) medium contains a break at about 8 degrees C, which corresponds to the minimum inactivation rate, implying that there are distinct hypothermic damage mechanisms above (range I, 8 to 25 degrees C) and below (range II, 0 to 8 degrees C) 8 degrees C. Prehypothermic hypoxia (PHH) for 75 min at room temperature sensitizes cells to subsequent aerobic hypothermia at both 5 and 10 degrees C (range II and I). However, PHH followed by severe hypoxia (0.03 microM oxygen in the medium) protected cells during 10 degrees C (range I) storage by increasing the shoulder, but not the slope, of the cell survival curve compared to the PHH plus 10 degrees C aerobic hypothermia case. On the other hand, PHH plus severe hypoxia during 5 degrees C storage (range II) protected cells by decreasing the slope, but not the shoulder, of the cell survival curve compared to the PHH plus 5 degrees C aerobic hypothermia case. Furthermore, PHH plus severe hypoxia during 5 degrees C storage was not significantly worse than aerobic storage without PHH at 5 degrees C. With or without severe hypoxia, 10 degrees C storage is preferable to 5 degrees C storage in this cell line. Extrapolated to organ storage, the results may imply that if warm ischemia (PHH) has occurred, subsequent hypoxic hypothermic perfusion storage may be preferable to aerobic hypothermic perfusion storage.