Hypoxia per se can produce hepatic damage without death in rats

To evaluate the importance of hypoxia itself on halothane-induced hepatic injury in the rat, the question of whether hypoxia could injure the liver without causing death was investigated. Male Sprague-Dawley rats pretreated with phenobarbital (1 mg/ml of drinking water, 4 days) and deprived of food for 24 hours were exposed to 6%, 7%, 8%, or 10% inspired oxygen with 0%, 5%, or 7.5% carbon dioxide for 2 hours. Several rats died when given 6% oxygen with 0% or 7.5% carbon dioxide, but all other rats survived. Without carbon dioxide, oxygen at a concentration of 7% or 8% produced more injury than did room air, and 6% oxygen produced the most severe damage. These results demonstrate that in rats hypoxia per se may be an important factor in causing hepatic damage.