Objective    To investigate the effects of hypoxia and sodium cyanide (NaCN) on oxidative stress in rabbit arterial blood.     Methods    An artificial hypobaric hypoxia chamber was used to simulate 4 000-meter high altitude. Twenty rabbits were randomly divided into 4 groups: hypoxia group with high- or low-dose

non-hypoxia with high- or low-dose. The animals in the non-hypoxia groups were operated under normal circumstances while those in hypoxia groups were subjected to chamber in low pressure for 72 h before receiving the hypoxia experiments. Femoral arterial cannulation was performed on all animals under anesthetization with pentobarbital sodium (30 mg/kg

iv) and NaCN(ip) at the doses of 1.5 mg/kg and 2 mg/kg. Blood samples were collected at 10 min before intoxication

and 5

10

15

20

30

60

120 and 180 min after intoxication and blood seperation was conducted. The activity of superoxide dismutase (SOD)

contents of reduced glutathione (GSH) and malondialdehyde (MDA) were determined.     Results    The MDA content was significantly increased (P0.01)

and the SOD activity and GSH level were obviously decreased by NaCN injections in the non-hypoxia animals (P0.05

  P0.01).  Similar changes were also detected under the hypoxia condition (P0.01) 72 h later yet

and the changes of the aboving indices were more distinct in hypoxia groups than in non-hypoxia groups 30 min after intoxication.      Conclusion    Either hypoxia or NaCN can produce significant changes on the oxidative stress system and theg may heve a synergetic effect.