Acquisition deficits induced by sodium nitrite in rats and mice.

Graded doses of sodium nitrite were administered shortly before or immediately after a single training trial in an inhibitory avoidance task. A retention test was given at 24 h (rats) or 72 h (mice) after training. The results indicate that sodium nitrite impairs acquisition of an inhibitory avoidance response in rats and mice. Retention was impaired with doses lower than those required for producing hypoxic effects, as measured by the EEG, methemoglobin levels in the blood, blood pressure, and heart rate. Since hypoxia was not involved, it is likely that the effects were mediated by some direct action of sodium nitrite on the CNS.