Paradoxical effect of hypothermia on survival of lesioned and uninjured mammalian spinal neurons.

Survival of cultured spinal neurons 2 h after dendrotomy increased significantly when the temperature was reduced to 17 degrees C or 7 degrees C. Survival of lesioned neurons maintained at 17 degrees C for 2 h and then at 37 degrees C for 22 h was still significantly higher than survival of neurons maintained at 37 degrees C for 24 h. Below 17 degrees C both lesioned and uninjured neurons swelled. Upon rewarming to 37 degrees C, many swollen neurons died. Ketamine prevented hypothermic swelling and neuronal death.