The effects of nimodipine and thyrotropin-releasing hormone (TRH) were compared in a clip-compression model of experimental spinal cord injuries (SCI) in rats. Thirty rats received a 50-g clip-compression injury on the cord at T9. Ten rats were given 0.02 mg/kg nimodipine and dextran 40 (3 ml) i.v. 1 h after injury. Ten rats were given 2 mg/kg TRH and dextran 40 (3 ml) i.v. 1 h after injury followed by 1 mg/kg per hour for 4 h. The remaining ten rats were given only saline. TRH treatment significantly improved somatosensory-evoked potentials (SEPs) and mean arterial blood pressures (MABPs), whereas nimodipine treatment had no effect on these variables (Fisher's exact test (P < 0.01).