Charybdotoxin improves motor recovery of the rat after spinal cord injury.

Charybdotoxin, a highly specific inhibitor of calcium-activated potassium efflux, was found to protect rat spinal cord against dynamic impact injury. In a control (nontreated) group, a weight drop of 10 gram X 5 cm on the T-11 segment of the rat spinal cord paralyzed hindlimbs, and recovery was slow. After 4 weeks, Tarlov scores (a behavioral index) were 1 to 2; the hind legs could not support body weight. In contrast, with animals pretreated 30 minutes prior to the injury by 0.12 mg charybdotoxin/kg (IP), Tarlov scores increased to 3.5-4.5 by three weeks after injury; animals could walk with some deficit. A possible mechanism for the protective effect of this drug is discussed.