Methods of treating an injured vertebrate spinal cord are described. In one aspect of the invention, a method of treating an injured vertebrate spinal cord includes contacting the spinal cord with a biomembrane fusion agent such as a polyalkylene glycol, especially polyethylene glycol. In alternative embodiments of the invention, methods of treating an injured vertebrate spinal cord include contacting the cord with a biomembrane fusion agent and a potassium channel blocker. Other aspects of the invention include compositions for treating a vertebrate nervous system. A preferred composition includes a biomembrane fusion agent, such as a polyalkylene glycol, and a potassium channel blocker, such as an amino-substituted pyridine.