The influence on spinal cord evoked potentials of chymopapain applied to the rat lumbar spine canal.

Electrically evoked compound action potentials were used to quantify the neurophysiologic abnormalities caused by application of chymopapain into the lumbar spinal canal in rats. A branch of the sciatic nerve was stimulated with voltage impulses of constant amplitude (40 V) and duration (0.1 msec) at the right external malleolus. The responses were recorded at the dorsal root entry zone L1. The authors used different doses of chymopapain (low dose = 100 IU, middle dose = 250 IU, and high dose = 500 IU). The control rats were subjected to exactly the same stimulus and recording procedures, but the test solution was a corresponding volume of isotonic saline. The prolongation of the latency of the electrically evoked potential due to chymopapain is very clear at the doses of 250 IU and 500 IU, being about 10 to 15% relative to the mean latency before application of the drug. This study indicates that locally applied chymopapain has a dose-dependent effect on nerve conduction properties.