Action of mannitol in ciguatoxin-intoxicated rats

This study reports the effects of mannitol on nerve conduction when used as a therapeutic agent in mammals following the administration of ciguatoxin. Electrophysiological studies were performed in vivo on the rat ventral coccygeal nerve. The absolute and relative refractory periods, conduction velocity and the supernormal response were measured in rats treated with i.p. ciguatoxin, both prior to, and following, the infusion of i.v. mannitol. Ciguatoxin induced significant prolongation of the absolute refractory period as well as significant slowing of the compound nerve conduction velocity. The magnitude of the supernormal response was significantly increased and the duration of the supernormal period extended in ciguatoxin-treated animals. Recordings collected following the infusion of mannitol in these ciguatoxin-treated animals showed that mannitol did not reverse the effects of ciguatoxin on nerve conduction in any of the parameters measured.