N1 latency prolongation in the guinea pig cochlea treated with nitrogen mustard-N-oxide studied by narrow band analysis.

The effect of nitrogen mustard-N-oxide (NMO) upon the click and tone burst-evoked N1 latency was examined in 14 albino guinea pigs. In all animals except one, the pseudothresholds of action potentials were elevated, especially in the high tone area. In addition to the amplitude reduction, the N1 latency was prolonged in 12 animals. The narrow band analysis of N1 revealed that the latency was equally prolonged in all frequency areas, although the amount of the amplitude reduction was much larger in the high frequency area. It was concluded that the prolongation of the N1 latency in NMO-treated animals was due to dysfunction of outer hair cells along the entire cochlear partition.