Negative Potential in Scala Media During Early Stage of Anoxia

Abstract

Negative potential in scala media during early anoxia was recorded in both normal and kanamycin-treated guinea pigs. In kanamycin-treated animals, in which the cochlear microphonic was remarkably depressed, decline of the dc potential was slower and its negative value smaller than in non-treated animals. After prolonged asphyxia, amplitude of postmortem cochlear microphonic was increased by an anodal current. The polarity of the negative potential could be changed by application of positive pressure to scala vestibuli, whereby the postmortem cochlear microphonic was enhanced. However, neither application of pressure nor current produced any enhancement of cochlear microphonic after the negative potential in scala media reached zero. These data indicate that the negative potential in the scala media of the asphyxiated cochlea is ascribed to depolarization of the normally polarized hair-bearing ends of the hair cells and that stria vascularis is sensitive, while the hair-bearing ends of the hair cells are insensitive to oxygen deprivation.