Nature of the endocochlear dc potential in kanamycin-poisoned guinea pigs

The endocochlear dc potential (EP) was measured in normal guinea pigs and in a group poisoned with kanamycin sulfate for 60 minutes after the administration of furosemide intravenously (IV) or by perfusion into the scala tympani. The EP decreased rapidly and developed a large negative potential after IV administration of furosemide, but the EP decreased more slowly and did not develop a negative potential in kanamycin-poisoned animals. With perfusion of the scala media, the EP declined slowly and did not develop a large negative potential in either group. With perfusion of the scala tympani, the EP declined slowly in the kanamycin-poisoned animals and did not develop a large negative potential, while in the normal animals the EP declined rapidly and developed a large negative potential.