[Effects of furosemide on endocochlear potentials, auditory action potentials and summating potentials and the changes of inner ear pathology].
Guinea pigs were injected with furosemide 50 mg/kg (group A) and 25mg/kg (group B). Two minutes after injection, EP of group A decreased to -13.9mv while that of group B decreased to +65 mv. Also, AP of group A disappeared, and recovered at 8.5 mins. while AP amplitude of group B decreased to 78%. The SP value of group A changed from -14.5mv to +23.4mv 1 min after injection and returned to negative polarity in 12 min. Edema of stria vascularis was observed under light microscope. Transmission electron microscope showed edema between marginal cells and intermedia cells, cytoplasm of the marginal cell protruded to the cochlear duct, and cell membrane of outer hair cell folded. The finding of this study illustrates that furosemide inhibits the transportation of the active ions of cochlear duct tissue resulting in decrease of EP and alters the function of hair cells causing the change of AP amplitude. -SP depends on the ion transportation, the polarity can be inversed while large dosage of furosemide was used.
Wang
L
L
Navy General Hospital, Beijing.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003051:Cochlea / Q000187:drug effects; D003055:Cochlear Microphonic Potentials / Q000187:drug effects*; D004487:Edema / Q000139:chemically induced; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005665:Furosemide / Q000494:pharmacology*; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000648:ultrastructure; D013316:Stria Vascularis / Q000473:pathology* / Q000648:ultrastructure; D000159:Vestibulocochlear Nerve / Q000187:drug effects* / Q000502:physiology
D005665:Furosemide