Effects of furosemide on intracochlear oxygen tension in the guinea pig.

The effects of intravenous furosemide on the perilymphatic oxygen tension of the scala tympani (OT) in the guinea pig and the relationship between changes in OT and changes in auditory cortical-evoked responses were studied, as well as changes in cochlear morphology. Furosemide in dosages of 25 mg/kg and 50 mg/kg caused a sharp decline in OT in addition to elevation of the threshold of auditory cortical-evoked responses. Ischemia of the cochlear stria vascularis was also found but without any damage of hair cells at the light microscopic level. Changes in OT were associated with transient threshold elevations and ischemia of the stria vascularis. Improvements in hearing were directly proportional to the recovery of OT.