Effect of glycerol and mannitol on perilymphatic PO2 in guinea pig cochlea

The effects of glycerol and mannitol on partial oxygen pressure (PO2) in perilymph were studied with a polarographic technique in the guinea pig cochlea. Following a transient reduction immediately after the intravenous injection of each drug, the oxygen tension increased to reach a peak 5 to 10 minutes later, and then decreased gradually. The magnitude and duration of the PO2 increases were larger after the administration of glycerol than after that of mannitol. These results corresponded well with the clinical experience that glycerol was more effective than mannitol in improving hearing in Meniere's disease. The increase of PO2 in the cochlea, therefore, is considered to be one of the possible contributory factors for the improvement of hearing in patients with Meniere's disease after glycerol administration.