Reactive oxygen species in human inner ear perilymph.
CONCLUSIONS
The results reported here provide the first evidence of the production of superoxide, a biologically relevant reactive oxygen species (ROS), in human inner ear perilymph (hIP) in pathological conditions, by the activity of the xanthine dehydrogenase/xanthine oxidase (XA/XO) enzyme system.


OBJECTIVE
To investigate the presence of ROS in hIP.


METHODS
Since damage and apoptosis of inner ear hair cells may occur as a result of ROS-mediated injury, we investigated the presence and production of ROS in 105 hIP samples; 98 collected from patients affected by profound sensorineural hearing loss, during surgery for cochlear implantation, and 7 controls, collected from patients affected by otosclerosis, in case of spontaneous leakage after stapedotomy. ROS production was investigated by spectrophotometric analysis and polyacrylamide gel electrophoresis (SDS-PAGE).


RESULTS
In hIP samples tested by cytochrome c reduction kinetics, the average superoxide production was 27.34 mumoles per mg of total protein, against 0.36 in controls. Some of these hIP samples, analyzed by cytochrome c reduction kinetics in the presence of xanthine, were found to be positive for ROS-producing XA/XO enzyme. These results were supported by SDS-PAGE analysis.
Ciorba
Andrea
A
Department of Audiology, University Hospital of Ferrara, 44100 Ferrara, Italy. andrea.ciorba@unife.it
Gasparini
Pierluigi
P
Chicca
Milvia
M
Pinamonti
Silvano
S
Martini
Alessandro
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003054:Cochlear Implants; D045304:Cytochromes c; D007758:Ear, Inner / Q000378:metabolism* / Q000473:pathology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000378:metabolism; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010040:Otosclerosis / Q000378:metabolism; D010498:Perilymph / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013053:Spectrophotometry; D013201:Stapes Surgery; D014527:Uric Acid / Q000378:metabolism; D055815:Young Adult
D017382:Reactive Oxygen Species; D014527:Uric Acid; D045304:Cytochromes c