Effect of round window membrane application of nitric oxide on hearing and nitric oxide concentration in perilymph.
Nitric oxide (NO), a free radical, has been found to be important in the development of middle ear effusions. However, the effect of NO in the middle ear effusion on cochlear function and on perilymph concentrations of NO has not been reported. We placed S-nitroso-N-acetylpenicillamine (SNAP), a NO donor compound, on the round window membrane (RWM) of adult chinchillas. Auditory brainstem response (ABR) thresholds were measured before and after the placement of SNAP on the RWM and hourly for 8 h after SNAP placement. Samples of perilymph were collected 2 h after application of SNAP and were assayed for total nitrate and nitrite, the end products of NO. Experimental ears demonstrated significant ABR threshold elevations after 5 h and elevated nitrate/nitrite in the perilymph. These findings suggest that NO present in the middle ear passes through the RWM into the inner ear and can cause significant hearing loss.
Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, Loma Linda University School of Medicine, Jerry L. Pettis Memorial Veterans Medical Center, Loma Linda, CA 92354, USA.
Jonathan B
JB
Hanson
Paul T
PT
Russell
Andy T A
AT
Chung
Claire S
CS
Kaura
Samantha H
SH
Kaura
Earnest O
EO
John
Timothy T K
TT
Jung
D000818:Animals; D002682:Chinchilla; D003051:Cochlea / Q000187:drug effects / Q000503:physiopathology; D004195:Disease Models, Animal; D005260:Female; D006309:Hearing / Q000187:drug effects* / Q000502:physiology; D034381:Hearing Loss / Q000139:chemically induced* / Q000503:physiopathology; D006320:Hearing Tests; D008297:Male; D009566:Nitrates / Q000032:analysis*; D020030:Nitric Oxide Donors / Q000009:adverse effects* / Q000494:pharmacology*; D009573:Nitrites / Q000032:analysis*; D010498:Perilymph / Q000737:chemistry* / Q000187:drug effects*; D012405:Round Window, Ear / Q000187:drug effects* / Q000503:physiopathology; D026423:S-Nitroso-N-Acetylpenicillamine / Q000009:adverse effects* / Q000494:pharmacology*; D012720:Severity of Illness Index; D013997:Time Factors
D009566:Nitrates; D020030:Nitric Oxide Donors; D009573:Nitrites; D026423:S-Nitroso-N-Acetylpenicillamine