TY - JOUR
T1 - The electrochemical and fluorescence detection of nitric oxide in the cochlea and its increase following loud sound
AU - Shi, Xiaorui
AU - Ren, Tianying
AU - Nuttall, Alfred L.
N1 - Funding Information:
This work was supported by NIH research Grants NIDCD R01 DC00105 and DC 00105 25S1.
PY - 2002
Y1 - 2002
N2 - A nitric oxide (NO)-selective sensor (tip diameter 30 μm) was inserted into the perilymph of the basal turn of the guinea pig cochlea. The basal level and stimulation-induced changes of NO were measured. The mean (±S.E.M.) basal level of NO was 273±42.9 nM. Following perilymphatic perfusion of the artificial perilymph containing NO synthase (NOS) substrate L-arginine (100 μM) combined with cofactor (6R)-5,6,7,8-tetrahydrobiopterin dihydrochloride (100 μM), a rapid and significant increase of NO to a mean concentration of 392±32.3 nM (P<0.01, n=10) was recorded. In contrast, a significant decrease of mean NO concentration to 180±32.7 nM (P<0.01, n=10) was observed following the perfusion of the NOS-inhibiting agent NG-nitro-L-arginine methyl ester (100 μM). No change in the NO concentration was found following the perfusion of either artificial perilymph or NG-monomethyl-D-arginine (100 μM) solution employed as controls. Broadband noise exposure (3 h/day at 120 dBA SPL) for three consecutive days produced an increase in NO concentration to 618±60.7 nM (P<0.05, n=10) in the perilymph. In addition, by using specific dyes for NO, 4,5-diaminofluoresceine diacetate and for the reactive oxygen species (ROS), dihydrorhodamine 1,2,3, the distribution of NO in the whole mounts of the organ of Corti and the production of ROS in vivo in the organ of Corti were investigated in both control (n=5) and noise-exposed (n=5) animals. The more intense NO and ROS fluorescence was observed in both the inner and outer hair cells in the noise-exposed groups. It is proposed that both the basal level and the increase in NO concentration following the addition of substrate (L-arginine) are produced by the constitutive NOS while the elevated NO and ROS following noise exposure indicate that NO may be involved in noise-induced hearing loss.
AB - A nitric oxide (NO)-selective sensor (tip diameter 30 μm) was inserted into the perilymph of the basal turn of the guinea pig cochlea. The basal level and stimulation-induced changes of NO were measured. The mean (±S.E.M.) basal level of NO was 273±42.9 nM. Following perilymphatic perfusion of the artificial perilymph containing NO synthase (NOS) substrate L-arginine (100 μM) combined with cofactor (6R)-5,6,7,8-tetrahydrobiopterin dihydrochloride (100 μM), a rapid and significant increase of NO to a mean concentration of 392±32.3 nM (P<0.01, n=10) was recorded. In contrast, a significant decrease of mean NO concentration to 180±32.7 nM (P<0.01, n=10) was observed following the perfusion of the NOS-inhibiting agent NG-nitro-L-arginine methyl ester (100 μM). No change in the NO concentration was found following the perfusion of either artificial perilymph or NG-monomethyl-D-arginine (100 μM) solution employed as controls. Broadband noise exposure (3 h/day at 120 dBA SPL) for three consecutive days produced an increase in NO concentration to 618±60.7 nM (P<0.05, n=10) in the perilymph. In addition, by using specific dyes for NO, 4,5-diaminofluoresceine diacetate and for the reactive oxygen species (ROS), dihydrorhodamine 1,2,3, the distribution of NO in the whole mounts of the organ of Corti and the production of ROS in vivo in the organ of Corti were investigated in both control (n=5) and noise-exposed (n=5) animals. The more intense NO and ROS fluorescence was observed in both the inner and outer hair cells in the noise-exposed groups. It is proposed that both the basal level and the increase in NO concentration following the addition of substrate (L-arginine) are produced by the constitutive NOS while the elevated NO and ROS following noise exposure indicate that NO may be involved in noise-induced hearing loss.
KW - Guinea pig
KW - L-Arginine and (6R)-5,6,7,8-tetrahydrobiopterin dihydrochloride
KW - N-Nitro-L-arginine methyl ester
KW - Nitric oxide electrode
KW - Noise exposure
KW - Polarography
KW - Reactive oxygen species
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U2 - 10.1016/S0378-5955(01)00409-9
DO - 10.1016/S0378-5955(01)00409-9
M3 - Article
C2 - 11950524
AN - SCOPUS:0036206878
SN - 0378-5955
VL - 164
SP - 49
EP - 58
JO - Hearing Research
JF - Hearing Research
IS - 1-2
ER -