Abstract
Biochemical and pharmacological evidence supports a role for nitric oxide (NO) in the cochlea. In the present experiments, we tested sodium nitroprusside (SNP), an NO donor, applied by intracochlear perfusions on sound-evoked responses of the cochlea (CM, cochlear microphonic; SP, summating potential; EP, endocochlear potential; CAP, compound action potential) and in vitro on outer hair cell (OHC) voltage-induced length changes and current responses. In vivo application of SNP in increasing concentrations (10, 33, 100, 330 and 1000 μM) reduced all sound-evoked responses starting at about 300 μM. The responses continued to decline after a postdrug wash. At 1 mM SNP decreased EP slowly (≈ 80 min) whereas at 10 mM it reduced EP more rapidly (≈ 20 min). Ferricyanide (1 mM) and S-nitroso-N-acetylpenicillamine (SNAP; 1 mM) had no effect on sound-evoked cochlear potentials. Ferricyanide (1 mM and 10 mM) and ferrocyanide (10 mM) had no effect on EP. In vitro, SNP (10 mM) significantly reduced both OHC voltage-induced length changes and whole-cell outward currents. Results suggest that SNP, possibly acting by released NO, influences cochlear function through effects at the stria vascularis and at the OHCs.
Original language | English (US) |
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Pages (from-to) | 1-8 |
Number of pages | 8 |
Journal | Hearing Research |
Volume | 87 |
Issue number | 1-2 |
DOIs | |
State | Published - Jul 1995 |
Externally published | Yes |
Keywords
- Electromotility
- Ferricyanide
- Ferrocyanide
- Nitric oxide
- S-nitroso-N-acetylpenicillamine
- Voltage-clamp
ASJC Scopus subject areas
- Sensory Systems