Nitroprusside suppresses cochlear potentials and outer hair cell responses

Chu Chen, Anastas Nenov, Ruth Skellett, Maureen Fallon, Latasha Bright, Charles H. Norris, Richard P. Bobbin

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

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 languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalHearing Research
Volume87
Issue number1-2
DOIs
StatePublished - Jul 1995
Externally publishedYes

Keywords

  • Electromotility
  • Ferricyanide
  • Ferrocyanide
  • Nitric oxide
  • S-nitroso-N-acetylpenicillamine
  • Voltage-clamp

ASJC Scopus subject areas

  • Sensory Systems

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