Effects of carbon monoxide on cochlear electrophysiology and blood flow

Laurence D. Fechter, Peter R. Thorne, Alfred Nuttall

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

The belief that the cochlea is particularly vulnerable to a reduction in oxygen availability comes predominantly from studies reporting the disruption of electrophysiological measures, such as the compound action potential, endocochlear potential, inner hair cell intracellular potentials or afferent nerve fiber responses by asphyxiation. Because hypoxia has frequently been suggested as an underlying mechanism by which many ototoxic agents produce injury, and because such agents are not likely to completely disrupt oxygen delivery, we investigated the effects of graded hypoxia (using doses of carbon monoxide) on cochlear blood flow, the compound action potential (CAP) and the cochlear microphonic (CM). High doses of carbon monoxide injected intra-peritoneally yielded reversible loss of the CAP sensitivity for high frequency tone bursts, the extent of which was dose dependent. The loss was observed first at the highest frequency tested (50 kHz) and as carboxyhemoglobin levels increased, contiguous lower frequencies were influenced. Recovery progressed from low to high frequencies as carboxyhemoglobin levels declined. Carbon monoxide administration also produced a dose dependent elevation in the cochlear blood flow measured by a laser Doppler flow monitor. The data suggest that carbon monoxide administration disrupts cochlear function only under extremely severe exposure conditions. An elevation in cochlear blood flow may well serve as a protective mechanism which maintains cochlear function in the face of declining blood oxygen carrying capacity and delivery. While the site of action of carbon monoxide in the cochlea is uncertain, the data clearly indicate that elements involved in the generation of the CAP for high frequency tones are particularly vulnerable. This suggests that such elements may have different metabolic requirements from other lower frequency regions of the cochlea and/or that oxygen delivery (blood circulation) differs in the basal portion of the cochlea.

Original languageEnglish (US)
Pages (from-to)37-45
Number of pages9
JournalHearing Research
Volume27
Issue number1
DOIs
StatePublished - 1987
Externally publishedYes

Fingerprint

Electrophysiology
Cochlea
Carbon Monoxide
Action Potentials
Oxygen
Carboxyhemoglobin
Inner Auditory Hair Cells
Blood Circulation
Asphyxia
Conservation of Natural Resources
Nerve Fibers
Lasers

Keywords

  • Carbon monoxide hypoxia
  • Cochlear blood flow
  • Cochlear microphonic
  • Compound action potential
  • Laser Doppler
  • Ototoxicity

ASJC Scopus subject areas

  • Sensory Systems

Cite this

Effects of carbon monoxide on cochlear electrophysiology and blood flow. / Fechter, Laurence D.; Thorne, Peter R.; Nuttall, Alfred.

In: Hearing Research, Vol. 27, No. 1, 1987, p. 37-45.

Research output: Contribution to journalArticle

Fechter, Laurence D. ; Thorne, Peter R. ; Nuttall, Alfred. / Effects of carbon monoxide on cochlear electrophysiology and blood flow. In: Hearing Research. 1987 ; Vol. 27, No. 1. pp. 37-45.
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