Interaction of a calcium channel blocker with noise in cochlear function in guinea pig

Abstract

Conclusions: Both nifedipine and noise exposure had damaging effects on cochlear function. These damaging effects were subtractive rather than additive, suggesting that calcium channel blockers may have a protective role in noise-induced hearing loss. Objective: We assessed the interaction of nifedipine, a calcium channel blocker, with noise in cochlear function by evaluating changes in the compound action potential (CAP) threshold after the administration of nifedipine with or without noise exposure. Methods: Eighty guinea pigs were randomly assigned to eight groups based on those with cochlear perfusion with nifedipine only (0, 0.15, 0.5, and 3 µM, groups 1–4) and noise exposure (groups 5–8). CAP thresholds were recorded using a round window electrode before and 120 min after cochlear perfusion. Results: Cochlear perfusion of different concentrations of nifedipine caused 2.5, 5.5, 28, and 21.5 dB SPL threshold shift, respectively, at 0, 0.15, 0.5, and 3 µM concentrations (groups 1–4). In comparison, the CAP thresholds after nifedipine perfusion with noise exposure were 43.5, 46.5, 20, and 21.5 dB SPL, respectively, in groups 5–8.

Keywords::

• Noise exposure
• cochlea
• action potential

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.