Culture of cochlear explants and HEI-OC1 cells

The anesthetic rats were quickly decapitated, and the whole inner ears were harvested. After opening bulla and removing the cochlear shell, the basilar membrane was quickly dissected out and incubated in DMEM/F12 medium (Gibco, Carlsbad, CA) intermingled with 10% fetal bovine serum (FBS, Gibco) and ampicillin (50 μg/ml). The explants were cultured at 37 °C in 5% CO₂. Following the assessment of destroying effect of SM on the cochlea, the length of each explant was measured and three regions were chosen representatively as the apical, middle, and basal turns, at 5–14%, 40–49%, and 75–84% of the total length of basilar membrane away from the apex, respectively.

HEI-OC1 cells were cultured in DMEM basic medium (Gibco) with 10% FBS under permissive conditions (33 °C, 10% CO₂). No antibiotics were added into the medium except the SM. All operations concerning this cell line were conducted at the logarithmic phase.