Immunolocalization of voltage-gated calcium channel alpha1 subunits in the chinchilla cochlea.

The immunohistochemical localization of alpha1A, alpha1B, alpha1C, alpha1D, and alpha1E voltage-gated calcium channel subunits was investigated in the chinchilla organ of Corti and spiral ganglia with the use of specific antipeptide antibodies. The inner and outer hair cells were immunoreactive for alpha1A and alpha1D subunit antibodies. Alpha1C immunoreactivity localized to the nerve terminals innervating inner hair cells and the basal pole of the outer hair cell. There was only non-specific staining to alpha1B and alpha1E. Supporting cells were non-immunoreactive. Spiral ganglia neurons were alpha1B, alpha1C, and alpha1D immunoreactive. A few spiral ganglia neurons were alpha1E immunoreactive. The importance of alpha1D, the pore-forming subunit of the L-type channel, in outer and inner hair cell function has been clearly demonstrated in electrophysiological, molecular biological, and knockout models. The presence of alpha1A, the pore-forming subunit of the P/Q type channels, has not previously been demonstrated in inner and outer hair cells, and its function in the cochlear hair cell is unknown.