The endocochlear potential (EP) of approximately +80 mV across the basilar membrane is maintained by the high K⁺ concentration of endolymph. Which ion channel is most critical for K⁺ recycling back to the stria vascularis after hair cell stimulation?

• A KCNQ4 channels in outer hair cells
• B Prestin (SLC26A5) in outer hair cells
• C Connexin 26 (GJB2) gap junctions in supporting cells ✓
• D TRPA1 channels in stereocilia

Explanation

After depolarisation of cochlear hair cells, K⁺ exits through basolateral channels and is recycled to the stria vascularis via a gap-junction network formed predominantly by Connexin 26 (encoded by GJB2) and Connexin 30 in the supporting cells (Deiters' cells, pillar cells) and fibrocytes. Mutations in GJB2 are the single most common cause of autosomal recessive non-syndromic sensorineural hearing loss (DFNB1) worldwide. Prestin is the motor protein responsible for outer hair cell electromotility.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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