Effect of capsaicin on potassium conductance and electromotility of the guinea pig outer hair cell.
Capsaicin, the classic activator of TRPV-1 channels in primary sensory neurons, evokes nociception. Interestingly, auditory reception is also modulated by this chemical, possibly by direct actions on outer hair cells (OHCs). Surprisingly, we find two novel actions of capsaicin unrelated to TRPV-1 channels, which likely contribute to its auditory effects in vivo. First, capsaicin is a potent blocker of OHC K conductances (I(K) and I(K,n)). Second, capsaicin substantially alters OHC nonlinear capacitance, the signature of electromotility - a basis of cochlear amplification. These new findings of capsaicin have ramifications for our understanding of the pharmacological properties of OHC I(K), I(K,n) and electromotility and for interpretation of capsaicin pharmacological actions.
Oregon Hearing Research Centre, NRC04, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Sciences University, 3181 S.W. Sam Jackson Park Rd., Portland, OR 97239, United States.
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D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects*; D025802:Electric Capacitance; D005455:Fluorescent Antibody Technique; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects* / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000187:drug effects*; D008564:Membrane Potentials; D051379:Mice; D018345:Mice, Knockout; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D050916:TRPV Cation Channels / Q000172:deficiency / Q000235:genetics
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D011188:Potassium; D002211:Capsaicin