Category: membrane
Transient receptor potential (TRP) channels are polymodal cation channels on primary sensory afferents (nociceptors + thermoreceptors). TRPV1 — capsaicin + heat (>43°C) + low pH; activation produces burning pain; desensitization on chronic exposure underlies topical capsaicin pain therapy. TRPM8 — menthol + cool (<25°C); activation produces cooling sensation. TRPA1 — mustard oil, cinnamaldehyde, environmental irritants; coupled with TRPV1 in noxious sensing. Therapeutic exploitation: high-concentration topical capsaicin (8% patch — Qutenza) for postherpetic neuralgia → defunctionalizes TRPV1+ nociceptive fibers. Menthol provides counter-irritant analgesia. Camphor + eucalyptol + thymol are TRPM8/TRPV1 polymodal activators present in over-the-counter musculoskeletal/respiratory rubs.