Phototoxicity-light is painfully blue.

摘要: The capsaicin and mustard oil receptors TRPV1 and TRPA1, respectively, are highly expressed in polymodal nociceptors, ubiquitous thin nerve fibers that can evoke pain and induce" neurogenic inflammation" by neuropeptide secretion. Reversible oxidation of intracellular cysteine residues of these channel proteins causes activation and sensitization to adequate stimuli. The ion channel activity can be assessed in cultured sensory neurons, transfected cell lines, and in artificial lipid bilayers, using patch-clamp recording, calcium microfluorimetry, and indirectly by single-fiber recording and enzyme immunoassay measurement of stimulated neuropeptide (CGRP) release from isolated organ preparations. Strikingly, we found that ordinary blue light (405 nm) activates human TRPA1 and evokes pain in white human skin. This results from the ubiquitous presence of the heme precursor protoporphyrin IX (Pp IX) that acts …