CAPSAICIN AND ITS ANALOGS INDUCE ION CHANNELS IN PLANAR LIPID BILAYERS

THE irritating, pungent compound, capsaicin (10-20 mu M), induces the formation of non-selective ion channels with a wide variety of conductances in protein-free lipid bilayers formed from a mixture of zwitterionic phospholipids. The channel-forming activity of capsaicin and four of its analogs followed the sequence: resiniferatoxin > capsaicin = pelargonic acid vanillylamide > methylcapsaicin >> veratrylamine. The ability to form channels correlated with the biological activity of these compounds observed in other studies that measured Ca-45 uptake into rat dorsal root ganglion cells. The correlation obtained suggests that an interaction with the lipid bilayer may be an important component of the biological activity of capsaicin.