Capsaicin and its analogs induce ion channels in planar lipid bilayers.

The irritating, pungent compound, capsaicin (10-20 microM), induces the formation of non-selective ion channels with a wide variety of conductances in protein-free lipid bilayers form 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 45Ca 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.