Snake infrared receptors respond to dimethylsulfoxide in the blood stream

1. We used extracellular recording of the infrared (IR)-sensitive trigeminal ganglion (TG) neurons (primary neurons) of a crotaline snake, Trimeresurus flavoviridis, which has very sensitive thermoreceptors, to examine changes in the IR response induced by dimethylsulfoxide (DMSO), in vivo. 2. The responses in the TG were recorded after each concentration of DMSO (1, 10, and 25%) was administered in the bloodstream. 3. At a constant temperature, DMSO dose-dependently potentiated the IR-triggered discharges of IR-sensitive TG neurons in this snake. 4. It is suggested that the increased IR response to DMSO is due to its chemical effect, or to an indirect effect via its vasoactive role in the thermoreceptors of IR-sensitive snakes.