Response of the infrared receptors of a crotaline snake to ethanol.

The pit organs of crotaline snakes can sense infrared (IR). The pit membrane has a finer, flatter, more convoluted vasculature than other sensory organs. Using extracellular recording from IR-sensitive trigeminal ganglion (TG) neurons (primary neurons) and tectal (OT) neurons of the crotaline snake Trimeresurus flavoviridis, we examined the IR response to ethanol (EtOH) in vivo. The response to EtOH was recorded in the TG and OT 20-80 s after 10% EtOH in Ringer's solution (100 microl/ 500 g body weight) was injected via the heart. The responses to EtOH and those to lower or higher temperature stimulation were additive. At a constant temperature (25 degrees C), EtOH significantly potentiated the IR-triggered discharges of IR-sensory pathways in this snake. These results suggest that the IR response to EtOH is due to either its vasodilatory effect on the abundant vasculature of the pit membrane or its chemical effect on temperature-sensitive receptors. Copyright 2002 Elsevier Science Ireland Ltd.