EFFECTS OF TEMPERATURE ON SILKMOTH OLFACTORY RESPONSES TO PHEROMONE CAN BE SIMULATED BY MODULATION OF RESTING CELL-MEMBRANE RESISTANCES

Electrophysiological parameters were measured at different temperature s in resting and pheromone-stimulated olfactory sensilla trichodea of male Antheraea polyphemus (Saturniidae). A method for selective coolin g of either the olfactory hair or the antennal branch was developed. T he resting preparation resistance increased with lower temperatures, t he transepithelial potential decreased. These effects were also observ ed when the antennal branch was cooled, but were absent during cooling the hair, suggesting a major influence of auxiliary cells on the tran sepithelial potential and resistance. Together with the preparation re sistance, the responses to pheromone stimuli increased with lower temp eratures. Computer simulation of the current flow in the sensillum sho wed that the temperature dependence of responses to pheromone can be e xplained by modulation of resting resistances of cell membranes alone, without effects of temperature on stimulus transduction. The weak tem perature dependence of transepithelial potential might be due to tempe rature dependence of the electrogenic pump producing the transepitheli al potential. Selective cooling of the olfactory hair had no effect on the shape of nerve impulses, cooling of the antennal branch caused ch anges similar to that obtained by cooling the entire sensillum. This s upports the idea that the nerve impulses are generated in the soma of the receptor cell.