Temperature dependence of the response of the pyridine-sensitive units in the crayfish walking leg

Summary The responses of single pyridine-sensitive neurons ofAustropotamobius torrentium (formerlyOrconectes limosus) to pyridine were recorded extracellularly at different temperatures of the bath solution (between 6–30 °C). There was marked temperature dependence of the receptor response with a Q₁₀ of about 4, which was independent of the stimulus concentrations. With prolonged exposure to temperatures >22 °C the initially uniform discharge gives way to rhythmical bursts of action potentials. A characteristic hysteresis loop was obtained with an up-and-down temperature step program. In conformity with previous studies, an effect of ambient temperature on the time course and amplitude of action potentials was found. The results show that the spontaneous activity of the pyridine-sensitive neurons was not influenced by temperature changes. Evidently the temperature dependence of the response of pyridine receptors is based on a mechanism quite different from that underlying the properties of thermoreceptors of other arthropods.Abbreviations H van Harreveld solution - 4-AP 4-aminopyridine - TTX tetrodotoxin - TEA tetraetylammonium