Cold transduction by inhibition of a background potassium conductance in rat primary sensory neurones

Transduction in cutaneous cold receptors is poorly understood at present. We have studied this question using dorsal root ganglion (DRG) neurones in primary culture as a model of the otherwise inaccessible receptor terminal. Whole-cell recordings during cooling from 32 to 20 degreesC revealed a large depolarization (> 8mV) in 22 of 88 DRG neurones (25%), sometimes accompanied by action potentials. In cold-sensitive neurones cooling inhibited a time-independent background K+ current (I-cold) which was resistant to tetraethylammonium and 4-amifiopyridine. Ouabain elicited a substantially smaller depolarization than cooling, and no action potentials. We conclude that excitation by cooling in this model is primarily due to inhibition of I-cold and that the previously suggested role of the Na+/K+ adenosine triphosphatase is secondary. We suggest that I-cold may underlie cold transduction in cutaneous thermoreceptors. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.