Excitation of rat cutaneous nociceptors by noxious cold.
Electrophysiological recordings were made from mechanosensitive nociceptors innervating hairy skin of the rat hindpaw, and responses evoked by a wide range of noxious cold stimuli (20 to -12 degrees C) were determined. All A delta and C nociceptors sampled were excited by noxious cold. Response thresholds of A delta nociceptors were significantly higher (colder stimulus temperatures) than thresholds of C fibers, and many exhibited response thresholds below 0 degree C. Responses of both classes of nociceptors increased as stimulus temperature decreased. These data demonstrate that A delta and C nociceptors are excited by a wide range of cold stimuli and suggest that the proportion of cutaneous nociceptors excited by noxious cold has been underestimated in previous studies.
Simone
D A
DA
Department of Psychiatry, University of Minnesota, Minneapolis 55455, USA.
Kajander
K C
KC
D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways; D000818:Animals; D003080:Cold Temperature; D004594:Electrophysiology; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000294:innervation*