Mechano-insensitive nociceptors encode pain evoked by tonic pressure to human skin
R Schmidt, M Schmelz, HE Torebjörk, HO Handwerker - Neuroscience, 2000 - Elsevier
R Schmidt, M Schmelz, HE Torebjörk, HO Handwerker
Neuroscience, 2000•ElsevierSingle unmyelinated axons in the superficial branch of the peroneal nerve of human
subjects were recorded (microneurography) and the response patterns during tonic
pressure stimulation (14N at 30mm2; 120s) were assessed using the previously described
“marking technique”. It was found that tonic pressure stimuli induced augmenting pain
responses which were matched by the discharges of initially mechano-insensitive (“silent”)
C-units, whereas mechano-and heat-responsive “polymodal” C-nociceptors showed a …
subjects were recorded (microneurography) and the response patterns during tonic
pressure stimulation (14N at 30mm2; 120s) were assessed using the previously described
“marking technique”. It was found that tonic pressure stimuli induced augmenting pain
responses which were matched by the discharges of initially mechano-insensitive (“silent”)
C-units, whereas mechano-and heat-responsive “polymodal” C-nociceptors showed a …
Single unmyelinated axons in the superficial branch of the peroneal nerve of human subjects were recorded (microneurography) and the response patterns during tonic pressure stimulation (14N at 30mm2; 120s) were assessed using the previously described “marking technique”. It was found that tonic pressure stimuli induced augmenting pain responses which were matched by the discharges of initially mechano-insensitive (“silent”) C-units, whereas mechano- and heat-responsive “polymodal” C-nociceptors showed a response pattern incompatible with the stimulus-induced perceptions, namely strong initial excitation, followed by adaptation. Eighteen mechano- and heat-responsive “polymodal” C-fibers and 11 mechano-insensitive units were studied. The former had von Frey thresholds <160mN, the latter were not excited by a von Frey filament of 750mN (six of them responded to radiant heat stimulation). However, in the course of pressure stimulation, nine of the 11 mechano-insensitive units were activated after more than 20s. A second, identical pressure stimulus induced a stronger response in mechano-insensitive and a weaker response in mechano-responsive units. The stronger response, indicating sensitization, matched the more intense pain perception during the second pressure stimulus. It is concluded that mechano-insensitive C-nociceptors encode pressure-induced pain in human hairy skin and that they play an important role in static mechanical hyperalgesia.
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