TY - JOUR
T1 - Novel classes of responsive and unresponsive C nociceptors in human skin
AU - Schmidt, Roland
AU - Schmelz, Martin
AU - Forster, Clemens
AU - Ringkamp, Matthias
AU - Torebjörk, Erik
AU - Handwerker, Hermann
PY - 1995/1
Y1 - 1995/1
N2 - One hundred ninety-four cutaneous C-fibers were recorded from the human peroneal nerve; 118 units were found by mechanical stimuli and 76 units were detected by electrical stimulation through a surface electrode. Needle electrodes were then inserted for electrical intradermal stimulation in the innervation territory of the units. Afferent and efferent sympathetic C- fibers were identified by slowing of conduction velocity after activation either by physical or chemical skin stimuli, or by arousal maneuvers eliciting sympathetic reflexes. In addition to mechano-heat-responsive C units (CMH) also found in previous studies, we here report on novel classes of C nociceptors in human skin, namely, units responding only to mechanical stimuli (CM), units responding only to heating (CH), and units that were insensitive to mechanical and heating stimuli and also to sympathetic provocation tests (CM(i)H(i)). With the electrical search technique we found 45% CMH, 13% CM, 6% CH, 24% CM(i)H(i), and 12% sympathetic units. Excitation by topically applied mustard oil occurred in 58% of CMH units, and in one- third of CM and CM(i)H(i) units, respectively. Some CM, CH, and CM(i)H(i) units were sensitized to heating and/or to mechanical stimuli after topical application of mustard oil or capsaicin. These units then acquired responsiveness to a stimulus modality to which they previously were insensitive. Such recruitment of previously silent nociceptors implies spatial summation to the nociceptive barrage at central levels, and may contribute both to primary hyperalgesia to heat and pressure after chemical irritation, and to secondary hyperalgesia as a consequence of central sensitization.
AB - One hundred ninety-four cutaneous C-fibers were recorded from the human peroneal nerve; 118 units were found by mechanical stimuli and 76 units were detected by electrical stimulation through a surface electrode. Needle electrodes were then inserted for electrical intradermal stimulation in the innervation territory of the units. Afferent and efferent sympathetic C- fibers were identified by slowing of conduction velocity after activation either by physical or chemical skin stimuli, or by arousal maneuvers eliciting sympathetic reflexes. In addition to mechano-heat-responsive C units (CMH) also found in previous studies, we here report on novel classes of C nociceptors in human skin, namely, units responding only to mechanical stimuli (CM), units responding only to heating (CH), and units that were insensitive to mechanical and heating stimuli and also to sympathetic provocation tests (CM(i)H(i)). With the electrical search technique we found 45% CMH, 13% CM, 6% CH, 24% CM(i)H(i), and 12% sympathetic units. Excitation by topically applied mustard oil occurred in 58% of CMH units, and in one- third of CM and CM(i)H(i) units, respectively. Some CM, CH, and CM(i)H(i) units were sensitized to heating and/or to mechanical stimuli after topical application of mustard oil or capsaicin. These units then acquired responsiveness to a stimulus modality to which they previously were insensitive. Such recruitment of previously silent nociceptors implies spatial summation to the nociceptive barrage at central levels, and may contribute both to primary hyperalgesia to heat and pressure after chemical irritation, and to secondary hyperalgesia as a consequence of central sensitization.
KW - C- fibers
KW - human nociceptors
KW - hyperalgesia
KW - microneurography
KW - pain
KW - sensitization
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U2 - 10.1523/jneurosci.15-01-00333.1995
DO - 10.1523/jneurosci.15-01-00333.1995
M3 - Article
C2 - 7823139
AN - SCOPUS:0028861501
SN - 0270-6474
VL - 15
SP - 333
EP - 341
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 1 I
ER -