Slow depolarizing stimuli differentially activate mechanosensitive and silent C nociceptors in human and pig skin
| Autor: | Ellen Jørum, Richard W. Carr, Otilia Obreja, Roman Rukwied, Martin Schmelz, Barbara Namer, Inge Petter Kleggetveit, Christian Thomas, Fiona Werland |
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| Rok vydání: | 2019 |
| Předmět: |
Pain Threshold
Swine Stimulation Human skin 03 medical and health sciences 0302 clinical medicine 030202 anesthesiology medicine Animals Humans Skin Nerve Fibers Unmyelinated Chemistry Chronic pain Nociceptors Depolarization Microneurography medicine.disease Axons Electric Stimulation Anesthesiology and Pain Medicine nervous system Neurology Nociceptor Mechanosensitive channels Axon reflex Neurology (clinical) Neuroscience 030217 neurology & neurosurgery |
| Zdroj: | Pain. 161(9) |
| ISSN: | 1872-6623 |
| Popis: | High-threshold mechanosensitive and mechanoinsensitive ("silent") nociceptors have similar electrical thresholds for transcutaneous sine wave stimulation at 4 Hz that selectively activates cutaneous C nociceptors in human skin. Their fundamentally different functions particularly in chronic pain warrant differential stimulation protocols. We used transcutaneously delivered slow depolarizing stimuli (half-sine, 500 ms duration, 0.01-1 mA) in humans to assess intensity-response relations for the induction of pain psychophysically and recorded activation of mechanosensitive and silent nociceptors in healthy volunteers by microneurography. Differential C-fiber activation was confirmed in single-fiber recordings in pig allowing for stimulation amplitudes up to 10 mA. Perception and pain thresholds to half-sine wave pulses were 0.06 ± 0.03 mA and 0.18 ± 0.1 mA, respectively, and caused pain in an amplitude-dependent manner (n = 24). When matched for pain intensity, only sine wave stimulation induced an instant widespread axon reflex erythema (n = 10). In human microneurography, half-sine stimulation activated mechanosensitive nociceptors (n = 13), but only one of 11 silent nociceptors. In pig skin, the amplitude-dependent activation of mechanosensitive nociceptors was confirmed (0.2-1 mA, n = 28), and activation thresholds for most silent nociceptors (n = 13) were found above 10 mA. Non-nociceptive low-threshold mechanosensitive C fibers (n = 14) displayed lower activation thresholds for half-sine wave stimuli with an amplitude-dependent discharge increase between 0.01 and 0.1 mA. We conclude that transcutaneous electrical stimulation with 500-ms half-sine wave pulses between 0.2 and 1 mA causes amplitude-dependent pain by preferential activation of mechanosensitive C nociceptors. |
| Databáze: | OpenAIRE |
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