Premium
Quantitative assessment of cutaneous C‐fiber function in human skin via direct sudomotor activation
Author(s) -
Kunz Justin D,
Gillespie Michael A,
Mack Gary W
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb767
Subject(s) - sudomotor , atropine , chemistry , cholinergic , stimulation , carbachol , human skin , acetylcholine , stimulus (psychology) , sweat , endocrinology , medicine , biology , psychology , psychotherapist , genetics
Small sympathetic cholinergic C‐fiber function was examined using intradermal electrical stimulation to activate sudomotor nerves in the forearm skin of healthy humans. We measured local sweat rate (SR) with a 0.7 cm 2 capsule containing a humidity sensor and a thermocouple and flushed with dry gas. Two small stainless steel needles were place into the skin (7 mm apart, 2 mm deep) and stimulated at a constant current intensity of 2.5 mA for 30 s and 120 s at frequencies of 0.2, 1, 2, 4, 8, 16, 32, and 64 Hz. The stimulus‐response characteristics were evaluated using a non‐linear four‐parameter logistic curve fitting equation. Peak local SR occurred between 32 and 64 Hz and was similar for 30 and 120 s stimulus duration averaging 0.46 ± 0.2 and 0.49 ± 0.2 mg • min −1 • cm −2 , respectively. The EC50 averaged 8.3 ± 0.3 Hz during the 30 sec stimulus but decreased to 3.6 ± 0.05 Hz (p<0.05) during the 120 s stimulus. The area under the SR‐time curve following atropine sulfate (2 μg/ml) was lower than control (p<0.05) and not different from zero. These data support the hypothesis that the SR response to intradermal electrical stimulation reflects, exclusively, the effect of direct depolarization of sympathetic cholinergic C‐fibers and release of acetylcholine. As such, this model can be used to provide a quantifiable assessment of small C‐fiber function in human skin.