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Activation of Human Sweat Glands using Intradermal Electrical Stimulation
Author(s) -
Mack Gary W.,
Gifford Jayson,
Heal Cory,
Goldthorpe Scott
Publication year - 2012
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.26.1_supplement.1084.2
Subject(s) - sweat , sudomotor , atropine , stimulation , sweat gland , capsule , iontophoresis , chemistry , pilocarpine , stimulus (psychology) , cholinergic , atropine sulfate , anesthesia , medicine , endocrinology , biology , psychology , botany , radiology , psychiatry , epilepsy , psychotherapist
A model for examining sweat gland function using intradermal electrical stimulation to activate sudomotor nerves (small sympathetic cholinergic C‐fibers) was examined in the dorsal aspect of the forearm in 10 healthy adults. We monitored the local sweat rate (SR) response of a small area of skin using small capsule (0.7 cm 2 ) containing a humidity sensor and thermocouple flushed with dry gas at 100 ml • min −1 . Two small stainless steel needles were place into the skin immediately outside of the capsule and stimulated at frequencies of 0.2, 1, 2, 4, 8, 16, 32, and 64 Hz at two current intensities (1.5 and 2.5 mA) for 30 s. The stimulus‐response characteristics of local SR were evaluated using a non‐linear four‐parameter logistic curve fitting equation. The increase in local SR reached a plateau at a stimulus frequency of 32 Hz. The peak local SR response was significantly greater at 2.5 than 1.5 mA (0.21 ± 0.08 and 0.40 ± 0.12 mg • min −1 • cm −2 , p<0.05). The stimulus frequency that produced 50% of the increase in local SR was similar for both current intensities and averaged 11.2 ± 1.3 Hz. Subjective ratings of pain (0 to 100 scale) during intradermal electrical stimulus increased in a linear manner starting at 6 ± 2 (“weak”) and rising to 34 ± 7 (“strong”) at 64 Hz and 2.5 mA. Delivery of a 1% atropine sulfate solution to the skin by iontophoresis (2 mA x 10 min) completely blocked the sweating response to intradermal electrical stimulation providing strong evidence that the local SR response was mediated by acetylcholine released in response to depolarization of the small sympathetic cholinergic C‐fibers. Intradermal electrical stimulation in combination with measurement of local SR can be used to quantify small C‐fiber function in human skin with minimal pain.