To examine the sweating function in atopic dermatitis (AD), we investigated the sweating response of the lesional and nonlesional skin of adult patients with AD by a quantitative sudomotor axon reflex test (QSART) in which the axon reflex is stimulated by acetylcholine 10 % iontophoresis. All experiments were carried out in a climatic chamber (24±0.5°C, relative humidity 40±3% and less than 1 m/sec air velocity). Upon arrival into the climatic chamber, the subject wore light indoor clothing and sat on a chair for 60 min before the QSART. Sweat volume on the volar aspect of the forearm was measured in 18 adult patients with AD and in 40 nonatopic controls were also studied as disease comparators. In the atopic patients, all measurements were performed on both lesional and nonlesional skin. We also evaluated the sweating function in four AD patients after topical corticosteroid therapy. Latency time of reflex-mediated indirect, direct (DIR) sweat volume, and axon reflex-mediated indirect (AXR) sweat volume were the variables studied. The results showed that latency time in AD patients was significantly prolonged and AXR significantly reduced compared with those in nonatopic control subjects. The latency time and AXR sweat volume of the AD lesional skin were significantly more prolonged and reduced, respectively, than those of the nonlesional skin. In contrast, the DIR sweat volume of the lesional or nonlesional AD skin induced by direct stimulation with acetylcholine was not significantly reduced when compared with that in nonatopic controls. Latency time of reflex-mediated indirect and sweat volumes of the lesional and nonlesional AD skin improved after topical corticosteroid therapy. These results suggest that the impaired sweat response in AD is attributable to an abnormal sudomotor axon reflex, which is reversed by topical corticosteroid administration.
Source: Korean J Physiol Pharmacol.2001 Dec;5(Suppl II):S92-S93
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