Cholinergic and adrenergic sweating in atopic dermatitis

Sweating responses to methacholine and adrenaline were compared with an evaporimeter in normal-looking back and forearm skin from patients with atopic dermatitis (AD) and from non-atopic controls (NA). With both stimulants, the sweat rates were higher in forearm than in back skin in both groups, and between the two sites the rates showed positive correlations which were statistically significant in both groups. With methacholine the responses were slightly depressed in both areas in AD. With a low suprathreshold adrenaline concentration (5 x 10(-6) mol/l) the responses were equal in both groups but a tenfold higher adrenaline concentration elicited an increase of 55% in sweating rates in the back skin of NA and a 15% depression in the back skin of AD subjects (p less than 0.05). On arm skin there was a similar trend, but less marked. Between the cholinergic and adrenergic sweating responses a positive correlation was found on arm skin in AD, suggesting that the unknown mechanism of sweat depression in AD might be the same for both drugs.