A technique for studying the effects of drugs on human sweat gland activity.

Abstract

A technique is described for studying the effects of drugs with anticholinergic properties on human forearm sweat glands. The response of sweat glands to intradermal injections of increasing concentrations of acetylcholine (ACh) in saline was measured. The number of glands activated was recorded by painting the injection area with a plastic impression paint one minute after injection. The plastic impression was removed using “Sellotape”, mounted on a 35 mm slide, projected, and glands counted. Standardisation of conditions was important with respect to ambient temperature and physical activity of subject in order to reduce spontaneous sweat gland activity. The dose response relationship was similar for men and women. In a double blind, controlled, cross over investigation, 8 subjects (4M and 4 F) received lactose dummy and atropine sulphate 1 mg p. o. Sweat gland activity, salivation, heart rate, pupil size and visual near point were measured before and 1 and 2 h after treatment. Significant (P<0.05) reduction occurred in the number of glands responding to 140 and 550 µM ACh and also in the salivary secretion rate 2 h after atropine, compared with values after lactose dummy. No significant changes in pupil size, visual near point or heart rate occurred. It is suggested that inhibition of the response of forearm sweat glands to ACh is at least as sensitive as other measures of parasympathetic functions for assessing parasympatholytic agents.