The Relation of Palmar Sweat Gland Activity to Level of Skin Potentialand Conductance

The role of sweat gland activity in the mediation of skin potential and skin conductance levels was investigated. l‐Hyoscyamine was introduced into the fingertips by iontophoresis to eliminate sweat gland activity, and d‐hyoscyamine, an inert analog of the l‐isomer, was used as a control for ion size. Neostigmine was used to potentiate sweating. l‐Hyoscyamine significantly decreased skin conductance level and the number of active sweat glands and reduced the negativity of skin potential level, but neostigmine, which promoted sweating and skin conductance, did not increase the negativity of skin potential. The lowering of skin potential on the denervated hand of a hemi‐sympathectomized patient was found to be similar in magnitude to the decrease in skin potential due to pharmacological elimination of sweat gland activity. The results are discussed in relation to hypotheses concerning the mechanism of skin potential.