Effects of Epidermal Hydration on Skin Potential Responses and Levels

ABSTRACT Hydration of the epidermis promotes swelling of the stratum corneum, mechanical blockages of the sweat gland pore in the epidermis, and subsequent inhibition of surface sweating. If sweating continues in combination with poral closure, the resultant increase in hydrostatic pressure in the sweat duct is likely to alter the permeability of the sweat gland membrane. The experiments reported here investigated the significance of these effects for negative and positive skin potential responses (SPRs), and for the prestimulus levels associated with these responses. Hydration was found to virtually eliminate positive SPRs and to greatly reduce the prestimulus levels. A similar, though somewhat less drastic, effect was found for negative SPRs and prestimulus level. The hydration produced by a standard electrolyte (0.5% KCl in an agar jelly medium) appears to show a curvilinear time course with a rapid initial phase followed by slowly increasing hydration throughout a 20‐min period. The results were attributed to poral closure and to increased conductance through the epidermal pathway and were discussed in connection with recently suggested models of the electrodermal effector system.