Conductance recording of ionic outflow from frog skin glands during nerve stimulation

Abstract

A method for continuous recording of the ionic efflux from frog skin glands has been developed which under given experimental conditions provides a convenient index on glandular secretion. A nerve skin preparation from the calf is mounted so that the outside of the skin forms the bottom of a small test compartment with distilled water while the corium side is bathing in Ringer's solution. After determination of the adequate nerve stimulus parameters for discernible gland secretion to occur, the skin nerve was stimulated at 10 Hz during varying periods and chemical control analyses performed of the changes in ionic content of the test compartment solution. The main ionic outflow consisted of Na+ and Cl- in equal amounts, the outflow of other ions during stimulation being negligible. The concomitant conductance changes were measured as variations of absorption in a high-frequency field applied to a conductance probe placed in the test chamber. Determinations of the NaCl outflow based on the conductance changes were in good agreement with the values obtained by chemical analysis. The continuous conductance recordings proved to give approximative information of the quantities and time relations of the glandular secretion, allowing a direct comparison with, e.g., skin potential changes.