The control of potassium (86Rb+) efflux in the isolated human sweat gland.

Sweat glands, isolated from strips of human skin and pre-loaded with 86Rb+, a marker of potassium transport, were superfused with physiological saline and rate constants for 86Rb+ efflux calculated. The rate of efflux during superfusion with Ca2+-free saline was lower than that measured in the presence of calcium (2.56 mM). Acetylcholine increased the rate of 86Rb+ efflux and this response could be resolved into two components: an initial transient phase which was Ca2+-independent and a slowly declining Ca2+-dependent phase. Adrenaline only caused a Ca2+-dependent increase in efflux. It is suggested that the potassium permeability of the secretory cells increases during activity.