Modulation of the chloride concentration of human sweat by prolactin.

The purpose of this study was to determine whether the availability of PRL modulates the chloride concentration of human sweat. Full thickness human skin grafted into the back of immunoincompetent, nude, congenitally athymic mice heals in about 6 to 10 weeks and survives the life of the mice. Mice have no sweat glands in the back so this system provides a useful model for study of the physiology and pathology of human sweat glands. The graft can be induced to sweat and the sweat collected for analytical studies. Presumably normal skin obtained from 7 individuals undergoing reconstructive surgery was grafted successfully into 11 mice. On 49 occasions sweat was induced by pilocarpine iontophoresis and collected for 45 min. The chloride concentration was 12.9 +/- 6.7 meq/liter, values typical of normal human sweat. Nine mice bearing grafts were injected with rabbit anti-human PRL (hPRL). The chloride concentration of sweat obtained a day later was significantly elevated. The concentration generally increased after a second and sometimes a third injection of anti-PRL. The average maximum sweat chloride obtained was 61.9 +/- 8.25 meq/liter. Serum of rabbits that had not been exposed to hPRL was prepared and diluted in the same way as the anti-hPRL. The chloride concentration of sweat of 3 mice that received the preparation for several days remained unchanged at the low normal level. We conclude that depletion of PRL increases the concentration of chloride in human sweat.