Cutaneous Microdialysis as a Novel Means of Continuously Stimulating Eccrine Sweat Glands In Vivo

Previous studies of the pharmacological regulation of sweat gland function in humans have administered agonists or antagonists systemically, by local intradermal injection or by iontophoresis. This has not allowed prolonged or steady-state activation of sweat glands to be examined. In this study, we used the technique of dermal microdialysis to administer pharmacological agents singly and in combination for up to 5hours. Muscarinic stimulation with pilocarpine nitrate (50μgml−1 to 1.66mgml−1) produced a sigmoid dose response curve, with maximal sweating (measured as transepidermal water loss) (mean 70gm−2hour−1) after 15minutes. This was sustained at steady-state levels (55gm−2hour−1) until perfusion stopped. Perfusion with atropine (0.003mgml−1) reduced sweating below baseline and blocked pilocarpine-induced sweating completely. Noradrenaline (0.005mgml−1) induced much lower sweat rates than pilocarpine (56.8±1.62gm−2hour−1 vs 8.2±1.2gm−2hour−1, respectively, P