Functional activity of the sweat glands in the hairy skin of sheep.

Abstract

Using the iodine-starch method for visualizing sweat from active sweat gland ducts, the functional activity of the sweat glands in the hairy skin of sheep was studied. Intradermal injections of adrenaline elicited a local sweat response at low concentrations such as 10-8 and 10-7. Intravenous infusion of adrenaline at a rate of 0.5 μg/kg•min was definitely effective in producing general sweating. Intradermal noradrenaline was also effective, but it was a little less potent than adrenaline. In contrast, intradermal injections of parasympathomimetic agents such as pilocarpine and acetylcholine were without any sudorific effect, even when the concentration was raised up to 10-3. Eserine was also ineffective. Thermoregulatory sweating could be produced by heat application. By partial sympathectomy alone or combined with bilateral adrenal medullectomy, it was established that thermoregulatory sweating was produced primarily by excitation of the sympathetic adrenergic sweat nerves when heating was mild, and additionally by catecholamines from the adrenal medulla when their secretion was increased in association with heating. By testing with intradermal nicotine and lobeline, it was found that the sweat nerves in the sheep have no receptors responsible for the sweating axon reflex.