1. A study was made of changes induced by cholinergic agonists and antagonists in the K+, Na+, Ca2+ and Cl− content of saliva of 22 human subjects with denervated parotid salivary glands.
2. At all stages after denervation there was an increased content of Na+ and Cl− in the secretion of the denervated gland as compared with that of the control glands: (a) after administration of pilocarpine and carbacholine; (b) after administration of a combination of atropine and pilocarpine; (c) in ‘paradoxical’ salivation induced by atropine, scopolamine, metacine or chlorosyle; (d) in spontaneous secretion; (e) in reflex secretion when this was partially restored.
3. The concentrations of Na+ and Cl− in the secretion of the denervated gland were disproportionately higher than would have been expected from the raised salivation rate.
4. Secretions from the denervated glands by virtue of their increased content of Na+ and Cl− resembled so-called primary saliva.
5. The increased output of Na+ and Cl− and high concentrations of these ions in the secondary saliva after denervation indicates that there is loss of the normal neural control over reabsorption of electrolytes in the epithelium of the glandular ducts. Further, that absence of this control results in disturbances of membrane ionic transport, of membrane permeability and of the metabolism of the gland.