A model for studying saliva secretion in the conscious dog.

Parotid saliva secretion was studied in conscious dogs in which a chronic fistula of the parotid duct was provoked by a simple surgical procedure. To validate the technique employed, the responsiveness of the gland to various stimuli was examined. The volume of secretion was measured as well as the concentrations of Na+, K+ and calcium. Secretion was elicited by administering bethanechol i.v. or by feeding a meat meal. These stimuli, applied repetitively in the same animal, evoked reproducible secretory responses. In addition, the dose-response curve to bethanechol could also be constructed. The parotid secretion is controlled by muscarinic receptor activation, as illustrated by atropine blockade and its insensitivity to adrenergic drugs. The preparation is a versatile model which allows to investigate secretion evoked by both direct and reflex activation. The advantages of the preparation, which avoids invasive techniques, are accurate measurements and reproducible responses over long periods in a conscious animal.