Influence of atropine on taste-stimulated parotid secretion

Elemental taste qualities as "sour" and "sweet" showed different stimulatory effects on the parotid secretion when given in concentrations with comparable gustatory intensity. Sweet (fructose 10%) exerted an adrenergic-like activity, sour (citric acid 1%) a more parasympathetic-like influence on parotid secretion. The vagal pathway of the gustatory stimuli was further investigated by the simultaneous infusion of atropine sulfate (17 micrograms/kg per 30 min). Atropine reduced the flow rate during sour and sweet stimulation in the range of 500% and 300%. In 60% of the test persons parotid flow rate could not be totally depressed in any of three 10-min sampling fractions by atropine when a sour stimulus was applied; in these subjects protein and amylase concentration increased significantly. Following fructose stimulation the flow rate was totally depressed in all subjects by atropine in the 20- and 30-min sampling fractions. In the first 10-min fraction protein and amylase concentration were not influenced by atropine. The cholinergic pathway seems to be responsible primarily for the flow rate and has further different modulating influence on the stimulatory effect of the individual taste qualities.