Biochemical studies of taste sensation: II. Labelling of cyclic AMP of bovine taste papillae in response to sweet and bitter stimuli.

Labeling of cyclic AMP of tase papillae and its responsiveness to tast stimuli has been measured using whole papillae from bovine tongue prelabeled with [ 8-(14) C] adenine. Labeling was measured in circumvallate and fungiform papillae, both of which contain taste buds, and in filiform papillae and small blocks of tongue epithelium, which are devoid of taste buds. No differences were observed in the levels of activity. The labeling of cyclic AMP of circumvallate papillae showed only small increases (12-22%) in the presence of the taste stimulus sucrose (sweet), and the stimulatory effects were not statistically significant. The increase due to sucrose was not potentiated by theophylline. No stimulation by sucrose was observed with epithelium controls. Lactose, which is a poor taste stimulus, did not stimulate labeling of cyclic AMP in taste papillae. Theophylline, caffeine, and quinine (bitter) stimulated labeling of cyclic AMP by up to 2-fold, as did L-Epinephrine. Evidence for a specific role of cyclic AMP as a second messenger in taste sensation was not obtained. It is suggested that cyclic AMP might provide a mechanistic basis for studying some of the effects of sweet and bitter compounds in mixtures.