cAMP and cGMP in the human parotid saliva

Human parotid saliva was revealed to contain considerable amounts of cAMP and cGMP. On sour lemon drop stimulation, the salivary cyclic nucleotides concentration decreased and the cyclic nucleotides secretory rate increased in close relationship with the salivary flow rate in control subjects. On feeding, both cAMP concentration and secretory rate increased significantly in control subjects. Parotid saliva from a patient of Sjögren's syndrom was revealed to have a significantly higher of cGMP concentration than those from control subjects. Saliva derived from the malignant tumor of the parotid gland was revealed to have a higher cGMP concentration and a lower cAMP concentration than the healthy site. From these findings, the possibilities of the clinical usefulness of studying salivary cyclic nucleotides were discussed.