Cyclic adenosine 3', 5'-monophosphate levels in human parotid saliva at different secretion rates

Seventy-four samples of unstimulated and stimulated parotid saliva were collected from 12 healthy male volunteers. The secretion rates and cAMP concentrations were determined. The secretory rate ranged from 0.01 to 1.03 ml/min/gland. The concentration of cyclic AMP varied from 1.6 to 31.9 pmol/ml. The concentration of cAMP was 10.0 +/- 6.5 pmol/ml in unstimulated saliva and 3.8 +/- 1.6 pmol/ml in stimulated saliva. A curvi-linear relationship existed between secretory rate and cyclic AMP concentrations, and the best-fitting regression equation was y = 2.06 + 0.5/x, where y = concentration of cyclic AMP and x = secretory rate.