Free epinephrine, norepinephrine and dopamine in saliva and plasma of healthy adults.

To investigate whether salivary catecholamine levels reflect short term changes of sympathoadrenal activity, we simultaneously measured plasma and saliva epinephrine, norepinephrine and dopamine concentrations at rest, during bicycle ergometry and during epinephrine infusion in 12 healthy adults, using a radioenzymatic method. Whereas all plasma catecholamines significantly increased during bicycle ergometry and epinephrine infusion, no changes were observed in the salivary catecholamine concentrations and the salivary catecholamine flow rate after stimulation by rhythmic chewing. Moreover, salivary catecholamine concentrations were related neither to heart rate nor to blood pressure. Obviously, free catecholamines are rapidly inactivated by enzymatic degradation, neuronal reuptake or extraneuronal uptake in tissues before they diffuse through the tight junctions into the saliva. Therefore, stimulated saliva catecholamine levels do not reflect short term changes in the activity of the sympathoadrenal nervous system.