Salivary changes associated with experimental motion sickness condition in man.

The effect of experimental motion sickness condition (rotation) on salivary flow and composition was studied in 34 healthy male volunteers. In most subjects, the flow rate of whole saliva was significantly decreased, while the potassium concentration was markedly increased during rotation. These results contrast with the classic reports of subjectively increased salivation in the first stages of motion sickness and may tentatively be explained in terms of sympathetic activation. The salivary protein concentration and secretion rate observed before and during rotation were consistently higher in those subjects categorized as moderately or severely sick during rotation. The salivary protein levels may perhaps be considered as an additional objective variable in the prediction of susceptibility to motion sickness.