Motion Sickness and Human Performance Laboratory, Israel Naval Hyperbaric Institute, Haifa.
The salivary flow rate and composition of 2 groups of 31 subjects, one group at each extreme of the seasickness susceptibility scale, were compared. No significant differences were found between the two groups in flow rates and electrolyte concentrations of whole resting and stimulated saliva. Amylase activity and rate of secretion in resting saliva were significantly higher in subjects susceptible to seasickness as compared with nonsusceptible subjects. Also, the total protein rate of secretion in resting saliva was significantly higher in the susceptible group. The present findings could be explained in terms of higher sympathetic tone in subjects susceptible to seasickness, and salivary amylase levels might be recommended as an additional parameter in the evaluation of seasickness susceptibility