CIRCADIAN VARIATIONS IN FLOW-RATE AND COMPOSITION OF HUMAN STIMULATED SUB-MANDIBULAR SALIVA

Samples of ascorbic acid-stimulated submandibular saliva were collected from 16 subjects once every hour of a 24-hour period. Circadian rhythms were demonstrated in flow rate and concentrations of sodium, potassium, calcium, chloride, phosphate, protein, nitrogen and carbohydrate; these rhythms were best described by a combination of a fundamental sine curve of 24-h period and its first harmonic. Modal times of maxima and minima varied less between subjects with acid-stimulated saliva than between subjects with unstimulated saliva. The circadian range of values was approximately 50 per cent of the mean values. To minimize the variation due to circadian rhythms, stimulated submandibular saliva should preferably be collected in the early afternoon when most components show maxima or minima. © 1979.