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Objective: We have recently reported that unstimulated whole saliva flow rates (UWSFR) correlate positively with salivary gland sizes and body profiles of weight and body mass indices. In the present study, the correlations of chewing-stimulated whole saliva flow rates (CWSFR) with salivary gland sizes and the body profiles were investigated, and the results were compared with those of UWSFR., Design: Saliva samples were collected from 24 healthy young males and 26 females by the spitting method while chewing paraffin and the CWSFRs were measured. UWSFR and the estimated sizes of the three major salivary glands in our previous study were used., Results: The CWSFRs in all subjects and in males correlated positively with UWSFR, but not in females. The CWSFRs in all subjects correlated positively with parotid and/or submandibular gland sizes, weights and body mass indices, just as with UWSFR; however, the correlation coefficients with salivary gland sizes were smaller than those of UWSFR. In contrast to the results of UWSFR, the correlation coefficients of the CWSFRs with parotid gland sizes in all subjects were larger than those with the sizes of the submandibular glands. The CWSFRs in males correlated only with parotid gland sizes, and those in females did not correlate with any of the parameters., Conclusions: The results suggest that the larger the size of the salivary glands, the greater the CWSFR, at least in males.

Objective: A gender difference in the unstimulated whole saliva flow rate (UWSFR) may be due to a difference in the sizes of the salivary glands. In this study, we investigated the relationships among the UWSFR, gland sizes and body sizes of healthy young adult males and females., Design: Unstimulated whole saliva was collected for 5 min by the spitting method in 50 healthy young adults, and the flow rate of the saliva was measured. Heights and weights were measured, and body mass indices (BMI) were calculated. The sizes of the salivary glands were measured by use of a magnetic resonance imaging technique., Results: Parotid and submandibular gland sizes and flow rates in females were significantly smaller than those in males, as were also the weights, heights and BMI. In both males and females, there were significant positive correlations between gland sizes and the flow rates, weights and BMI. The variations of the flow rates were reduced by standardizing them with gland sizes, weights and BMI., Conclusions: These results suggest that the lower UWSFR in females as compared with males is due to the smaller gland sizes due to the smaller body sizes.

Objective: The aim of this study was to examine the relationships between gland sizes and the flow rate and composition of the unstimulated whole saliva in humans., Design: In 28 healthy young adults, the sizes of the three major salivary glands were estimated by use of a magnetic resonance (MR) imaging technique. Unstimulated whole saliva was collected for 5 min by the spitting method, and the flow rate and the concentrations of total protein, Na(+) and K(+) and pH were measured., Results: The estimated sizes of the parotid and submandibular glands showed a significant positive correlation with the flow rate and the secretion rate of total protein in the unstimulated whole saliva, but that of the sublingual glands did not. Concerning the concentrations of Na(+) and K(+) and pH, there were no correlations with the salivary gland sizes., Conclusions: The results suggest that the larger the sizes of the parotid and submandibular glands, the faster the fluid flow and protein secretion rates in unstimulated whole saliva.

Both the Ca(2+)-releasing mechanism induced by cyclic ADP-ribose (cADPR) and the ADP-ribosyl cyclase (ADPRC) activity that converts NAD(+) to cADPR were observed in a variety of cell types. We studied the ADPRC activity in rat major salivary glands that include parotid gland (PG), submandiblar gland (SMG), and sublingual gland (SLG). The enzyme activity responsible for cADPR synthesis was detected by spectrofluorometric assay using NGD(+) as a substrate. The enzyme activities in SLG, SMG, and PG were about 400, 30, and 40 nmol/min/g tissue, respectively, in 5-week-old rats. The highest value was observed in SLG and this value was higher than those in other tissues; e.g., spleen (200 nmol/min/g tissue). The enzyme activity in SLG increased gradually after birth and showed a maximum value at 3 weeks. On the other hand, the enzyme activities almost did not change in both PG and SMG between 0 and 9 weeks. In spite of the high ADPRC activity in SLG, we could not detect the cADPR-induced Ca(2+)-release from SLG microsomes. These results suggest that the ADPRC in SLG does not function through Ca(2+)-release observed in various tissues., (Copyright 2000 Academic Press.)