齧歯類顎下腺唾液のCaとPiの動態
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概要
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The concentrations of calcium (Ca) and inorganic phosphate (Pi) are very important to evaluate dental caries and periodontal diseases. This work was, thus, designed to determine changes of the concentrations of Ca and Pi and the ratios of Ca/ Pi in submandibular saliva of rats and hamsters collected at the different time of the day, in response to various sialogogues at different doses with and without autonomic antagonists and a Ca ion-channel blocker. In addition, the effects of calculogenic diet RC-16,given for 2,3 and 5 weeks, on these three parameters in rat submandibular saliva in response to isoproterenol (IPR) were also determined atomic absorption spectroscopically and color spectroscopically. Calculus-like substances were also observed by scanning electron microscopy (SEM) and electron probe microscopical analysis (EPMA). The Ca concentration in submandibular salivas of rats and hamsters in response to different types of sialogogues was significantly higher in IPR-stimulated saliva than in other sialogogues and then in both α_1- and β_1-adrenoceptor-stimulated saliva was follwed, whereas in α_1-adrenergic, cholinergic and peptidergic stimuli, it was the lowest in all sialogogues. However, the Pi concentration was vice versa. The Ca and Pi concentrations in salivas were different at the time of the day collected and were significantly higher at 5 p.m. than those at 9 a.m. in several salivas elicited by various sialogogues, whereas they were dependent or independent upon the doses of sialogogues used depending upon the nature of the stimulus. The Ca concentration was significantly reduced in combination with propranolol and phenoxybenzamine, and the Pi concentration was significantly reduced with phenoxybenzamine, but not other autonomic blockers in response to substance P. The Ca, but not Pi, concentration in salivas in response to various secretagogues was markedly reduced in combination with a Ca ion-channel blocker, although in IPR-stimulated saliva it was the highest in other salivas. The Ca concentration and Ca/Pi ratios, but not the Pi concentration, in rodent submandibular salivas, in general, were positively correlated to the protein concentration and total output of protein secreted, whereas they were inversely related to salivary flow rates. Calculus formation was occurred in the 2- to 5-week groups fed with calculogenic diet RC-16. The Ca and Pi concentrations did not significantly change in the 2- and 3-week groups but in the 5-week groups significantly increased when compared to those of controls. Total phosphate was actively incorporated into calculus-like substances at early stages, whereas total calcium was actively incorporated into only at the 5-week group by elucidating with EPMA. These results suggest that the high Ca concentration and high Ca/Pi ratios, but not the high Pi concentration, in submandibular saliva of rodents are positively correlated to the high protein concentration and high total output of protein secreted in almost all experimental coditions and that in rodents the high Pi concentration is more important for the initial calcification process than that of Ca.
- 福岡歯科大学学会の論文
- 1996-09-30