Rose R K, Dibdin G H
MRC Dental Group, Dental School, Bristol, U.K.
Arch Oral Biol. 1995 May;40(5):385-91. doi: 10.1016/0003-9969(94)00188-h.
The diffusion of tritiated water and 45Ca through single-species model plaques was measured in a diaphragm cell. Using plaques of Streptococcus downei, the apparent diffusion coefficient for tritiated water showed a small but significant decrease between pH 7.0 and 5.0 with a smaller, non-significant decrease for calcium. These effects are attributed to possible plaque shrinkage at reduced pH, which overcomes effects due to charge-dependent changes in permeability. Effective diffusion coefficients for 45Ca obtained from lag-time measurements were much reduced at low carrier concentrations, demonstrating a binding which correlated with previous results from equilibrium dialysis. Strep. sanguis and Corynebacterium matruchotii showed few differences from Strep. downei, although the corynebacterium previously demonstrated stronger calcium binding. Permeability to water and calcium were slightly affected by pH, while effective diffusion of calcium depended on concentration. This may have important implications for the process of mineral loss in dental caries.
在隔膜池中测量了氚化水和45Ca通过单菌种模型菌斑的扩散情况。使用唐氏链球菌菌斑，氚化水的表观扩散系数在pH 7.0至5.0之间呈现出虽小但显著的下降，而钙的下降幅度较小且不显著。这些影响归因于在较低pH值下菌斑可能发生的收缩，这克服了由于通透性的电荷依赖性变化所产生的影响。通过滞后时间测量获得的45Ca的有效扩散系数在低载体浓度下大幅降低，表明存在一种结合，这与先前平衡透析的结果相关。血链球菌和啮蚀艾肯菌与唐氏链球菌相比差异不大，尽管之前已证明艾肯菌具有更强的钙结合能力。水和钙的通透性受pH值的影响较小，而钙的有效扩散取决于浓度。这可能对龋齿中矿物质流失的过程具有重要意义。
