McNee S G, Geddes D A, Weetman D A
Arch Oral Biol. 1982;27(11):975-9. doi: 10.1016/0003-9969(82)90106-6.
Using a clearance technique, diffusion coefficients, D, were measured in plaque samples in which metabolic activity was eliminated by fixation with glutaraldehyde. Diffusion coefficients for sucrose, sodium acetate and sodium lactate at 37 degrees C were 3.0, 5.0 and 4.8 x 10(-6) cm2 s-1, respectively. Diffusion rate in plaque was between 2- and 5-fold slower than in water with uncharged species retarded less than charged species. However, diffusion in thin layers of plaque (100 microns) was rapid with clearance-halving times. T1/2, of about 6 s for acetate and lactate and 9 s for sucrose. Acetic and lactic acids diffuse faster than sucrose in plaque. Thus, the prolonged lowering of plaque pH following exposure to dietary carbohydrate is due to continued acid production in the plaque rather than to a restriction of diffusion of acid.
采用间隙技术，在通过戊二醛固定消除代谢活性的菌斑样本中测量扩散系数D。37℃时蔗糖、醋酸钠和乳酸钠的扩散系数分别为3.0、5.0和4.8×10⁻⁶ cm² s⁻¹。菌斑中的扩散速率比水中慢2至5倍，不带电荷的物质比带电荷的物质受阻小。然而，在薄层菌斑（100微米）中扩散很快，醋酸盐和乳酸盐的清除半衰期T1/2约为6秒，蔗糖为9秒。在菌斑中，乙酸和乳酸比蔗糖扩散得更快。因此，接触膳食碳水化合物后菌斑pH值的持续降低是由于菌斑中持续产酸，而非酸扩散受限。
