Guiraldes E, Sanhueza P, Palma R, Orrego H
Acta Physiol Lat Am. 1979;29(4-5):229-37.
The relationship between changes in intestinal lactase activity and monosaccharide uptake was studied in rats of different ages using the technique of intestinal everted sacs. In the postweaning period there is a sharp decrease in the rate of glucose and galactose uptake by the small intestinal mucosa. This change occurs simultaneously with a decrease in lactase activity in the tissue. The kinetic analysis showed a lower Vmax for monosaccharide uptake in the 50-days-old rats as compared with the fifteen-days-old animals, with no change in the apparent Kt. The addition of Tris+ (40 mM) to the incubation media was found to produce a decrease in Vmax for monosaccharide uptake only in the suckling rats but not in the 50-days-old animals; the K1 remained unchanged. Tris+, at the concentration used had previously been shown to completely inhibit lactase activity in homogenates of small intestinal mucosa. These observations lead us to postulate the lactase in the suckling rat might possess a translocating role for sugar, in addition to its hydrolytic function. The decrease in sugar uptake after weaning could be explained by the disappearance of this role.
利用肠外翻囊技术，研究了不同年龄大鼠肠道乳糖酶活性变化与单糖摄取之间的关系。在断奶后时期，小肠黏膜对葡萄糖和半乳糖的摄取速率急剧下降。这种变化与组织中乳糖酶活性的降低同时发生。动力学分析表明，与15日龄动物相比，50日龄大鼠单糖摄取的Vmax较低，表观Kt无变化。发现向孵育培养基中添加Tris⁺（40 mM）仅在乳鼠中会导致单糖摄取的Vmax降低，而在50日龄动物中则不会；K1保持不变。先前已表明，所用浓度的Tris⁺可完全抑制小肠黏膜匀浆中的乳糖酶活性。这些观察结果使我们推测，乳鼠中的乳糖酶除了具有水解功能外，可能还具有转运糖类的作用。断奶后糖摄取的减少可以用这种作用的消失来解释。
