Hollander D, Rim E, Muralidhara K S
Gastroenterology. 1975 Jun;68(6):1492-9.
The site and mechanism of alpha-[5-methyl-3-H]tocopherol absorption was investigated using everted rat small bowel sacs incubated in a micellar medium. Mean plus or minus SE absorption rates of the vitamin at 300 muM incubation solution concentration by proximal, medial, and distal small bowel segments were 2.2 plus or minus 0.17, 3.4 plus or minus 0.21, and 2.0 plus or minus 0.04 nmoles per min per 100 mg, respectively. Addition of 2,4-dinitrophenol, sodium azide, or potassium cyanide to the incubation medium in separate experiments did not change the rate of absorption (P greater than 0.10). Stepwise increase in incubation solution tocopherol concentration up to 1200 muM resulted in a linear increase in the absorption rate. In all of the above described experiments the rate of absorption of the vitamin by the medial portion of the small bowel was significantly (P smaller than 0.01) higher than the rate of absorption of the vitamin by the proximal and distal small bowel segments. No transmural transport of the vitamin into the serosal compartment took place. Autoradiographic examination of the tissue after incubation disclosed accumulation of the vitamin in the submucosal lymphatic spaces. Alpha-Tocopherol absorption by the rat small bowel appears to be a passive diffusion process taking place at the highest rate in the medial portion of the small bowel.
利用外翻大鼠小肠囊在胶束介质中孵育，研究了α-[5-甲基-³H]生育酚的吸收部位和机制。在300μM孵育溶液浓度下，近端、中段和远端小肠段对该维生素的平均吸收速率（均值±标准误）分别为每100mg每分钟2.2±0.17、3.4±0.21和2.0±0.04纳摩尔。在单独的实验中，向孵育介质中添加2,4-二硝基苯酚、叠氮化钠或氰化钾均未改变吸收速率（P＞0.10）。将孵育溶液中生育酚浓度逐步提高至1200μM，吸收速率呈线性增加。在上述所有实验中，小肠中段对该维生素的吸收速率显著高于近端和远端小肠段（P＜0.01）。未发生维生素向浆膜腔的跨壁转运。孵育后对组织进行放射自显影检查发现，维生素在黏膜下淋巴间隙中蓄积。大鼠小肠对α-生育酚的吸收似乎是一个被动扩散过程，在小肠中段的发生速率最高。
