大鼠空肠外翻肠段对叶酸的吸收
Absorption of folic acid by everted segments of rat jejunum.
作者信息
Blair J A, Johnson I T, Matty A J
出版信息
J Physiol. 1974 Feb;236(3):653-61. doi: 10.1113/jphysiol.1974.sp010458.
Abstract
- Everted rings of rat intestine were used to study the initial uptake rate of folic acid at various concentrations and incubation temperatures in vitro.2. Folic acid was accumulated linearly for periods of at least 30 min.3. The initial uptake rate was found to reach a constant value as the concentration of folic acid in the incubation medium was increased above 5 x 10(-6)M.4. Reducing the temperature of incubation from 37 to 27 degrees C gave small Q(10) values at either end of the concentration range.5. Transfer of folic acid into the serosal compartment of everted sacs was shown to undergo a rate reduction in the same concentration range.6. A mechanism for folic acid transport is suggested in which folic acid is converted to the neutral species at the mucosal surface in an acid microclimate.
摘要
采用大鼠肠外翻环来研究体外不同浓度和孵育温度下叶酸的初始摄取率。
叶酸至少在30分钟内呈线性积累。
当孵育培养基中叶酸浓度增加到高于5×10⁻⁶M时，初始摄取率达到恒定值。
将孵育温度从37℃降至27℃，在浓度范围的两端都得到较小的Q₁₀值。
结果表明，在相同浓度范围内，叶酸向肠外翻囊浆膜腔的转运速率降低。
提出了一种叶酸转运机制，即在酸性微环境中，叶酸在黏膜表面转化为中性形式。
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