Scharrer E, Stubenhofer L, Tiemeyer W, Bindl C
Comp Biochem Physiol A Comp Physiol. 1984;77(1):85-8. doi: 10.1016/0300-9629(84)90016-1.
Pyrimidine absorption by chicken large intestine was investigated employing the everted sac and flux chamber techniques. 3H-labelled uracil was used as substrate. The small intestine and the colon unlike the caecum, transported uracil from the mucosal to the serosal surface against a concentration gradient in the everted sac experiments. Furthermore, there was a net transport of uracil from the mucosal to the serosal side of the colon and jejunum in the flux chamber experiments. Uracil transport by the everted colon sacs against a concentration gradient was inhibited when the purine hypoxanthine was present in the incubation medium. Uracil transport by the everted colon sacs was also inhibited under anaerobic conditions and when 2,4-dinitrophenol was present in the incubation medium. Replacing the Na+ ions of the incubation medium by Li+ ions also caused an inhibition of uracil transport. It is concluded from these results that uracil (and probably other pyrimidines) are absorbed from the chicken colon by a Na+ ion-dependent active transport process having also an affinity for purines.
采用外翻肠囊和通量室技术研究了鸡大肠对嘧啶的吸收。以3H标记的尿嘧啶作为底物。在外翻肠囊实验中，与盲肠不同，小肠和结肠将尿嘧啶逆浓度梯度从黏膜侧转运至浆膜侧。此外，在通量室实验中，尿嘧啶存在从结肠和空肠的黏膜侧到浆膜侧的净转运。当孵育介质中存在嘌呤次黄嘌呤时，外翻结肠囊对尿嘧啶的逆浓度梯度转运受到抑制。在厌氧条件下以及孵育介质中存在2,4-二硝基苯酚时，外翻结肠囊对尿嘧啶的转运也受到抑制。用锂离子替代孵育介质中的钠离子也会导致尿嘧啶转运受到抑制。从这些结果可以得出结论，尿嘧啶（可能还有其他嘧啶）通过一种依赖钠离子的主动转运过程从鸡结肠吸收，该过程对嘌呤也有亲和力。
