title: Active pyrimidine absorption by chicken colon.
abstract: 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.
mesh_terms: D019297:2,4-Dinitrophenol; D000042:Absorption; D000693:Anaerobiosis; D000818:Animals; D001692:Biological Transport; D002432:Cecum / Q000378:metabolism; D002645:Chickens / Q000378:metabolism*; D003106:Colon / Q000378:metabolism*; D004140:Dinitrophenols / Q000494:pharmacology; D005260:Female; D007042:Hypoxanthines / Q000494:pharmacology; D007583:Jejunum / Q000378:metabolism; D008297:Male; D011743:Pyrimidines / Q000378:metabolism*; D014018:Tissue Distribution; D014498:Uracil / Q000378:metabolism
chemical_list: D004140:Dinitrophenols; D007042:Hypoxanthines; D011743:Pyrimidines; D014498:Uracil; D019297:2,4-Dinitrophenol