title: Uridine uptake by isolated intestinal epithelial cells of guinea pig.
abstract: Uptake of uridine was studied in isolated intestinal epithelial cells of guinea pig. Uptake was not severely influenced by metabolism. Free uridine was accumulated within cells 13-fold. Uptake was saturable with an apparent Km value of 46 microM and a Vmax of 0.9 nmol/mg protein per min. Uracil inhibited uptake only slightly; adenosine, guanosine and cytosine inhibited strongly. Antimycin A and ouabain inhibited almost 90%. If the extracellular Na+ concentration was decreased to 5 mM, the rate of uptake decreased 6.5-fold. The stimulatory effect of Na+ was related to the transmembraneous Na+-gradient. Cells from jejunum transported about 30% faster than cells from ileum. In conclusion, isolated enterocytes of guinea pig posses an active transport system for uridine.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002250:Carbon Radioisotopes; D003911:Dextrans; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D014316:Tritium; D014529:Uridine / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D003911:Dextrans; D014316:Tritium; D012964:Sodium; D011188:Potassium; D014529:Uridine