Transport of L-valine by the chicken caecum.
1. We have studied L-valine transport by the caecal segments of 6- to 8-week-old chickens. Isolated enterocytes from the proximal caecum incubated with 0.1 mM L-valine can accumulate the substrate against a concentration gradient. After 50 min incubation, the intracellular L-valine concentration reached 0.53 mM, a value higher than that observed in enterocytes from the jejunum (0.34 mM; P< 0.01). 2. Enterocytes from the medial and distal caccal regions are unable to transport L-valine uphill (cell concentration: 0.1 mM). 3. Amino acid accumulation by proximal caecal cells was Na+ -dependent and was inhibited by ouabain and 2,4-dinitrophenol. L-methionine inhibits L-valine uptake and a 2.5 mM concentration abolishes the capacity of enterocytes to accumulate the substrate. 4. The high accumulation ratios shown by the proximal caecum for L-valine suggest a role for this intestinal segment in the absorption of neutral amino acids present in the caecal chamber.
Planas
J M
JM
Grup d'Absorció Intestinal, Facultat de Farmacià, Universitat de Barcelona, Spain.
González
E
E
Ferrer
R
R
Moretó
M
M
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002432:Cecum / Q000502:physiology*; D002478:Cells, Cultured; D002645:Chickens; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000502:physiology*; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D014633:Valine / Q000378:metabolism*
D010042:Ouabain; D012964:Sodium; D014633:Valine; D019297:2,4-Dinitrophenol