Ionic dependence of glycylsarcosine uptake by isolated chicken enterocytes.
Dipeptide transport was studied in chicken enterocytes and its properties compared with those of Na+-dependent sugar transport. Results showed that 1) isolated cells were capable of accumulating glycylsarcosine (Gly-Sar) against a concentration gradient (2.5- to 3.0-fold accumulation). This uptake was maximal at pH 6.0, and it was inhibited by Na+-free medium and by ouabain; 2) uptake of Gly-Sar was not affected by methionine and was competitively inhibited by carnosine, with a Ki of 12 mM; 3) the protonophore FCCP inhibited both Gly-Sar and 3-oxy-methyl-D-glucose (3-OMG) uptake by the cells; 4) amiloride, a well-known inhibitor of the Na+/H+ exchanger system stimulated 3-OMG uptake and inhibited Gly-Sar uptake, its effects being greater at pH 7.4; 5) and monensin prevents the effects of amiloride on both sugar and dipeptide uptake. In summary, Gly-Sar uptake depends on extracellular Na+ in an indirect manner via its effect on H+ efflux, and it appears to be dependent on an inward H+ gradient.
Calonge
M L
ML
Department of Physiology, Pharmacy Faculty, University of Seville, Spain.
Ilundain
A
A
Bolufer
J
J
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002336:Carnosine / Q000494:pharmacology; D002352:Carrier Proteins / Q000502:physiology*; D002645:Chickens; D004151:Dipeptides / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008757:Methylglucosides / Q000378:metabolism; D008985:Monensin / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D004151:Dipeptides; D008757:Methylglucosides; D017923:Sodium-Hydrogen Exchangers; C004194:glycylsarcosine; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000584:Amiloride; D002336:Carnosine; D008985:Monensin; D012964:Sodium