title: Role of pH gradient and membrane potential in dipeptide transport in intestinal and renal brush-border membrane vesicles from the rabbit. Studies with L-carnosine and glycyl-L-proline.
abstract: We examined the role of pH gradient and membrane potential in dipeptide transport in purified intestinal and renal brush-border membrane vesicles which were predominantly oriented right-side out. With an intravesicular pH of 7.5, changes in extravesicular pH significantly affected the transport of glycyl-L-proline and L-carnosine, and optimal dipeptide transport occurred at an extravesicular pH of 5.5-6.0 in both intestine and kidney. When the extravesicular pH was 5.5, glycyl-L-proline transport was accelerated 2-fold by the presence of an inward proton gradient. A valinomycin-induced K+ diffusion potential (interior-negative) stimulated glycyl-L-proline transport, and the stimulation was observed in the presence and absence of Na+. A carbonyl cyanide p-trifluoromethoxyphenylhydrazone-induced H+ diffusion potential (interior-positive) reduced dipeptide transport. It is suggested that glycyl-L-proline and proton(s) are cotransported in intestinal and renal brush-border membrane vesicles, and that the process results in a net transfer of positive charge.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002336:Carnosine / Q000378:metabolism*; D004151:Dipeptides / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000648:ultrastructure*; D007668:Kidney / Q000648:ultrastructure*; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D004151:Dipeptides; D014634:Valinomycin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C015248:glycylproline; D002336:Carnosine; D011188:Potassium