title: Chloride dependence of the sodium-dependent glycine transport in pig kidney cortex brush-border membrane vesicles.
abstract: The Na+-dependent glycine uptake in pig kidney cortex brush-border membrane vesicles is specifically enhanced by the presence of Cl-. The Na+-independent glycine uptake is not affected by Cl-. Various anions tested could not substitute Cl- in the activation of the Na+-dependent glycine transport. Cl- is specifically required on the outer membrane side. The Na+-dependent glycine uptake is higher in the presence of an inwardly directed Cl- gradient than the one measured in the presence of equilibrated Cl-. The Na+-dependent glycine uptake depends on, and is saturable at increasing Cl- concentrations. By studying the activation of glycine uptake by Na+ in the presence and in the absence of Cl-, evidence was found that two different Na+-dependent glycine transport pathways are present in pig kidney cortex brush-border membrane vesicles. The kinetics of the glycine uptake measured in the presence of an inwardly directed NaCl gradient show the presence of two glycine transport systems, a low-affinity, high-capacity one and a high-affinity, low capacity one. In the absence of Cl- the high-affinity, low-capacity transport is almost suppressed, thus indicating the presence of a high-affinity glycine transport system simultaneously dependent on both Na+ and Cl- ions.
mesh_terms: D000818:Animals; D000838:Anions; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000494:pharmacology*; D005998:Glycine / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology*; D013552:Swine; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D000838:Anions; D002712:Chlorides; D014634:Valinomycin; D012964:Sodium; D005998:Glycine