title: Sulfate transport by chick renal tubule brush-border and basolateral membranes.
abstract: Brush-border and basolateral membrane vesicles (BBMV and BLMV, respectively) were prepared from chick kidney by a calcium precipitation method and by centrifugation on an 8% Percoll self-generating gradient, respectively. In BBMV a 100-mM Na gluconate gradient, out greater than in, caused concentrative sulfate uptake approximately fivefold greater at 1 min than at 60 min (equilibrium) whether or not the membranes were short-circuited with 100 mM K gluconate, in = out, plus 20 micrograms valinomycin/mg protein. A 48-mM HCO3- gradient, in greater than out, stimulated a 2.5-fold higher uptake at 1 min than at 60 min, and short circuiting as above had no effect on the magnitude of this response. Imposition of a H+ gradient (pH 5.4 out vs. pH 7.4 in) caused concentrative uptake fourfold higher at 1 min than at equilibrium. Short circuiting as above or addition of 0.1 mM carbonyl cyanide m-chlorophenylhydrazone (CCCP) significantly inhibited the pH gradient effect. Creation of an inside positive electrical potential with 100 mM K gluconate, out greater than in, plus valinomycin, also caused concentrative sulfate uptake. The K gradient in the absence of valinomycin had no effect on sulfate uptake (compared with isosmotic mannitol). Based on inhibitor/competitor effects, these are distinct sulfate transport processes. In chick BLMV, imposition of an HCO3- gradient, in greater than out, produced concentrative sulfate uptake; however, neither Na+ nor H+ gradients had significant effects at 15 s. 4-Acetamido-4'-isothiocyanostilbene 2,2'-disulfonic acid disodium at 0.1 mM was an effective inhibitor of BLMV bicarbonate-sulfate exchange; however, neither Cl-, SCN-, nor CCCP inhibited.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002645:Chickens; D005260:Female; D005919:Glomerular Filtration Rate; D006863:Hydrogen-Ion Concentration; D007684:Kidney Tubules / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D013431:Sulfates; D013462:Sulfur Radioisotopes; D014634:Valinomycin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone