Anion transport in basolateral (sinusoidal) liver plasma-membrane vesicles of the little skate (Raja erinacea).
The mechanism(s) of [35S]sulphate transport was investigated in basolateral liver plasma-membrane vesicles of the little skate elasmobranch, Raja erinacea. Imposition of an intravesicular alkaline pH gradient (pH 8.0 in/pH 6.0 out) stimulated sulphate uptake 5-10-fold compared with pH-equilibrated (pH 8.0 in = out) conditions and 2-3-fold over equilibrium sulphate uptake (overshoot). This pH-gradient-stimulated sulphate uptake was temperature-dependent, saturable with increasing concentrations of sulphate and could be inhibited by the protonophore carbonyl cyanide m-chlorophenylhydrazone and the anion-transport inhibitors 4,4'-di-isothiocyanostilbene-2,2'-disulphonic acid (DIDS) and probenecid, cis-Inhibition of pH-gradient-driven sulphate uptake was observed with sulphate, oxalate, cholate and bromosulphophthalein, but not with chloride and taurocholate. In addition, sulphate and oxalate trans-stimulated [35S]sulphate uptake under pH-equilibrated conditions. Although also stimulated by an inside-alkaline pH gradient, transmembrane transport of [3H]cholate was not inhibited by DIDS, suggesting that its pH-gradient-driven uptake is not mediated by an anion-transport 'carrier'. In conclusion, these studies indicate that a basolateral plasma-membrane sulphate-transport system has evolved in skate hepatocytes and is similar to that in mammalian liver cells. This archaic anion-exchange system co-transports certain organic anions such as oxalate and has developed early in vertebrate evolution.
Mount Desert Island Biological Laboratory, Salsbury Cove, ME 04672.
G
G
Hugentobler
G
G
Fricker
J L
JL
Boyer
P J
PJ
Meier
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D019826:Cholic Acid; D002793:Cholic Acids / Q000493:pharmacokinetics; D004555:Electric Fish / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D011339:Probenecid / Q000494:pharmacology; D012860:Skates, Fish / Q000378:metabolism*; D013431:Sulfates / Q000493:pharmacokinetics*
D002793:Cholic Acids; D013431:Sulfates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D019826:Cholic Acid; D011339:Probenecid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid