Transport of selenate and sulphate across the intestinal brush-border membrane of pig jejunum by two common mechanism.
The objectives of the present study were to find out whether selenate and sulphate are transported by a common Na+-dependent transport mechanism across the intestinal brush-border membrane and whether selenate is also transported by the anion-exchange system transporting sulphate across the brush-border membrane. Results from cis-inhibition as well as from trans-stimulation experiments show that selenate and sulphate are transported across the brush-border membrane by both Na+ co-transport and anion exchange. The influence of various dicarboxylates (oxalate, oxaloacetate, glutamate) and of the anion-exchange inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulphonate (DIDS) on selenate and sulphate transport across the brush-border membrane was also investigated. Under Na+-gradient conditions selenate uptake across the brush-border membrane was reduced by oxalate and oxaloacetate but not by L-glutamate or L-leucine. Additionally sulphate uptake under this condition was significantly inhibited by oxalate (about 50%) and DIDS (25%). Sulphate transport by anion exchange was inhibited about 80% by both oxalate and DIDS. These results suggest that under Na+-gradient conditions sulphate (selenate) uptake in part occurs via anion exchange. Furthermore, oxalate seems to inhibit both Na+-sulphate (selenate) co-transport and sulphate (selenate) transport by anion exchange.
Wolffram
S
S
Institut für Veterinär-Physiologie, Universität Zürich, Switzerland.
Grenacher
B
B
Scharrer
E
E
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; D001693:Biological Transport, Active / Q000187:drug effects; D003998:Dicarboxylic Acids / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism / Q000494:pharmacology; D008871:Microvilli / Q000378:metabolism*; D010070:Oxalates / Q000494:pharmacology; D064586:Selenic Acid; D012643:Selenium / Q000378:metabolism*; D018036:Selenium Compounds; D013431:Sulfates / Q000378:metabolism*; D013552:Swine
D003998:Dicarboxylic Acids; D010070:Oxalates; D018036:Selenium Compounds; D013431:Sulfates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D007930:Leucine; D012643:Selenium; D064586:Selenic Acid; D005947:Glucose; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid