Characteristics of Cl(-)-dependent L-[35S]cysteic acid transport into rat brain synaptic membrane vesicles.
Uptake of L-[35S]cysteic acid (L-CA) in rat synaptic membrane vesicles was investigated. Preincubation with either 10 mM L-glutamic acid (L-Glu), 25 mM L-CA, 10 mM DL-homocysteic acid, or 25 mM DL-2-amino-4-phosphonobutyrate on membrane vesicles enhanced L-[35S]CA and L-[3H]Glu uptake. Na+ (5 mM) and omission of Cl- from the assay medium decreased L-[35S]CA uptake into both 10 mM L-Glu-loaded and non-loaded membrane vesicles. The anion transport blockers, 4-acetamide-4'-isothiocyano-2,2'-disulfonic acid stilbene (SITS) and 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS), inhibited L-[35S]CA uptake in a dose-dependent manner. The maximal uptake rate for L-[35S]CA was decreased by 50 microM SITS, while the apparent Km value of L-CA was not changed. SITS increased the EC50 value of Cl- for L-[35S]CA uptake from 5 mM to 10 mM with reduction of the maximal effect. These results suggested that L-[35S]CA uptake into synaptic membrane vesicles was mediated by a SITS-sensitive hetero-exchange transport with non-labeled substrates.
Koyama
Y
Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Suita, Japan.
Baba
A
A
Iwata
H
H
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; D002540:Cerebral Cortex / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology*; D003544:Cysteic Acid / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D002712:Chlorides; D005971:Glutamates; D013654:Taurine; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D005680:gamma-Aminobutyric Acid; D003544:Cysteic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid