Transport of alpha-ketoisocaproate in neuroblastoma NB-2a cells.
Transport of alpha-ketoisocaproate (KIC), a ketoacid originating from leucine and proposed to be involved in the buffering of glutamate in neurones, was studied in neuroblastoma NB-2a cells. The accumulated KIC was mostly transaminated to leucine, while free keto-acid was detectable either only after prolonged times or after inhibiting transaminase with aminooxyacetate. Accumulation of KIC was found to be inhibited by other branched-chain ketoacids, while lactate and beta-hydroxybutyrate were ineffective. The transport of KIC, resembling a facilitated diffusion, was decreased by phloretin, alpha-cyano-4-hydroxycinnamate, 4,4'-diisothiocyano-2,2'-stilbenedisulphonate, and p-chlorimercuribenzoate. The process of accumulation did not resemble a symport with protons; therefore an involvement of the known proton-coupled monocarboxylate transporters (MCT) was excluded. Distribution of KIC suggests a mechanism involving a cotransport with 2 [Na+].
Bachowska-Mac
M
M
The Nencki Institute of Experimental Biology, Warsaw, Poland.
Nehlig
A
A
Nałecz
M J
MJ
Nałecz
K A
KA
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000625:Aminooxyacetic Acid / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002208:Caproates / Q000378:metabolism; D002264:Carboxylic Acids / Q000494:pharmacology; D002729:Chloromercuribenzoates / Q000494:pharmacology; D003373:Coumaric Acids / Q000494:pharmacology; D004058:Diffusion; D007651:Keto Acids / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008954:Models, Biological; D009447:Neuroblastoma / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010693:Phloretin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D020245:p-Chloromercuribenzoic Acid
D002208:Caproates; D002264:Carboxylic Acids; D002729:Chloromercuribenzoates; D003373:Coumaric Acids; D007651:Keto Acids; D000625:Aminooxyacetic Acid; C007175:alpha-cyano-4-hydroxycinnamate; D020245:p-Chloromercuribenzoic Acid; D010042:Ouabain; C013082:alpha-ketoisocaproic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D010693:Phloretin