Uptake of [(3)H]glycine by synaptosomes of channel.
It is known that channel catfish erythrocytes can take up glycine by several distinct transport systems. Further, glycine is an inhibitory neurotransmitter in mammalian brain and spinal cord. Consequently, the uptake of [(3)H]glycine by catfish brain was investigated and found to be a saturable process, dependent on the presence of Na(++) and Cl(--) and sensitive to temperature. A kinetic analysis of transport was performed at 22C. This showed that a high-affinity system existed which exhibited a K(m) of 5.1 (+/- 2. 1) microM. Several structural analogues of glycine were capable of inhibiting uptake in a competitive manner. The most effective inhibitor was sarcosine (IC(50) 5 36 microM). Uptake was also able to be inhibited by harmaline, a drug known to interfere with Na(+)-dependent transport processes. It is concluded that glycine transport by channel catfish brain has much in common with transport by mammalian nervous tissue which is carried out by the membrane carriers GLYT1 and GLYT2. On the other hand, synaptosomal transport differs somewhat from glycine transport by channel catfish erythrocytes.
Wolf
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Laboratory of Neurochemistry, Indiana University School of Medicine, Evansville, IN 47712, USA.
Lance
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Hart
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Tunnicliff
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D026921:Amino Acid Transport Systems, Neutral; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism; D005998:Glycine / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins; D007059:Ictaluridae / Q000378:metabolism*; D008322:Mammals / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012521:Sarcosine / Q000494:pharmacology; D013045:Species Specificity; D013574:Synaptosomes / Q000378:metabolism*; D013696:Temperature; D014316:Tritium / Q000032:analysis
D026921:Amino Acid Transport Systems, Neutral; D002352:Carrier Proteins; D004151:Dipeptides; D050487:Glycine Plasma Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D014316:Tritium; D005998:Glycine; D012521:Sarcosine