title: Descending fibre-mediated release of endogenous glutamate and glycine from the perfused cat spinal cord in vivo.
abstract: The release of endogenous amino acids into the perfused central canal of the cat spinal cord in vivo was studied using a [3H]dansyl chloride assay procedure. Perfusion of 0.1 mM p-chloromercuriphenyl-sulphonate (pCMS), an uptake inhibitor, augmented the efflux of most amino acids studied. The large increases in glycine, glutamate and GABA efflux (9.9, 5.3 and 4.1-fold, respectively) suggest that the membrane fluxes of these amino acids were particularly high, a finding consistent with their putative neurotransmitter functions. Subsequent electrical stimulation of descending spinal tracts increased the efflux of glycine, glutamate, GABA and leucine (1.8, 2.2, 1.9 and 1.3-fold, respectively), although only the release of glycine and glutamate was clearly independent of the concomitant rise in blood pressure. The evoked amino acid release, which was accompanied by a substantial ventral root discharge, was not observed in the absence of pCMS, nor in the presence of a low concentration (0.01 mM) of this compound. These results have been discussed in relation to the putative neurotransmitter roles for amine acids in the spinal cord.
authors.affiliation: Department of Pharmacology, University College London, London WC1E 6BT, Great Britain.
authors.forename: G E
authors.initials: GE
authors.lastname: Fagg
authors.forename: C C
authors.initials: CC
authors.lastname: Jordan
authors.forename: R A
authors.initials: RA
authors.lastname: Webster
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002415:Cats; D003619:Dansyl Compounds / Q000378:metabolism; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D008297:Male; D010477:Perfusion / Q000379:methods; D013116:Spinal Cord / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D003619:Dansyl Compounds; D004791:Enzyme Inhibitors; D014316:Tritium; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D002731:4-Chloromercuribenzenesulfonate; C029038:dansyl chloride; D005998:Glycine