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The uptake of [ 14 C]glycine by slices of mammalian spinal cord
Author(s) -
Neal M. J.
Publication year - 1971
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1971.sp009460
Subject(s) - glycine , spinal cord , chemistry , neuroscience , biophysics , anatomy , biology , biochemistry , amino acid
1. The accumulation of [ 14 C]glycine by slices of mammalian spinal cord has been measured. 2. When slices of rat cord were incubated at 37° C in a medium containing [ 14 C]glycine, tissue:medium ratios of about 30:1 were attained after a 40 min incubation. 3. After incubations at 37° C for 40 min, almost all (98%) the radioactivity in the tissue was present as unchanged [ 14 C]glycine. 4. The process responsible for [ 14 C]glycine uptake showed many of the properties of an active transport system: it was temperature sensitive, required the presence of sodium ions in the external medium, was inhibited by dinitrophenol and ouabain and showed saturation kinetics. 5. The estimated K m value of glycine was 3·1 × 10 −5 M , and V max was 0·48 μ‐mole/min.g cord. 6. The uptake of [ 14 C]glycine was not affected by the presence of large molar excesses of L ‐histidine, L ‐proline, L ‐aspartate, L ‐glutamate, L ‐valine or GABA, but was inhibited in the presence of L ‐alanine and L ‐leucine. 7. The uptake of [ 14 C]glycine was not reduced by strychnine, but a significant reduction in uptake was produced by p ‐hydroxymercuribenzoate. 8. The uptake of [ 14 C]glycine by the grey matter of rabbit spinal cord was 2 to 6 times greater than the uptake by slices of white matter incubated under the same conditions. 9. Rat cerebral cortex, cerebellar cortex and medulla also accumulated [ 14 C]glycine, and the uptake by the tissue slices in vitro appeared to parallel the concentration of glycine in these areas in vivo . 10. It is suggested that the glycine uptake system may represent a possible mechanism for the inactivation of glycine at inhibitory synapses in the spinal cord.