High affinity uptake of transmitters: studies on the uptake of L-aspartate, GABA, L-glutamate and glycine in cat spinal cord.

摘要: — The uptake of l-aspartate, l-glutamate and glycine each appeared to be mediated by two kinetically distinct systems with apparent Km's the order 10 ('high affinity') 100 μM ('low in slices cat spinal cord, whereas GABA a single system high affinity. affinity these amino acids grey matter was approximately 5 times faster than that white matter. cord survived homogenisation tissue under conditions known preserve nerve terminals. Subcellular fractionation studies indicated osmotically-sensitive particles equilibrium density equivalent 1.0 m-sucrose were at least part responsible for acids. Inhibition three structurally specific transported acids: 1 specific glycine—not inhibited or any other depressant found cord; 2 specific GABA—not glycine, taurine, l-aspartate (3) l-glutamate—not but strongly various acidic such as l-cysteate l-cysteine sulphinate. The not antagonists postsynaptic actions acids—strychnine (glycine), bicuculline benzyl penicillin (GABA), methioninesulphoximine diethyl ester (l-aspartate l-glutamate). p-Chloromercuriphenylsulphonate much less effective an inhibitor l-aspartate/l-glutamate uptake. This is good agreement microelectrophoretic which this mercurial potentiate depression neuronal firing induced more readily excitation l-glutamate. These findings suggest importance transport processes removal from synaptic environment.