Effects of L-cysteine-sulphinate and L-aspartate, mixed excitatory amino acid agonists, on the membrane potential of cat caudate neurons.
Responses evoked by L-cysteine-sulphinate (L-CSA) and L-aspartate (L-Asp) were recorded with intracellular electrodes from caudate neurons in halothane anesthetized cats. L-CSA and L-Asp were applied microiontophoretically to caudate cells and their effects on membrane and action potentials, as well as on cortically evoked synaptic potentials were evaluated. L-CSA and L-Asp induced depolarizations accompanied by regular firing resembling kainate (KA)- or quisqualate (QUIS)-induced excitation patterns (type 1) in 82% and 72% of the recorded neurons, respectively, and a mixed pattern consisting of a N-methyl-D-aspartate (NMDA)-like excitation (type 2) followed by a regular type 1 pattern in the remaining cells. In about a quarter of the cells the effects of L-CSA and L-Asp, but not those of KA or QUIS, were partially antagonized by 2-amino-7-phosphonoheptanoate (AP-7), a specific NMDA receptor antagonist. Kynurenate, a broad spectrum excitatory amino acid antagonist, blocked responses elicited by either L-CSA or QUIS. The actions of L-CSA and L-Asp on the firing pattern and membrane potential of cat caudate neurons in situ provide evidence in favor of their mixed agonist nature with respect to NMDA and non-NMDA excitatory amino acid receptors.
Turski
W A
WA
Herrling
P L
PL
Do
K Q
KQ
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives*; D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects* / Q000502:physiology; D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate; D018377:Neurotransmitter Agents; D010069:Oxadiazoles / Q000494:pharmacology; D016318:Quisqualic Acid
D000596:Amino Acids; D018377:Neurotransmitter Agents; D010069:Oxadiazoles; D001224:Aspartic Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D016318:Quisqualic Acid; D003545:Cysteine; C031231:2-amino-7-phosphonoheptanoic acid; D007608:Kainic Acid; C013461:cysteine sulfinic acid