Biomaterial Database

Effects of excitatory amino acids and their antagonists on membrane and action potentials of cat caudate neurones. 1983

P L Herrling, and R Morris, and T E Salt

The electrical activity of caudate neurones was recorded with intracellular electrodes in halothane anaesthetized cats. Agonists and antagonists of excitatory amino acid receptors were applied by micro-ionophoresis and their effects on membrane- and action potentials and on cortically evoked synaptic potentials evaluated. The agonists, L-aspartate (asp), L-glutamate (glu), N-methyl-DL-aspartate (NMA), quinolinate and quisqualate all depolarized the membrane, caused repetitive firing, reduced the apparent amplitude of the cortically evoked excitatory post-synaptic potentials (e.p.s.p.s) and increased the amplitude of the associated inhibitory post-synaptic potential. Two of the agonists, NMA and quinolinate, additionally caused the appearance of up to 500 ms long depolarizations (plateaus) on the falling phase of action potentials. These plateaus were seen in about two-thirds of the cells in this sample while in the other third the excitatory effects of NMA and quinolinate were indistinguishable from those of glu and quisqualate. The N-methyl-D-aspartate (NMDA) receptor antagonist D-alpha-aminoadipate (DAA) reversibly inhibited the effects of NMA and quinolinate but only on those cells where these two agents evoked action potential plateaus while on the same cells the effects of asp, glu and quisqualate were either only weakly antagonized or not affected. On cells not displaying plateaus to NMA or quinolinate none of the effects of the agonists could be antagonized by DAA. DAA applications that completely antagonized the effects of NMA never reduced the amplitudes of cortically evoked e.p.s.p.s. Cis-2,3-piperidine dicarboxylate also blocked the effects of NMA and asp at low application currents while at higher currents it enhanced the effects of glu or asp although still retaining its NMA antagonistic activity. High-frequency stimulation of the cortico-caudate pathway resulted in long-lasting depolarizations and repetitive firing, but plateaus of the type caused by NMA or quinolinate were not seen.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D010069	Oxadiazoles	Compounds containing five-membered heteroaromatic rings containing two carbons, two nitrogens, and one oxygen atom which exist in various regioisomeric forms.	Oxadiazole
D010875	Pipecolic Acids		Acids, Pipecolic
D011805	Quinolinic Acids	Dicarboxylic acids with a PYRIDINE backbone. Quinolinic Acids are downstream products of the KYNURENINE pathway which metabolize amino acid TRYPTOPHAN.	Acids, Quinolinic
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D002421	Caudate Nucleus	Elongated gray mass of the neostriatum located adjacent to the lateral ventricle of the brain.	Caudatus,Nucleus Caudatus,Caudatus, Nucleus,Nucleus, Caudate
D005260	Female		Females
D005971	Glutamates	Derivatives of GLUTAMIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure.	Glutamic Acid Derivatives,Glutamic Acids,Glutaminic Acids