Article: article from journal or magazin.
Differential effects of (D)- and (L)-homocysteic acid on the membrane potential of cat caudate neurons in situ.
Publication types: Journal ArticlePublication Status: ppublish
The enantiomers of homocysteic acid have been applied by microiontophoresis to neurons of the cat caudate nucleus in situ. The (L)-enantiomer elicited a bursty firing pattern similar to the one caused by N-methyl-D-aspartate, but differing from the N-methyl-D-aspartate pattern inasmuch as (L)-homocysteate induced depolarization shifts were shorter and had a smaller amplitude. (L)-Homocysteate induced excitations could be strongly inhibited by the selective N-methyl-D-aspartate antagonist 2-amino-7-phosphonoheptanoic acid but they were less sensitive to this antagonist than N-methyl-D-aspartate itself. (D)-Homocysteate elicited a more regular firing pattern similar to the one caused by non-N-methyl-D-aspartate excitatory amino acids such as quisqualate. These excitations were only rarely inhibited by 2-amino-7-phosphonoheptanoic acid. Our results suggest that (L)-homocysteate, a transmitter candidate at central mammalian synapses, is a mixed excitatory amino acid agonist with a strong preference for N-methyl-D-aspartate receptors in the cat caudate nucleus, while (D)-homocysteate has a predominant action at non-N-methyl-D-aspartate excitatory amino acid receptors.
2-Amino-5-phosphonovalerate/analogs & derivatives, Action Potentials/drug effects, Amino Acids/pharmacology, Animals, Cats, Caudate Nucleus/drug effects, Caudate Nucleus/physiology, Female, Homocysteine/analogs & derivatives, Homocysteine/pharmacology, Male, Membrane Potentials/drug effects, Receptors, N-Methyl-D-Aspartate, Receptors, Neurotransmitter/drug effects, Receptors, Neurotransmitter/physiology, Stereoisomerism
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