Effects of acromelic acid A on the binding of [3H]-kainic acid and [3H]-AMPA to rat brain synaptic plasma membranes.

Article date: 1992/1/1

PubMed ID: 2155495

Journal name: British journal of pharmacology (ISSN: 0007-1188)


1. The ability of acromelic acid A to inhibit [3H]-kainic acid and [3H]-(RS)-alpha-amino-3-hydroxy-5-methyloxazole-4-propionic acid ([3H]-AMPA) binding to rat brain synaptic plasma membranes was investigated by equilibrium radioligand binding assay. 2. Kinetic analysis of [3H]-kainic acid binding demonstrated the existence of two kainate binding sites in this tissue preparation and yielded equilibrium dissociation constants for [3H]-kainic acid of KD = 0.4 nM and KD = 20.8 nM. 3. Kainic acid and domoic acid both appeared to displace [3H]-kainic acid from a single binding site with equilibrium binding constants of KD = 19.4 nM and Ki = 14.5 nM respectively. Acromelic acid A exhibited a biphasic inhibition of [3H]-kainic acid binding to synaptic membranes with binding affinities of Ki = 15.1 nM and Ki = 1.49 microM. 4. In the absence of chaotropic ions, the order of potency of inhibition of [3H]-AMPA binding was acromelic acid A (Ki = 26 nM) greater than AMPA (KD = 184 nM) greater than domoic acid (Ki = 499 nM). 5. The inclusion of 100 mM thiocynanate ion in the [3H]-AMPA binding assay resulted in a change in the order of potency to: AMPA (KD = 160 nM) greater than acromelic acid A (Ki = 289 nM) greater than domoic acid (Ki = 9.02 microM). 6. These results show that acromelic acid A distinguishes two kainate binding sites in rat brain synaptic plasma membranes and in addition, that in the absence of chaotropic ions, acromelic acid A is the most potent displacer of [3H]-AMPA binding yet described.

Author List: Smith A L, McIlhinney R A

Publication Types: Journal Article

Substances mentioned in the article: Quinolines; alpha-pentyl-3-(2-quinolinylmethoxy)benzenemethanol; Ibotenic Acid; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; acromelic acid A; Kainic Acid;

Mesh terms: Animals; Brain/drug effects; Female; Ibotenic Acid/analogs & derivatives; Kainic Acid/analogs & derivatives; Kinetics; Quinolines/pharmacology; Radioligand Assay; Rats; Rats, Inbred Strains; Synaptic Membranes/drug effects; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

Citations: - 492142

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