[Effects of a new excitotoxic amino acid, dysiherbaine, on cultured Müller cells].
OBJECTIVE
To determine pharmacological response of dysiherbaine on cultured Müller cells considering the glutamate receptor functions. Dysiherbaine is a new excitotoxic amino acid, which was recently isolated from the water extract of a certain sponge.


METHODS
Retinas of adult rabbits were used to prepare the Müller cells. Intracellular calcium ion concentration ([Ca2+]i) analysis was done by fluorophotometry with calcium indicator, Fura-2 AM.


RESULTS
A transient increase of [Ca2+]i was observed following the administration of dysiherbaine (2.5 microM -2.5 mM), but it was not observed in the extracellular calcium-free solution. This increase was blocked by the non NMDA glutamate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). A dysiherbaine-induced increase in [Ca2+]i following preincubation of the NMDA glutamate receptor antagonist, (5 R, 10 S)-(+)-5-methyl-10, 11-dihydro-5 H-dibenzo [a, d] cyclohepten-5, 10-imine hydrogen maleate (MK 801) was seen in the same number of Müller cells as without the antagonist.


CONCLUSIONS
Dysiherbaine appears to act primarily as a non NMDA glutamate receptor agonist having a secondary action as a NMDA glutamate receptor agonist.
Minei
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Department of Ophthalmology, Kitasato University, School of Medicine, Sagamihara, Japan.
D000409:Alanine / Q000031:analogs & derivatives*; D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D006574:Heterocyclic Compounds, 2-Ring / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology*; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D000596:Amino Acids; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018690:Excitatory Amino Acid Agonists; D006574:Heterocyclic Compounds, 2-Ring; D009498:Neurotoxins; C121741:dysiherbaine; D000409:Alanine; D002118:Calcium