ISSN:
1432-1351
Keywords:
Electroreceptors
;
Lorenzinian ampulla
;
Afferent synapse
;
Neurotransmitters
;
Pharmacology
;
Amino acid antagonists
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. The effects of excitatory amino acid antagonists on synaptic transmission in the ampullae of Lorenzini of the skate Raja clavata were studied. 2. At concentrations of 10-3 to 10-6 M, l-glutamic acid diethylester (GDEE) and l-glutamic acid dimethylester (GDME) decreased the resting afferent discharge frequency as well as the electrically evoked activities and depressed the responses to application of excitatory amino acids. 3. d-α-Aminoadipic acid (AA) and 2-amino-4 phosphonobutyric acid (APB) had practically no effect either on resting afferent discharge or on evoked afferent activity. 4. 2-Amino-5-phosphonovaleric acid (APV) reduced the resting afferent discharge and electrically evoked activity in the afferent fibres. APV blocked N-methyl-d-aspartate (NMDA) induced responses at a lower concentration than those induced by aspartate. 5. Responses caused by NMDA were Mg2+-dependent; those to quisqualate (Q) application depended to a lesser degree on the Mg2+ concentration. 6. Cis-2,3-piperidinedicarboxylic acid (PDA) blocked both the resting afferent discharge and the electrically evoked activity; it also reversibly blocked the postsynaptic, amino acid-induced responses. The l-glutamate (l-GLU) response was more resistant to the blockade than the l-aspartate (l-ASP) response. 7. Both kynurenic acid (KEN) and γ-d-glutamylglycine (DGG) reduced the resting and evoked activities in the afferent fibres. l-ASP was more resistant to blockade by KEN than l-GLU. 8. These observations suggest a prominent physiological role of quisqualate-, kainate- and NMDA-preferring receptors in the ampullae of Lorenzini of Raja clavata.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00224355
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