Biomaterial Database

Ionotropic glutamate receptors in isolated horizontal cells of the rabbit retina. 1999

R Blanco, and P de la Villa

Department of Physiology, University of Alcalá de Henares, Spain.

With the use of the whole-cell voltage-clamp technique, we have recorded the currents induced by ionotropic glutamate receptor agonists on isolated axonless horizontal cells (HC) of rabbit retina. Bath application of the non-N-methyl-D-aspartate receptor agonists: kainate (KA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and L-glutamate (GLU) produced an increase in the conductance for non-selective cations. All the isolated horizontal cells responded to GLU, AMPA and KA. Responses elicited by GLU and AMPA but not KA exhibited a concentration-dependent desensitization. Application of N-methyl-D-aspartate (NMDA) evoked no responses. The rank order affinities of the agonists as estimated from EC50 values were AMPA > GLU > KA. Whereas KA had the lowest affinity of the agonists tested, it produced the largest currents. Hill coefficients of the concentration-response data were near 1 for AMPA, and 2 for KA and GLU. Coapplication of AMPA with cyclothiazide (CTZ) blocks AMPA receptor desensitization, and enhanced its effects on conductance. However, CTZ did not change the KA -induced conductances. In all cells tested, 6,7-dinitroquinoxaline (DNQX) completely and reversibly blocked the effects of KA and AMPA. The KA- and AMPA-induced currents were also completely blocked by 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466), a selective AMPA receptor antagonist. These results indicate that the responses to glutamate agonists in HC were mediated almost exclusively by AMPA receptors. Our study indicates that AMPA receptors play a fundamental role in mediating the synaptic input into rabbit horizontal cells.

UI	MeSH Term	Description	Entries
D007608	Kainic Acid	(2S-(2 alpha,3 beta,4 beta))-2-Carboxy-4-(1-methylethenyl)-3-pyrrolidineacetic acid. Ascaricide obtained from the red alga Digenea simplex. It is a potent excitatory amino acid agonist at some types of excitatory amino acid receptors and has been used to discriminate among receptor types. Like many excitatory amino acid agonists it can cause neurotoxicity and has been used experimentally for that purpose.	Digenic Acid,Kainate,Acid, Digenic,Acid, Kainic
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
D011810	Quinoxalines		Quinoxaline
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001569	Benzodiazepines	A group of two-ring heterocyclic compounds consisting of a benzene ring fused to a diazepine ring.	Benzodiazepine,Benzodiazepine Compounds
D014151	Anti-Anxiety Agents	Agents that alleviate ANXIETY, tension, and ANXIETY DISORDERS, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions. ADRENERGIC BETA-ANTAGONISTS are commonly used in the symptomatic treatment of anxiety but are not included here.	Anti-Anxiety Agent,Anti-Anxiety Drug,Anxiolytic,Anxiolytic Agent,Anxiolytic Agents,Tranquilizing Agents, Minor,Anti-Anxiety Drugs,Anti-Anxiety Effect,Anti-Anxiety Effects,Antianxiety Effect,Antianxiety Effects,Anxiolytic Effect,Anxiolytic Effects,Anxiolytics,Tranquillizing Agents, Minor,Agent, Anti-Anxiety,Agent, Anxiolytic,Agents, Anti-Anxiety,Agents, Anxiolytic,Agents, Minor Tranquilizing,Agents, Minor Tranquillizing,Anti Anxiety Agent,Anti Anxiety Agents,Anti Anxiety Drug,Anti Anxiety Drugs,Anti Anxiety Effect,Anti Anxiety Effects,Drug, Anti-Anxiety,Drugs, Anti-Anxiety,Effect, Anti-Anxiety,Effect, Antianxiety,Effect, Anxiolytic,Effects, Anti-Anxiety,Effects, Antianxiety,Effects, Anxiolytic,Minor Tranquilizing Agents,Minor Tranquillizing Agents
D015640	Ion Channel Gating	The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.	Gating, Ion Channel,Gatings, Ion Channel,Ion Channel Gatings