Ca2+-permeable and Ca2+-impermeable AMPA receptors coexist on horizontal cells.
Fura-2 fluorescent calcium imaging was used for analyzing the subtype of AMPA receptors in freshly dissociated horizontal cells of carp retina. Exogenous application of AMPA induced an increase of intracellular concentration of free Ca2+ ([Ca2+]i) in horizontal cells, while the [Ca2+]i increase was partly inhibited by nifedipine. The residual [Ca2+]i increase was completely eliminated by joro spider toxin-3, a blocker of Ca2+-permeable AMPA receptors. On the other hand, the application of pentobarbital, which blocked Ca2+-impermeable AMPA receptors, could also partly inhibit the increase of [Ca2+]i, implying that the application of AMPA induced the activation of both Ca2+-permeable and Ca2+-impermeable AMPA receptors and the consequent activation of voltage-gated Ca2+ channels. Taken together, these results suggested that Ca2+-permeable and Ca2+-impermeable AMPA receptors were coexpressed on horizontal cells.
Huang
Shi-Yong
SY
Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai, China.
Liang
Pei-Ji
PJ
D000759:Adjuvants, Anesthesia / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002347:Carps; D002478:Cells, Cultured; D004347:Drug Interactions; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D010424:Pentobarbital / Q000494:pharmacology; D018091:Receptors, AMPA / Q000378:metabolism*; D012160:Retina / Q000166:cytology*; D013111:Spider Venoms / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D000759:Adjuvants, Anesthesia; D002121:Calcium Channel Blockers; D018690:Excitatory Amino Acid Agonists; C044936:JSTX spider toxin; D018091:Receptors, AMPA; D013111:Spider Venoms; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D010424:Pentobarbital; D009543:Nifedipine; D002118:Calcium