Abstract:
:Mechanisms that mediate the calcium influx in mammalian horizontal cells were studied. Horizontal cells (HCs) enzymatically dissociated from the rabbit retina were recorded by the whole-cell configuration of the patch-clamp technique and by calcium image ratioespectrophotometry of Fura-2 loaded cells. AMPA-preferring glutamate receptors were shown to permeate Ca2+ in mammalian HCs by ionic substitution experiments. Furthermore, after blocking the L-type calcium current with nifedipine (100 microM), calcium current through the AMPA-preferring glutamate receptors was measured. Calcium image ratioespectrophotometry was performed on the dissociated HCs in order to determine the changes in the intracellular calcium ([Ca2+]i). Fura-2 microspectrophotometry showed that in HCs, K+-induced cell depolarization promoted an increase in [Ca2+]i, mediated by the L-type calcium channels, since it was abolished in the presence of nifedipine. The increase in [Ca2+], upon cell depolarization was observed throughout each cell: however, it was maximal at the cell soma. Activation of glutamate receptors in dissociated HCs by glutamate, AMPA or kainate promoted an increase in [Ca2+]i. This increase in [Ca2+]i, was abolished in nominally Ca2+-free solution (0 mM Ca2+); in contrast, nifedipine decreased the glutamate-induced influx of calcium in ca. 50%. The present study demonstrates that calcium may permeate through glutamate receptors expressed in HCs of the rabbit retina.
journal_name
Vis Neuroscijournal_title
Visual neuroscienceauthors
Rivera L,Blanco R,de la Villa Psubject
Has Abstractpub_date
2001-11-01 00:00:00pages
995-1002issue
6eissn
0952-5238issn
1469-8714pii
S0952523801186165journal_volume
18pub_type
杂志文章abstract::We have investigated the effects of inactivation of localized sites in area 17 on the visual responses of cells in visuotopically corresponding regions of area 18. Experiments were performed on adult normal cats. The striate cortex was inactivated by the injection of nanoliters of lidocaine hydrochloride or of gamma-a...
journal_title:Visual neuroscience
pub_type: 杂志文章
doi:10.1017/s0952523800001826
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journal_title:Visual neuroscience
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pub_type: 杂志文章,评审
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journal_title:Visual neuroscience
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pub_type: 杂志文章,评审
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journal_title:Visual neuroscience
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journal_title:Visual neuroscience
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