Differential expression of voltage-activated calcium currents in zebrafish retinal ganglion cells

2006 ◽  
Vol 84 (3) ◽  
pp. 497-504 ◽  
Author(s):  
Luoxiu Huang ◽  
Lei Li
Keyword(s):  
Differential Expression ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Calcium Currents ◽  
Retinal Ganglion

scholarly journals Two Metabotropic γ-Aminobutyric Acid Receptors Differentially Modulate Calcium Currents in Retinal Ganglion Cells

1997 ◽  
Vol 110 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Jian Zhang ◽  
Wen Shen ◽  
Malcolm M. Slaughter
Keyword(s):  
Retinal Ganglion Cells ◽  
Gaba Receptors ◽  
Gaba Receptor ◽  
Ganglion Cells ◽  
Calcium Currents ◽  
Gabab Receptors ◽  
Aminobutyric Acid ◽  
Retinal Ganglion ◽  
Wide Range ◽  
Prepulse Facilitation

Metabotropic γ-aminobutyric acid (GABA) receptors were studied in amphibian retinal ganglion cells using whole cell current and voltage clamp techniques. The aim was to identify the types of receptor present and their mechanisms of action and modulation. Previous results indicated that ganglion cells possess two ionotropic GABA receptors: GABAAR and GABACR. This study demonstrates that they also possess two types of metabotropic GABAB receptor: one sensitive to baclofen and another to cis-aminocrotonic acid (CACA). The effects of these selective agonists were blocked by GDP-β-S. Baclofen suppressed an ω-conotoxin–GVIA-sensitive barium current, and this action was reversed by prepulse facilitation, indicative of a direct G-protein pathway. The effect of baclofen was also partially occluded by agents that influence the protein kinase A (PKA) pathway. But the effect of PKA activation was unaffected by prepulse facilitation, indicating PKA acted through a parallel pathway. Calmodulin antagonists reduced the action of baclofen, whereas inhibitors of calmodulin phosphatase enhanced it. Antagonists of internal calcium release, such as heparin and ruthenium red, did not affect the baclofen response. Thus, the baclofen-sensitive receptor may respond to influx of calcium. The CACA-sensitive GABA receptor reduced current through dihydropyridine-sensitive channels. Sodium nitroprusside and 8-bromo-cGMP enhanced the action of CACA, indicating that a nitric oxide system can up-regulate this receptor pathway. CACA-sensitive and baclofen-sensitive GABAB receptors reduced spike activity in ganglion cells. Overall, retinal ganglion cells possess four types of GABA receptor, two ionotropic and two metabotropic. Each has a unique electrogenic profile, providing a wide range of neural integration at the final stage of retinal information processing.

Differential expression of sodium channel genes in retinal ganglion cells

1997 ◽  
Vol 50 (1-2) ◽  
pp. 197-204 ◽  
Author(s):  
J. Fjell ◽  
S. Dib-Hajj ◽  
K. Fried ◽  
J.A. Black ◽  
S.G. Waxman
Keyword(s):  
Sodium Channel ◽  
Differential Expression ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion

Calcium currents in turtle retinal ganglion cells. II. Dopamine modulation via a cyclic AMP-dependent mechanism

1994 ◽  
Vol 71 (2) ◽  
pp. 743-752 ◽  
Author(s):  
Y. Liu ◽  
E. M. Lasater
Keyword(s):  
Cyclic Amp ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Specific Inhibitor ◽  
D1 Receptor ◽  
Calcium Currents ◽  
Direct Result ◽  
Retinal Ganglion ◽  
Isolated Cells ◽  
Voltage Dependent

1. Voltage-activated calcium currents participate in shaping the firing pattern of neurons. Calcium currents also have a role in signal transduction. In the retina, little is known of the regulation of calcium entry into neurons via voltage-activated channels. In the present series of experiments we used standard whole cell and perforated patch clamp techniques to study the ability of the neurotransmitter dopamine (DA) to modulate voltage-dependent calcium currents in isolated turtle retinal ganglion cells. 2. Two types of calcium current have been described in these cells, one transient and the other sustained. Here we focused our studies primarily on the sustained current (ICa). Exogenous DA reduced ICa in some cells (59%), facilitated ICa in others (17%), or had no effect on the remainder (24%). Regardless of the action of DA, there was no effect on the voltage dependence of ICa. In addition, the effects were all reversible. The average magnitude of decrease was 43%, whereas that of increase was 75%. 3. The application of a specific D1 receptor agonist, SKF38393, mimicked the effect of DA. This was also true for a membrane permeable cyclic AMP (cAMP) analogue (8-CPT-cAMP). Inhibition of protein kinase A (PKA) activity by a specific inhibitor, IP20-amide, injected into cells prevented the modulatory effects of DA on ICa. 4. Immunocytochemical studies demonstrated that DA stimulation of the retina significantly increased the level of cAMP immunoreactivity in peripheral ganglion cells, whereas those cells in central retina were less affected. Forskolin induced a general elevation of cytoplasmic cAMP staining in all ganglion cells. 5. Current clamp experiments were carried out to determine the role of the calcium currents in action potential generation. Both the sustained and transient currents participated in the shaping of current-induced firing patterns of isolated cells. Depolarizing current-induced spiking of ganglion cells was found to be highly modified by dopamine. 6. These results support the notion that endogenous DA modulates the conductance of voltage-dependent calcium channels in turtle retinal ganglion cells and that this modulation is mediated by a D1 dopamine receptor-cAMP-PKA pathway. The direct result of this modulation is an alteration in the signaling properties of certain cells.

Two-fold effect of Angiotensin II on voltage-dependent calcium currents in rat retinal ganglion cells

1996 ◽  
Vol 718 (1-2) ◽  
pp. 112-116 ◽  
Author(s):  
Elke Guenther ◽  
Susanne Schmid ◽  
Birgit Hewig ◽  
Konrad Kohler
Keyword(s):  
Angiotensin Ii ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Calcium Currents ◽  
Retinal Ganglion ◽  
Voltage Dependent
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