Effects of electrical coupling on the cone-horizontal cell circuit in the catfish retina

1986 ◽  
Vol 53 (3) ◽  
pp. 173-187 ◽  
Author(s):  
Robert Siminoff
Keyword(s):  
Horizontal Cell ◽  
Electrical Coupling ◽  
Cell Circuit

Electrical coupling of retinal horizontal cells mediated by distinct voltage-independent junctions

1999 ◽  
Vol 16 (5) ◽  
pp. 811-818 ◽  
Author(s):  
CHENGBIAO LU ◽  
DAO-QI ZHANG ◽  
DOUGLAS G. McMAHON
Keyword(s):  
Single Channel ◽  
Lucifer Yellow ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
Cell Voltage ◽  
Horizontal Cells ◽  
Simultaneous Application ◽  
Dependent Inactivation ◽  
Cellular Junctions ◽  
Voltage Dependent

Electrical coupling between H2 horizontal cell pairs isolated from the hybrid bass retina was studied using dual whole-cell, voltage-clamp technique. Voltage-dependent inactivation of junctional currents in response to steps in transjunctional voltage (Vj) over a range of ±100 mV was characterized for 89 cell pairs. Approximately one-quarter of the pairs exhibited strongly voltage-dependent junctions (>50% reduction in junctional current at ±100 mV), another quarter of the pairs exhibited voltage-independent junctional current (<5% reduction at ±100 mV), and the remainder of the pairs exhibited intermediate values for voltage inactivation. We focused on further characterizing the Vj-independent junctions of horizontal cells, which have not been described previously in detail. When Lucifer Yellow dye was included in one recording pipette, pairs exhibiting Vj-independent coupling showed no (9/12), or limited (3/12), passage of dye. Vj-independent coupling was markedly less sensitive to the modulators SNP (100–300 μM, −9% reduction in coupling) and dopamine (100–300 μM, −6%) than were Vj-dependent junctions (−45% and −44%). However, simultaneous application of both SNP and dopamine significantly reduced Vj-independent coupling (−56%). Both Vj-independent and Vj-dependent junctions were blocked by DMSO (1–2%), but Vj-independent junctions were not blocked by heptanol. Single-channel junctional conductances of Vj-independent junctions range from 112–180 pS, versus 50–60 pS for Vj-dependent junctions. The results reveal that Vj-independent coupling in a subpopulation of horizontal cells from the hybrid bass retina is mediated by cellular junctions with physiological and pharmacological characteristics distinct from those previously described in fish horizontal cells.

A comparison of receptive field and tracer coupling size of horizontal cells in the rabbit retina

1995 ◽  
Vol 12 (5) ◽  
pp. 985-999 ◽  
Author(s):  
Stewart A. Bloomfield ◽  
Daiyan Xin ◽  
Seth E. Persky
Keyword(s):  
Receptive Field ◽  
Gap Junctions ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
Receptive Fields ◽  
Electrical Current ◽  
Horizontal Cells ◽  
Field Size ◽  
Narrow Slit ◽  
Retinal Neuron

AbstractThe large receptive fields of retinal horizontal cells are thought to reflect extensive electrical coupling via gap junctions. It was shown recently that the biotinylated tracers, biocytin and Neurobiotin, provide remarkable images of coupling between many types of retinal neuron, including horizontal cells. Further, these demonstrations of tracer coupling between horizontal cells rivaled the size of their receptive fields, suggesting that the pattern of tracer coupling may provide some index of the extent of electrical coupling. We studied this question by comparing the receptive field and tracer coupling size of dark-adapted horizontal cells recorded in the superfused, isolated retina-eyecup of the rabbit. Both the edge-to-edge receptive field and space constants (λ) were computed for each cell using a long, narrow slit of light displaced across the retinal surface. Cells were subsequently labeled by iontophoretic injection of Neurobiotin. The axonless A-type horizontal cells showed extensive, homologous tracer coupling in groups greater than 1000 covering distances averaging about 2 mm. The axon-bearing B-type horizontal cells were less extensively tracer coupled, showing homologous coupling of the somatic endings in groups of about 100 cells spanning approximately 400 μm and a separate homologous coupling of the axon terminal endings covering only about 275 μm. Moreover, we observed a remarkable, linear relationship between the size of the receptive fields of each of the three horizontal cell endings and the magnitude of their tracer coupling. Our findings suggest that the extent of tracer coupling provides a strong, linear index of the magnitude of electrical current flow, as derived from receptive-field measures, across groups of coupled horizontal cells. These data thus provide the first direct evidence that the receptive-field size of horizontal cells is related to the extent of their coupling via gap junctions.

Involvement of D1 and D2 Dopamine Receptors in the Control of Horizontal Cell Electrical Coupling in the Turtle Retina

1989 ◽  
Vol 1 (3) ◽  
pp. 247-257 ◽  
Author(s):  
M. Piccolino ◽  
G. Demontis ◽  
P. Witkovsky ◽  
E. Strettoi ◽  
G. C. Cappagli ◽  
...  
Keyword(s):  
Dopamine Receptors ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
D2 Dopamine Receptors

Gap-junctional properties of electrically coupled skate horizontal cells in culture

1993 ◽  
Vol 10 (2) ◽  
pp. 287-295 ◽  
Author(s):  
Haohua Qian ◽  
Robert Paul Malchow ◽  
Harris Ripps
Keyword(s):  
Receptive Field ◽  
Lucifer Yellow ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
Cell Voltage ◽  
Horizontal Cells ◽  
Electrical Synapse ◽  
Cell Coupling ◽  
Junctional Conductance ◽  
Gap Junctional

AbstractWhole-cell voltage-clamp recordings were used to examine the unusual pharmacological properties of the electrical coupling between rod-driven horizontal cells in skate retina as revealed previously by receptive-field measurements (Qian & Ripps, 1992). The junctional resistance was measured in electrically coupled cell pairs that had been enzymatically isolated and maintained in culture; the typical value was about 19.92 MΩ(n = 45), more than an order of magnitude lower than the nonjunctional membrane resistance. These data and the intercellular spread of the fluorescent dye Lucifer Yellow provide a good indication that skate horizontal cells are well coupled. The junctional conductance between cells was not modulated by the neurotransmitters dopamine (200 μM) or GABA (1 mM), nor was it affected by the membrane-permeable analogues of cAMP or cGMP, or the adenylate cyclase activator, forskolin. Although resistant to agents that have been reported to alter horizontal-cell coupling in cone-driven horizontal cells, the junctional conductance between paired horizontal cells of skate was greatly reduced by the application of 20 mM acetate, which is known to effectively reduce intracellular pH. Together with the results obtained in situ on the receptive-field properties of skate horizontal cells, these findings indicate that the gap-junctional properties of rod-driven horizontal cells of the skate are fundamentally different from those of cone-driven horizontal cells in other species. This raises the possibility that there is more than one class of electrical synapse on vertebrate horizontal cells.

Endogenous Activation of Dopamine D2 Receptors Regulates Dopamine Release in the Fish Retina

1997 ◽  
Vol 78 (1) ◽  
pp. 439-449 ◽  
Author(s):  
Yu Wang ◽  
Krisztina Harsanyi ◽  
Stuart C. Mangel
Keyword(s):  
Dopamine Release ◽  
Divalent Cations ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
D2 Receptors ◽  
Horizontal Cells ◽  
Light Stimulation ◽  
Full Field ◽  
Dopamine D2 ◽  
Fish Retina

Wang, Yu, Krisztina Harsanyi, and Stuart C. Mangel. Endogenous activation of dopamine D2 receptors regulates dopamine release in the fish retina. J. Neurophysiol. 78: 439–449, 1997. In the fish retina, horizontal cell electrical coupling and light responsiveness is regulated by activation of dopamine D1 receptors that are located on the horizontal cells themselves. The effects of dopamine and dopamine D2 receptor agonists and antagonists on cone horizontal cell light responses were studied in in vitro superfused goldfish retinas. Horizontal cell light responses and electrical coupling were assessed by monitoring responses to full-field stimuli and to small, centered (0.4 mm diam) spots of light, respectively. Dopamine (0.2–10 μM) application uncoupled horizontal cells and decreased their responses to full-field stimuli. Application of the D2 antagonist eticlopride (10–50 μM) produced similar effects, whereas quinpirole (0.1–10 μM), a D2 agonist, had the opposite effects. The uncoupling effect of eticlopride was blocked by prior application of SCH23390 (10 μM), a D1 receptor antagonist, and was eliminated after destruction of dopaminergic neurons by prior treatment of the retinas with 6-hydroxydopamine. The effects of these D2 drugs were observed following flickering light stimulation, but were not observed following sustained light stimulation. Application of the D2 antagonists sulpiride (0.5–20 μM) and spiperone (0.25–10 μM) uncoupled horizontal cells when the total concentration of divalent cations (Mg2+ and Ca2+) in the Ringer solution was 1.1 mM. However, when the concentration of divalent cations was 0.2 mM, spiperone had no effect on the horizontal cells and sulpiride increased coupling. In contrast, eticlopride uncoupled the cells and decreased their light responsiveness irrespective of the concentration of divalent cations. The effects of quinpirole also depended on the concentration of divalent cations; its coupling effect was reduced when the divalent cation concentration was increased from 0.2 to 1.0 mM. The results suggest that activation of D2 receptors in the fish retina by endogenous dopamine decreases dopamine release and is greater after flickering compared with sustained light stimulation. These D2 receptors thus function as presynaptic autoreceptors that inhibit dopamine release from dopaminergic cells. In addition, the results also indicate that the effectiveness of some D2 drugs at these receptors is dependent on the concentration of divalent cations.

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