Differential Expression of High- and Two Types of Low-Voltage–Activated Calcium Currents in Rod and Cone Bipolar Cells of the Rat Retina

2000 ◽  
Vol 83 (1) ◽  
pp. 513-527 ◽  
Author(s):  
Zhuo-Hua Pan
Keyword(s):  
Low Voltage ◽  
Cell Voltage ◽  
Small Population ◽  
Bipolar Cells ◽  
Calcium Currents ◽  
Morphological Identification ◽  
Axon Terminals ◽  
High Concentrations ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

Whole cell voltage-clamp recordings were performed to investigate voltage-activated Ca2+ currents in acutely isolated retinal bipolar cells of rats. Two groups of morphologically different bipolar cells were observed. Bipolar cells of the first group, which represent the majority of isolated bipolar cells, were immunoreactive to protein kinase C (PKC) and, therefore likely to be rod bipolar cells. Bipolar cells of the second group, which represent only a small population of isolated bipolar cells, did not show PKC immunoreactivity and were likely to be cone bipolar cells. The validity of morphological identification of bipolar cells was further confirmed by the presence of GABAC responses in these cells. Bipolar cells of both groups displayed low-voltage–activated (LVA) Ca2+ currents with similar voltage dependence of activation and steady-state inactivation. However, the activation, inactivation, and deactivation kinetics of the LVA Ca2+ currents between rod and cone bipolar cells differed. Particularly, the LVA Ca2+ currents of rod bipolar cells displayed both transient and sustained components. In contrast, the LVA Ca2+ currents of cone bipolar cells were mainly transient. In addition, the LVA Ca2+ channels of rod bipolar cells were more permeable to Ba2+ than to Ca2+, whereas those of cone bipolar cells were equally or less permeable to Ba2+ than to Ca2+. The LVA Ca2+ currents of both rod and cone bipolar cells were antagonized by high concentrations of nimodipine with IC50of 17 and 23 μM, respectively, but largely resistant to Cd2+ and Ni2+. Bipolar cells of both groups also displayed high-voltage–activated (HVA) Ca2+ currents. The HVA Ca2+ currents were, at least in part, to be L-type that were potentiated by BayK-8644 (1 μM) and largely antagonized by low concentrations of nimodipine (5 μM). The L-type Ca2+channels were almost exclusively located at the axon terminals of rod bipolar cells but expressed at least in the cell soma of cone bipolar cells. Results of this study indicate that rod and cone bipolar cells of the mammalian retina differentially express at least two types of LVA Ca2+ channels. Rod and cone bipolar cells also show different spatial distribution of L-type Ca2+channels.

Morphological differentiation of bipolar cells in the ferret retina

1999 ◽  
Vol 16 (6) ◽  
pp. 1133-1144 ◽  
Author(s):  
E.D. MILLER ◽  
M.N. TRAN ◽  
G.-K. WONG ◽  
D.M. OAKLEY ◽  
R.O.L. WONG
Keyword(s):  
Visual Processing ◽  
Plexiform Layer ◽  
Morphological Differentiation ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Axon Terminals ◽  
Ribbon Synapses ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells ◽  
Dye Labeling

Bipolar cells are not only important for visual processing but input from these cells may underlie the reorganization of ganglion cell dendrites in the inner plexiform layer (IPL) during development. Because little is known about the development of bipolar cells, here we have used immunocytochemical markers and dye labeling to identify and follow their differentiation in the neonatal ferret retina. Putative cone bipolar cells were immunoreacted for calbindin and recoverin, and rod bipolar cells were immunostained for protein kinase C (PKC). Our results show that calbindin-immunoreactive cone bipolar cells appear at postnatal day 15 (P15), at which time their axonal terminals are already localized to the inner half of the IPL. By contrast, recoverin-immunoreactive cells with terminals in the IPL are present at birth, but many of these cells may be immature photoreceptors. By the second postnatal week, recoverin-positive cells resembling cone bipolar cells were clearly present, and with increasing age, two distinct strata of immunolabeled processes occupied the IPL. PKC-containing rod bipolar cells emerged by the fourth postnatal week and at this age have stratified arbors in the inner IPL. The early bias of bipolar axonal arbors in terminating in the inner or outer half of the IPL is confirmed by dye labeling of cells with somata in the inner nuclear layer. At P10, several days before ribbon synapses have been previously observed in the ferret IPL, the axon terminals of all dye-labeled bipolar cells were clearly stratified. The results suggest that bipolar cells could provide spatially localized interactions that are suitable for guiding dendritic lamination in the inner retina.

Unique functional properties of the APB sensitive and insensitive rod pathways signaling light decrements in mouse retinal ganglion cells

2006 ◽  
Vol 23 (1) ◽  
pp. 127-135 ◽  
Author(s):  
GUO-YONG WANG
Keyword(s):  
Functional Properties ◽  
Ganglion Cells ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Mouse Retina ◽  
Clear Cut ◽  
Types Of Information ◽  
Rod Bipolar Cells ◽  
Rod Pathway ◽  
Cone Bipolar Cells

Light decrements are mediated by two distinct groups of rod pathways in the dark-adapted retina that can be differentiated on the basis of their sensitivity to the glutamate agonist DL-2-amino-phosphonobutyric (APB). By means of the APB sensitive pathway, rods transmit light decrementsviarod bipolar cells to AII amacrine cells, then to Off cone bipolar cells, which in turn innervate the dendrites of Off ganglion cells. APB hyperpolarizes rod bipolar cells, thus blocking this rod pathway. With APB insensitive pathways, rods either directly synapse onto Off cone bipolar cells, or rods pass light decrement signal to cones by gap junctions. In the present study, whole-cell patch-clamp recordings were made from ganglion cells in the dark-adapted mouse retina to investigate the functional properties of APB sensitive and insensitive rod pathways. The results revealed several clear-cut differences between the APB sensitive and APB insensitive rod pathways. The latency of Off responses to a flashing spot of light was significantly shorter for the APB insensitive pathways than those for the APB sensitive pathway. Moreover, Off responses of the APB insensitive pathways were found to be capable of following substantially higher stimulus frequencies. Nitric oxide was found to selectively block Off responses in the APB sensitive rod pathway. Collectively, these results provide evidence that the APB sensitive and insensitive rod pathways can convey different types of information signaling light decrements in the dark-adapted retina.

Spontaneous regenerative activity in mammalian retinal bipolar cells: Roles of multiple subtypes of voltage-dependent Ca2+ channels

2003 ◽  
Vol 20 (2) ◽  
pp. 131-139 ◽  
Author(s):  
YU-PING MA ◽  
ZHUO-HUA PAN
Keyword(s):  
Spontaneous Activity ◽  
Bipolar Cells ◽  
Potential Oscillations ◽  
Regenerative Activity ◽  
Voltage Dependent ◽  
Cell Groups ◽  
Retinal Bipolar Cells ◽  
Ca2 Channels ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

Patch-clamp recordings were used to investigate the properties of the regenerative activity in acutely isolated bipolar cells from the rat retina. Spontaneous, pacemaker-like membrane potential oscillations were observed in all rod bipolar cells and the majority of cone bipolar cells. The waveform of the regenerative potential was stereotypical but distinct among different bipolar cell groups, especially between rod and cone bipolar cells. The spontaneous activity was completely blocked by Co2+, suggesting that Ca2+ influx through voltage-dependent Ca2+ channels was required for initiating such activity. Ca2+-induced Ca2+ release, however, was not found to be involved. The spontaneous activity was also blocked by mibefradil, a T-type Ca2+ channel antagonist. In contrast, application of nimodipine, an L-type Ca2+ current antagonist, affected mainly the waveform of the regenerative potential. This study shows that mammalian retinal bipolar cells in isolation are also capable of generating Ca2+-dependent spontaneous regenerative potential. However, T-type Ca2+ channels appear to be essential for the initiation of the spontaneous activity in mammalian bipolar cells.

scholarly journals Different Contributions of GABAA and GABAC Receptors to Rod and Cone Bipolar Cells in a Rat Retinal Slice Preparation

1998 ◽  
Vol 79 (3) ◽  
pp. 1384-1395 ◽  
Author(s):  
Thomas Euler ◽  
Heinz Wässle
Keyword(s):  
Receptor Antagonist ◽  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Phosphinic Acid ◽  
Bipolar Cells ◽  
Resting Potential ◽  
Slice Preparation ◽  
Metabotropic Glutamate ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

Euler, Thomas and Heinz Wässle. Different contributions ofGABAA and GABAC receptors to rod and cone bipolar cells in a rat retinal slice preparation. J. Neurophysiol. 79: 1384–1395, 1998. Whole cell currents were recorded from rod and cone bipolar cells in a slice preparation of the rat retina. Use of the gramicidin D perforated-patch technique prevented loss of intracellular compounds. The recorded cells were identified morphologically by injection with Lucifer yellow. During the recordings, the cells were isolated synaptically by extracellular cobalt. To distinguish the γ-aminobutyric acid (GABA) receptors pharmacologically, theGABAA receptor antagonist, bicuculline, and the GABAC receptor antagonist, 3-aminopropyl(methyl)phosphinic acid, were used. In all bipolar cells tested, application of GABA induced postsynaptic chloride currents that hyperpolarized the cells from their resting potential of about −40 mV. GABA was applied at different concentrations to allow for the different affinity of GABA at GABAA and GABAC receptors. At a GABA concentration of 25 μM, in the case of rod bipolar cells, ∼70% of the current was found to be mediated by GABAC receptors. In the case of cone bipolar cells, only ∼20% of the current was mediated by GABAC receptors. Furthermore, this GABAC-mediated fraction varied among the different morphological types of cone bipolar cells, supporting the hypothesis of distinct functional roles for the different types of cone bipolar cells. There is evidence that the efficacy of GABAC receptors is modulated by glutamate through metabotropic glutamate receptors. We tested this hypothesis by applying agonists of metabotropic glutamate receptors (mGluR)1/5 to rod bipolar cells. The specific agonist (±)-trans-azetidine-2,4-dicarboxylic acid and the potent mGluR agonist quisqualic acid reduced the amplitude of the GABAC responses by 10–30%. This suggests a functional role for the modulation of GABAC receptors by the metabotropic glutamate receptors mGluR1/5.

Modulation of high- and low-voltage-activated calcium currents in smooth muscle by calcium

1997 ◽  
Vol 273 (3) ◽  
pp. C883-C892 ◽  
Author(s):  
J. G. McCarron ◽  
J. G. McGeown ◽  
J. V. Walsh ◽  
F. S. Fay
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Cell Voltage ◽  
Calcium Currents ◽  
Dependent Protein Kinase ◽  
Maximal Increase ◽  
Current Test ◽  
Dependent Protein ◽  
Early Inhibition ◽  
Gastric Myocytes

Ca2+ currents (ICa) and cytoplasmic Ca2+ concentration ([Ca2+]c) were measured in isolated gastric myocytes from Bufo marinus using whole cell voltage clamp and fura 2, respectively. After a conditioning train of depolarizing pulses, high-voltage-activated ICa (test potential of +10 mV) was increased, returning to control values after approximately 85 s. This enhancement was [Ca2+]c dependent, with a maximal increase at approximately 600 nM [Ca2+]c. During the conditioning train, ICa measured at 70 ms, which provides a measure of high-voltage-activated current, initially decreased with each successive pulse to a minimum of 56 +/- 5% of the first pulse in the train. Thereafter, the 70-ms current showed considerable recovery. Blockade of calmodulin activity with a peptide (RS20) or calmidazolium did not affect the early inhibition but did abolish current recovery. A peptide inhibitor of calmodulin-dependent protein kinase II (CK3AA) had similar effects. Substraction of currents measured in the presence and absence of RS20 revealed a 2-s delay between the start of the train and the onset of current enhancement. It was also observed that low-voltage-activated current (test potential of -17 mV) was reduced to 76 +/- 7% of control 5 s after the conditioning train; this inhibition recovered to 92 +/- 4% after 35 s and was not dependent on [Ca2+]c elevation.

Distribution of protein kinase C isoforms in the cat retina

2002 ◽  
Vol 19 (5) ◽  
pp. 549-562 ◽  
Author(s):  
BOZENA FYK-KOLODZIEJ ◽  
WENHUI CAI ◽  
ROBERTA G. POURCHO
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Ganglion Cells ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Kinase C ◽  
Cat Retina ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

Immunocytochemical localization was carried out for five isoforms of protein kinase C (PKC) in the cat retina. In common with other mammalian species, PKCα was found in rod bipolar cells. Staining was also seen in a small population of cone bipolar cells with axon terminals ramifying near the middle of the inner plexiform layer (IPL). PKCβI was localized to rod bipolar cells, one class of cone bipolar cell, and numerous amacrine and displaced amacrine cells. Staining for PKCβII was seen in three types of cone bipolar cells as well as in amacrine and ganglion cells. Immunoreactivity for both PKCε and PKCζ was found in rod bipolar cells; PKCε was also seen in a population of cone bipolar cells and a few amacrine and ganglion cells whereas PKCζ was found in all ganglion cells. Double-label immunofluorescence studies showed that dendrites of the two PKCβII-positive OFF-cone bipolar cells exhibit immmunoreactivity for the kainate-selective glutamate receptor GluR5. The third PKCβII cone bipolar is an ON-type cell and did not stain for GluR5. The retinal distribution of these isoforms of PKC is consistent with a role in modulation of various aspects of neurotransmission including synaptic vesicle release and regulation of receptor molecules.

Light-Evoked Responses of Bipolar Cells in a Mammalian Retina

2000 ◽  
Vol 83 (4) ◽  
pp. 1817-1829 ◽  
Author(s):  
Thomas Euler ◽  
Richard H. Masland
Keyword(s):  
Gaba Receptor ◽  
Dynamic Range ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Chloride Current ◽  
Evoked Responses ◽  
Temporal Properties ◽  
Cation Current ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

We recorded light-evoked responses from rod and cone bipolar cells using patch-clamp techniques in a slice preparation of the rat retina. Rod bipolar cells responded to light with a sustained depolarization (on response) followed at light offset by a slight hyperpolarization. on and off cone bipolar cells were encountered, both with diverse temporal properties. The responses of rod bipolar cells were composed primarily of two components, a nonspecific cation current and a chloride current. The chloride current was reduced greatly in axotomized cells and could be suppressed by coapplication of the GABAA antagonist bicuculline and the GABAC antagonist (1,2,5,6-tetrahydropyridine-4-yl)methylphosphinic acid. This suggests that it largely reflects feedback from GABAergic amacrine cells. The response latency of intact rod bipolar cells was shorter than that of the axotomized cells, and the sensitivity curve covered more than twice the dynamic range. Application of the GABA receptor antagonists partially mimicked the effects of axotomy. These findings suggest that functional properties of the axon terminal system—notably synaptic feedback from amacrine cells—play an important role in defining the response properties of mammalian bipolar cells.

GABA- and glycine-activated currents in the rod bipolar cell of the rabbit retina

1995 ◽  
Vol 74 (2) ◽  
pp. 856-875 ◽  
Author(s):  
M. A. Gillette ◽  
R. F. Dacheux
Keyword(s):  
Gabaa Receptor ◽  
Bipolar Cell ◽  
Reversal Potential ◽  
Outward Current ◽  
Bipolar Cells ◽  
Morphological Identification ◽  
Response Curves ◽  
Patch Clamp Technique ◽  
T Distribution ◽  
Rod Bipolar Cells

1. Voltage- and ligand-gated currents were recorded from solitary rabbit rod bipolar cells using the whole cell patch-clamp technique. The rod bipolar cell forms a single, stereotypical physiological and morphological class of cells that was easily identified from other neurons and support cells after enzymatic and mechanical dissociation from isolated retina. Protein kinase C immunoreactivity confirmed the validity of using a purely morphological identification of this cell type. 2. Voltage steps in 15-mV increments from a holding potential of -45 mV elicited a large outward current activated near -30 mV. These voltage-gated currents were eliminated by using equimolar substitutions of Cs+ and tetraethylammonium+ for K+ in the pipette, indicating that they represent a mixture of K+ currents. 3. The putative inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and glycine activated inward Cl- currents when pressure-applied from pipettes placed near the axon terminals of rod bipolar cells, which were voltage-clamped at -45 mV. With changes in intracellular or extracellular Cl- concentration, the reversal potential of these ligand-gated currents changed as predicted by the Nernst equation for Cl- activity. The dose-response curves for GABA and glycine were sigmoidal with saturating concentrations of 100 and 300 microM, respectively. 4. GABA-activated currents were 1) reversibly reduced by the allosteric inhibitor picrotoxin and the competitive antagonist bicuculline; 2) potentiated by the benzodiazepine diazepam and the barbiturate barbital sodium; and 3) indistinguishable from muscimol-activated currents. There was no response to the GABAB agonist baclofen. Collectively, these data strongly suggest that the GABA-activated currents in rabbit rod bipolar cells are mediated by the GABAA receptor. This is similar to the GABA-activated currents in other mammalian rod bipolar cells. 5. Application of the conformationally restricted GABA analogue cis-4-aminocrotonic acid (CACA) failed to elicit a response, whereas the conformationally extended GABA analogue trans-4-aminocrotonic acid (TACA) elicited a response similar to that of GABA. Although bicuculline appeared to suppress the GABA-activated current slightly more than the TACA-activated current (not significant using Student's t-distribution), GABA- and TACA-activated currents were equally suppressed by picrotoxin and equally enhanced by diazepam and barbital sodium. These data, coupled with the inefficacy of CACA, argue against the existence of a GABAC-type channel in the rod bipolar cell of the rabbit and suggest that GABA and TACA were activating the same GABAA receptor-channel complex.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Development of Presynaptic Inhibition Onto Retinal Bipolar Cell Axon Terminals Is Subclass-Specific

2008 ◽  
Vol 100 (1) ◽  
pp. 304-316 ◽  
Author(s):  
Timm Schubert ◽  
Daniel Kerschensteiner ◽  
Erika D. Eggers ◽  
Thomas Misgeld ◽  
Martin Kerschensteiner ◽  
...  
Keyword(s):  
Bipolar Cell ◽  
Presynaptic Inhibition ◽  
Synapse Formation ◽  
Critical Role ◽  
Bipolar Cells ◽  
Inhibitory Synapses ◽  
Axon Terminals ◽  
Cell Recording ◽  
Retinal Bipolar Cells ◽  
Cone Bipolar Cells

Synaptic integration is modulated by inhibition onto the dendrites of postsynaptic cells. However, presynaptic inhibition at axonal terminals also plays a critical role in the regulation of neurotransmission. In contrast to the development of inhibitory synapses onto dendrites, GABAergic/glycinergic synaptogenesis onto axon terminals has not been widely studied. Because retinal bipolar cells receive subclass-specific patterns of GABAergic and glycinergic presynaptic inhibition, they are a good model for studying the development of inhibition at axon terminals. Here, using whole cell recording methods and transgenic mice in which subclasses of retinal bipolar cells are labeled, we determined the temporal sequence and patterning of functional GABAergic and glycinergic input onto the major subclasses of bipolar cells. We found that the maturation of GABAergic and glycinergic synapses onto the axons of rod bipolar cells (RBCs), on-cone bipolar cells (on-CBCs) and off-cone bipolar cells (off-CBCs) were temporally distinct: spontaneous chloride-mediated currents are present in RBCs earlier in development compared with on- and off-CBC, and RBCs receive GABAergic and glycinergic input simultaneously, whereas in off-CBCs, glycinergic transmission emerges before GABAergic transmission. Because on-CBCs show little inhibitory activity, GABAergic and glycinergic events could not be pharmacologically distinguished for these bipolar cells. The balance of GABAergic and glycinergic input that is unique to RBCs and off-CBCs is established shortly after the onset of synapse formation and precedes visual experience. Our data suggest that presynaptic modulation of glutamate transmission from bipolar cells matures rapidly and is differentially coordinated for GABAergic and glycinergic synapses onto distinct bipolar cell subclasses.

scholarly journals Two types of cone bipolar cells express voltage-gated Na+ channels in the rat retina

2008 ◽  
Vol 25 (5-6) ◽  
pp. 635-645 ◽  
Author(s):  
JINJUAN CUI ◽  
ZHUO-HUA PAN
Keyword(s):  
Plexiform Layer ◽  
Distinct Type ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Voltage Gated ◽  
Axon Terminals ◽  
Cation Current ◽  
Type 3 ◽  
Retinal Cone ◽  
Cone Bipolar Cells

AbstractTwo groups of retinal cone bipolar cells (CBCs) in rats were found to express voltage-gated Na+ channels. The axon terminals of the first group stratify in sublamina 2 of the inner plexiform layer (IPL) and partially overlap with the OFF-cholinergic band. This group was identified as type 3 CBCs. The axon terminals of the second group stratify in sublamina 3 of the IPL, slightly distal to the ON-cholinergic band. Cells of this second group resemble type 5 CBCs. In addition, we observed another group of ON-type CBCs with terminal stratification similar to that of the second group. However, this latter group did not show any Na+ current, instead exhibiting a large hyperpolarization-activated cyclic nucleotide-gated cation current, suggesting the existence of two subclasses of physiologically distinct type 5 CBCs. Both groups of Na+-expressing bipolar cells were capable of generating a rapid tetrodotoxin-sensitive action potential as revealed by current injection. Multiple spike-like potentials were also observed in some of these cells. Results of this study provide valuable insights into the function of voltage-gated Na+ channels of retinal bipolar cells in retinal processing.

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