Differential Contribution of Gap Junctions to the Membrane Properties of ON- and OFF-Bipolar Cells of the Rat Retina

Gap junctions are ubiquitous within the retina, but in general, it remains to be determined whether gap junction coupling between specific cell types is sufficiently strong to mediate functionally relevant coupling via electrical synapses. From ultrastructural, tracer coupling and immunolabeling stu...

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Bibliographic Details
Published in:Cellular and molecular neurobiology 2021-03, Vol.41 (2), p.229-245
Main Authors: Fournel, Rémi, Hartveit, Espen, Veruki, Margaret Lin
Format: Article
Language:English
Subjects:
Amacrine cells
Biomedical and Life Sciences
Biomedicine
Bipolar cells
Cell Biology
Conductance
Frogs
Gap junctions
Neurobiology
Neurosciences
Original Research
Retina
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Summary:Gap junctions are ubiquitous within the retina, but in general, it remains to be determined whether gap junction coupling between specific cell types is sufficiently strong to mediate functionally relevant coupling via electrical synapses. From ultrastructural, tracer coupling and immunolabeling studies, there is clear evidence for gap junctions between cone bipolar cells, but it is not known if these gap junctions function as electrical synapses. Here, using whole-cell voltage-clamp recording in rat (male and female) retinal slices, we investigated whether the gap junctions of bipolar cells make a measurable contribution to the membrane properties of these cells. We measured the input resistance ( R N ) of bipolar cells before and after applying meclofenamic acid (MFA) to block gap junctions. In the presence of MFA, R N of ON-cone bipolar cells displayed a clear increase, paralleled by block of the electrical coupling between these cells and AII amacrine cells in recordings of coupled cell pairs. For OFF-cone and rod bipolar cells, R N did not increase in the presence of MFA. The results for rod bipolar cells are consistent with the lack of gap junctions in these cells. However, for OFF-cone bipolar cells, our results suggest that the morphologically identified gap junctions between these cells do not support a junctional conductance that is sufficient to mediate effective electrical coupling. Instead, these junctions might play a role in chemical and/or metabolic coupling between subcellular compartments.
ISSN:0272-4340
1573-6830
DOI:10.1007/s10571-020-00845-y