title: Two types of cone bipolar cells express voltage-gated Na+ channels in the rat retina.
abstract: Two 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.
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: Jinjuan
authors.initials: J
authors.lastname: Cui
authors.forename: Zhuo-Hua
authors.initials: ZH
authors.lastname: Pan
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D003627:Data Interpretation, Statistical; D004594:Electrophysiology; D007150:Immunohistochemistry; D018408:Patch-Clamp Techniques; D051381:Rats; D020318:Rats, Long-Evans; D051245:Retinal Bipolar Cells / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000096:biosynthesis / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013779:Tetrodotoxin