title: Effects of nitric oxide, light adaptation and APB on spectral characteristics of H1 horizontal cells in carp retina.
abstract: The spectral characteristics of cone-driven horizontal cells of H1 subtype (H1 HCs) receiving main synaptic input from red-sensitive cones were studied in light- and dark-adapted retinae of carp. The spectral sensitivity profile of H1 HCs in dark-adapted retinae was practically the same as the absorption spectrum of red-sensitive cones. Light-adaptation decreased the sensitivity preferentially in the short-wavelength (blue/green) region, resulting in a relative enhancement of the 617 nm peak. Application of nitric oxide (NO) donors, sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG or GSNO), or dopamine to dark-adapted retinae decreased the sensitivity preferentially in blue/green region, an effect similar to that of light-adaptation. Application of haemoglobin (Hb, an NO scavenger) or 2-amino-4-phosphonobutyrate (APB, a metabotropic glutamate receptor agonist), to light-adapted retinae increased the sensitivity preferentially in the blue/green region, an effect similar to dark-adaptation. The photoresponses of H1 HCs were univariant in dark-adapted retinae as well as Hb-treated light-adapted retinae. In light-adapted retinae with normal Ringer, however, the univariance did not hold. These results suggested that the photoresponses of H1 HCs to short-wavelength stimuli contain a depolarising (sign-reversing) component, which can be activated by light-adaptation or application of NO and dopamine, and inactivated by dark-adaptation or deprivation of NO or application of APB.
authors.affiliation: Supermolecular Division, Electrotechnical Laboratory, Tsukuba, Ibaraki, Japan. mayamada@etl.go.jp
authors.forename: M
authors.initials: M
authors.lastname: Yamada
authors.forename: S P
authors.initials: SP
authors.lastname: Fraser
authors.forename: T
authors.initials: T
authors.lastname: Furukawa
authors.forename: H
authors.initials: H
authors.lastname: Hirasawa
authors.forename: K
authors.initials: K
authors.lastname: Katano
authors.forename: M
authors.initials: M
authors.lastname: Djamgoz
authors.forename: S
authors.initials: S
authors.lastname: Yasui
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000613:Aminobutyrates / Q000494:pharmacology*; D000818:Animals; D002347:Carps / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D012160:Retina / Q000187:drug effects* / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology
chemical_list: D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D006454:Hemoglobins; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; C012729:2-amino-4-phosphonobutyric acid