Solitary horizontal cells in culture--II. A new tool for examining effects of photoreceptor neurotransmitter candidates.
Membrane potentials of solitary horizontal cells dissociated from goldfish retinas were intracellularly measured while applying various acidic amino acids. L-glutamate and kainic acid depolarized solitary horizontal cells at micromolar doses. Neither L- nor D-aspartate produced any change in solitary horizontal cell resting potentials. Low-amplitude responses to L-glutamate showed no sign of desensitization. A steady, plateau-like, dose-dependent component of solitary horizontal cell responses to either L-glutamate or kainic acid, though obscured during its rising phase by action potentials, was always recorded during maintained agonist applications. Responses to either L-glutamate or kainic acid reversed in polarity at membrane potentials between 0 and -20 mV. Responses to L-glutamate collapsed reversibly when extracellular sodium ions were replaced by choline ions. Responses to either L-glutamate or kainic acid were antagonized by relatively high doses of D-aspartate. These results demonstrate that retinal horizontal cell chemosensitivity to acidic amino acids persists after dissociation, and in several respects resembles that found in several other preparations, including retinas in situ.
D015074:2-Aminoadipic Acid / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005971:Glutamates / Q000494:pharmacology*; D006054:Goldfish; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D012160:Retina / Q000166:cytology*
D005971:Glutamates; D015074:2-Aminoadipic Acid; D001224:Aspartic Acid; D007608:Kainic Acid