Carp horizontal cells in culture respond selectively to L-glutamate and its agonists.
Horizontal cells were enzymatically isolated from the carp retina and maintained in culture for 2-7 days. Cultured horizontal cells typically had resting membrane potentials of -50 to -70 mV and input resistances of 100-150 m omega. The cells were treated with a number of neurotransmitter agents and their analogues. Significant responses were evoked only by 3,4-dihydroxyphenylalanine (dopamine), L-glutamate, and certain glutamate analogues. The responses to dopamine were inconsistent; most often, the membrane hyperpolarized and input resistances increased. However, highly characteristic responses to L-glutamate and its analogues, quisqualate and kainate, were observed in virtually all of the cells tested. The responses consisted of an initial graded depolarization accompanied by a resistance increase, followed in most cases by a prolonged (1- to 2-min) regenerative depolarization. The regenerative component of the response appears to be Ca2+ dependent, while the underlying graded potential may be due to a decrease in K+ conductance of the membrane.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002347:Carps; D046508:Culture Techniques; D004298:Dopamine / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000187:drug effects; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000187:drug effects; D012160:Retina / Q000187:drug effects*
D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D011956:Receptors, Cell Surface; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D004298:Dopamine