Studies on the dopamine-dependent modulation of amino acid-gated currents in cone horizontal cells of the perch (Perca fluviatilis).
The whole-cell patch-clamp technique was employed to record membrane currents from isolated horizontal cells in culture. Concentration-response relationships for currents induced by L-glutamate, kainate and quisqualate were measured. Preincubation with dopamine changed the parameters of the concentration-response curves in a particular way for each agonist. The maximum currents induced by glutamate increased by 50-100% and the EC50-values were slightly shifted to higher values. The increase of kainate-induced maximum currents after dopamine incubation did not exceed 30% but the EC50-values were clearly shifted to lower concentrations. Quisqualate-induced maximum currents were not enhanced by dopamine preincubation but the EC50-values were shifted to lower concentrations. The dopamine-dependent modulation was affected by removal of magnesium and preincubation with concanavalin A and aniracetam. The concentration-response relation and the time-course of the dopamine effect on glutamate-induced currents is described.
Kruse
M
M
Physiologisches Institut, Justus-Liebig-Universität Giessen, Germany.
Schmidt
K F
KF
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005971:Glutamates / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D010471:Perches / Q000502:physiology*; D017470:Receptors, Glutamate / Q000187:drug effects; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*
D005971:Glutamates; D017470:Receptors, Glutamate; D003208:Concanavalin A; D007608:Kainic Acid; D004298:Dopamine