Fig. 8. Glutamate induced-firing inhibition is mediated by intracellular Ca2+ rise.
(A) Simultaneous measurements of Ca2+ rises and firing inhibition upon glutamate uncaging in a dissociated dopamine neuron. Glutamate uncaging sites and Ca2+ measuring sites are marked as white circles (ø < 5 µM). Red triangles and blue boxes in the lower traces indicate uncaging points and firing pauses, respectively. (B) Local glutamate uncaging at different sites on proximal dendrites evoked Ca2+ spikes of similar amplitudes, and the evoked maximum firing frequencies did not differ significantly within the proximal dendritic regions (n = 7, *p < 0.05). (C) Postfiring pauses in spontaneous firing by glutamate uncaging in the proximal dendritic region decreased exponentially as a function of distance from the soma (n = 7). (D) Glutamate-induced firing inhibitions were blocked by apamin application (100 µM) and by dialysis with BAPTA (20 mM) using patch pipettes. The upper traces are firing changes (black), and the lower traces are dendritic Ca2+ changes (red). (E) Statistics from (D): glutamate uncaging, 13.01 ± 0.97 Hz, n = 9; apamin, 12.88 ± 1.55 Hz, n = 6; BAPTA, 15.03 ± 2.29 Hz, n = 3. Dendritic Ca2+ increases were completely inhibited by BAPTA dialysis. Values are presented as mean ± SE. *p < 0.05.
© Korean J Physiol Pharmacol
