FIGURE 4.

Many myenteric neurons exhibited [Ca²⁺]_i transients in response to L-Glu and NMDA. (A) Representative fluorescence micrographs of NMDA (100 mM) evoked [Ca²⁺]_i transients in myenteric neurons (filled arrowheads) and glia (open arrowheads) [GCaMP3 signal at rest (t = 0 s) and during NMDA spritz in neurons (t = 3.5 s) and in glia (t = 5.5 s)]. (B) Example traces from a neuron (1) and a glial cell (2; marked in A) that responded to L-Glu. Glial cell shows delayed response to NMDA compared to the GCaMP3+ neuron. Arrow indicates NMDA application. (C) Representative fluorescence micrographs of L-Glu (50 mM) and NMDA (100 mM) evoked [Ca²⁺]_i transients in myenteric neurons [GCaMP3 signal at rest (t = 0 s) and during L-Glu stimulation and NMDA stimulation, respectively]. Most L-Glu responding neurons also respond to NMDA (filled arrowhead). Some neurons either respond to L-Glu (orange arrowhead) or NMDA (blue arrowhead). (D) [Ca²⁺]_i transient traces obtained from neuron 1 and neuron 2 (marked in C). Arrow indicates drug application. Histograms showing pooled [Ca²⁺]_i transient amplitudes from all neurons stimulated with NMDA (E) and L-Glu (F), and from L-Glu responding neurons stimulated with 1 pulse (G) and 20 pulse (H) in time control (con) and in the presence of APV. Changes in amplitude after application APV are presented as a percentage of the first response in control saline (% Δ F_i/F₀). APV did not alter the amplitude of agonist or electrically evoked [Ca²⁺]_i transients in myenteric neurons. All scale bars 50 μm. Number of neurons examined are indicated on the bar graphs.