Responses to glutamate (Glut) in myenteric neurons are direct and not attributable to the release of another neurotransmitter. 1, Microejection of glutamate onto a 2/AH neuron causes a fast response (arrowhead, Control) that is not inhibited by a low-Ca²⁺/high-Mg²⁺-containing solution. The cell spikes repetitively in the low-Ca²⁺/high-Mg²⁺-containing solution because a Ca²⁺-activated K⁺ conductance contributes to the RMP of 2/AH cells, which become depolarized in the absence of Ca²⁺.2, Superfusion with TTX has no effect on glutamate-induced depolarizations recorded in a 2/AH neuron. Note that Ca²⁺ spikes are observed in the presence of TTX.