Fig. 2. Effect of DNQX and GAMS on sustained excitation of cell 204 by cell tr1. a. Control: In normal physiological saline, intracellular cell Tr1 stimulation elicits prolonged membrane depolarization of cell 204 and swimming. DNQX: Cell Tr1 loses its ability to excite cell 204 and to trigger swimming in the presence of 200 mM DNQX. Cell Tr1 also continues to activate the DP nerve, although to a lesser extent than in the control recording. Wash: Sustained excitation of cell 204 by cell Tr1 stimulation is restored when the nerve cord is returned to normal physiological saline. b. Control is as described above. GAMS: The cell Tr1-induced excitation of cell 204 is slightly reduced in the presence of 100 mM GAMS. Note that cell 204's firing frequency continues to increase and its membrane potential to elevate, following cell Tr1 stimulation. [a] and [b] are from different experiments. CALIBRATION: 4 mV (cell 204) and 20 mV (cell Tr1), 2 s.