Fig. 1.

Effect of external pH changes on the SSC-increasing action of NMDA. Shown is continuous tracing of SSCs recorded from an innervated muscle cell in 1-d-oldXenopus culture. The myocyte was voltage-clamped at a potential of −60 mV. Downward deflections are SSCs (filtered at 150 Hz). The top right panel shows the relative position of patch pipette (R) and NMDA pipette (NMDA). Local perfusion of NMDA at the synaptic region with another micropipette increased SSC frequency. NMDA responses were potentiated in pH 8.6 Ringer’s solution and antagonized in pH 6.6 Ringer’s solution. Samples of superimposed SSCs in 1 sec before and after NMDA treatment are shown at higher time resolution. Scale bar, 40 μm. M, Myocyte; N, neuron.