A, sample traces showing IJPs at 0.5, 5 and 20 Hz in control conditions (Aa), following addition of l-NNA (300 μm; Ab) and with MRS2500 (1 μm) plus l-NNA (Ac). B, sample trace from a different muscle showing the IJPs generated in the presence of MRS2500 alone. C, summary graph of area during EFS (mV-s(4 s)-1) in control conditions (filled squares), following addition of l-NNA (filled triangles) or MRS2500 (inverted filled triangles) or with combined MRS2500 and l-NNA (filled circles). Inhibitory junction potentials were significantly reduced in the presence of MRS2500 alone (*p<0.05) and further reduced with combined MRS2500 and l-NNA (#p<0.05). Shown are mean values ± SEM; n = 5–8. One-way ANOVA with Tukey's post hoc test.