Fig. 8. Inhibition of excitatory transmission by the opener inhibitor (OI) and the common inhibitor (CI). (A) Examples of synaptic responses of a single muscle fiber to stimulation of the opener excitor (OE) alone, CI and OE (interstimulus delay 8.9 ms) and OI and OE (interstimulus delay 15.1 ms). Scale bar, 2 mV, 200 ms. (B) EJP amplitude plotted as a function of interstimulus interval between OE and each of the two inhibitors. All measurements are from a single muscle fiber; excitatory junction potential (EJP) size is normalized to its size in control trials where only OE was stimulated. (C,D) EJP amplitude, normalized to control, plotted as a function of the interstimulus delay between OE and OI (C, N=14 fibers) and OE and CI (D, N=8 fibers). Symbols represent the mean values, vertical error bars represent standard deviations of the means, and horizontal error bars indicate the range of interstimulus intervals in each bin. *Data are significantly different (P<0.05) from controls where the excitatory axon was stimulated prior to the inhibitory axon.