Fig. 11. The opener inhibitor (OI) and the common inhibitor (CI) are similarly effective in inhibiting synaptic and contractile responses to stimulation of the excitor OE. (A) Intracellular recordings of synaptic responses to identical stimulus trains (10 Hz, 600 ms) delivered to OE alone, OI and OE (stimulated simultaneously), CI and OE (stimulated simultaneously) and OE alone. Both inhibitors inhibit excitatory junction potential (EJP) amplitude and hyperpolarize muscle slightly. The broken line illustrates resting membrane potential. (B) Tension recordings corresponding to stimulus trials above. Note that the muscle contracts in response to stimulation of OE alone but fails to contract if either inhibitor is stimulated. The broken line indicates resting level of muscle tension in the absence of stimulation. Scale bar, 2.5 mg, 100 mg, 500 ms.