Fig. 2.
Effects of Ca2+ channel blockers on the inhibitory action of dynorphin on mossy fiber responses. Single experiments showing typical records of mossy fiber field potentials before and after addition of 500 nm dynorphin. The time course of the change in mossy fiber responses is depicted in the corresponding bottom panels. Each trace is an average of 10 synaptic responses. Dynorphin was applied in normal Ringer’s solution (A), after 1 μm ω-CgTx (B), after 1 μm ω-Aga IVA (C), or after 10 μm CdCl2(D). Because ω-Aga IVA almost completely blocked mossy fiber responses to single stimuli, a brief 25 Hz stimulation train was used to restore synaptic transmission and the inhibitory effect of dynorphin after ω-Aga IVA or Cd2+ blockade of synaptic responses was assessed on the last response in the train.