CADMIUM INHIBITS STIMULUS-RESPONSE COUPLING IN SKATE (RAJA-ERINACEA) ELECTRIC ORGAN

1. The effects of cadmium on stimulus-response coupling in the skate (Raja erinacea) electric organ were examined. 2. Cadmium decreased the evoked electrical discharge and the evoked release of H-3-ACh in a concentration-related fashion. 3. Cadmium (100 muM) also blocked voltage-dependent Ca-45 uptake. 4. Both d-tubocumrine and nifedipine blocked Ca uptake and evoked potential, but not H-3-ACh release, thus most of the Ca-45 uptake measured was post-synaptic through L Ca channels. 5. Nickel. cadmium, and verapamil inhibited H-3-ACh release and evoked potential, indicating a block of pre-synaptic T Ca channels.