Fig. 4.

Cadmium ion antagonism of the release-enhancing effects of high-Ca solution, high-K solution, or 4-AP in wild-type preparations at 21–22°C. In these experiments, the initial record inA–C is the control situation before addition of: A, high-Ca solution; B, high-K solution; and C, 4-AP. The second record in each series shows the release-enhancing effect of each of these treatments. The third record indicates what happens when 1 mm Cd is added to the bath solution. In A and C, we measured evoked responses, whereas in high K (B), only spontaneous events were recorded. In our experience, 1 mm Cd not only abolished the stimulus-evoked responses in A and C, but it also considerably reduced mejp frequency in this preparation, as indicated in B.