Figure 7. Inhibition of mitochondrial Ca²⁺ extrusion with CGP-37157 reduces post-tetanic evoked release in near-physiological conditions (A), with reduced temperature and fewer stimuli (B) and in low bath [Ca²⁺] (C).

A–C, EPP amplitudes (normalized to EPP amplitude before the train) during and after 50-Hz stimulation. Error bars indicate s.d. Insets in the lower right of A and C show the difference between post-tetanic EPP amplitudes recorded in the absence and presence of CGP-37157. Mono-exponential decays (solid line) fitted to these data had time constants of 10.5 s in A (95% confidence interval, 8.8–12.1 s) and 22.6 s in C (95% confidence interval, 9.8–35 s). D, shows tetanic EPPs from C on an expanded time scale to show effects of CGP-37157 during the train. Curves are the weighted average of nine nearest neighbours. In all experiments muscle contractions were blocked with 2.5–4 μmμ-conotoxin GIIIB. Data in A were averaged from 17 trains recorded from 12 endplates in control (○), and from 12 trains in 10 terminals after addition of CGP-37157 (•). Data in B are the average of three control and six post-drug trains from the same terminal. Data in C and D are the average of 12 trains from 12 terminals in four animals (control) and 10 trains from 10 terminals (drug).