Fig. 2.

Effect of Ctx on presynaptic Δ[Ca²⁺] and EPSC. A, Ctx (1 μm) reduced both the Δ[Ca²⁺] and the EPSC evoked by single presynaptic action potentials with a similar time course. Amplitudes of both the Δ[Ca²⁺] and the EPSC were normalized to the values during the control period.B, Sample traces of the presynaptic Ca²⁺ influx (left), the presynaptic action potential (top right), and the EPSC (bottom right) before (a) and after (b, as indicated in A) Ctx application. The stimulus was given at time 0. C, EPSCs plotted against the Δ[Ca²⁺] fromA on double logarithmic scales. The slope of the linear regression line was 1.3. D, Summary of the effect of Ctx on the Δ[Ca²⁺] and the EPSC. Each value was obtained from 3–11 cells. The effects of Ctx at 1 and 3 μm were not significantly different (p > 0.5; t test).