Fig. 4.

Reversible and irreversible induction of PDS. a, b Collectively, isradipine proved ineffective in suppressing BayK-induced PDS, as shown in a for event area and in b for PDS1000 (n = 10). c–f However, closer inspection of the data revealed the existence of two populations of neurons: one where PDS induction by BayK was moderate (group 1, n = 5) and fully inhibited after addition of isradipine (c, d) and another one (group 2, n = 5) where BayK led to pronounced appearance of PDS, an effect that was hardly reduced after exchange of BayK for isradipine (e, f). *** and ** above the error bars indicate P ≤ 0.001 and P ≤ 0.01, respectively, for statistical comparison of the marked data versus control using repeated measures ANOVA followed by Dunnett’s multiple comparison test. In a further comparison of all columns using repeated measures ANOVA with Tukey’s multiple comparison test, statistical difference was also examined between the caffeine + BayK and the caffeine + isradipine data (horizontal brackets): n.s. indicates a lack of statistical difference and **significant difference with P ≤ 0.01