FIGURE 8.

The A-type VGKC inhibitor, 4-AP mimics S100B-mediated increases in intrinsic APs and L-type VGCC-mediated Ca²⁺ flux frequencies in midbrain neurons. (a) Representative traces of AP recordings from TH⁺ and TH⁻ neurons with acute application of 100 μM 4-AP. (b) Average AP frequency of TH⁺ and TH neurons with and without 4-AP; fold change for each TH⁺ and TH⁻ neuron is shown in the graphs below. n = 10 for TH⁺ neurons and 9 for TH⁻ neurons from two independent weeks of culture. All errors are SEM; p-values are based on paired sample t tests for TH⁺ spontaneous, TH⁺ 4-AP and TH⁻ spontaneous, TH⁻ 4-AP or two sample t tests for TH⁺ spontaneous, TH⁻ spontaneous. (c) Representative Ca²⁺ traces of TH⁺ and TH⁻ neurons with bath application of 4-AP, followed by co-application of 4-AP + diltiazem, the red line represents the average Ca²⁺ activity from all neurons of that cell type. (d) Graphs of average area under the curve with bath application of 4-AP, followed by co-application of 4-AP + diltiazem. n = 16 for TH⁺ neurons and 14 for TH⁻ neurons from two independent weeks of culture. All errors are SEM; p-values for TH⁺ neurons are based on Wilcoxon signed-rank tests, and paired sample t tests for TH⁻ neurons