Figure. 4. CDI of neuronal L-type Ca²⁺ channels is reduced by PKA pathway activation.

(A) Internal perfusion with forskolin slows Ca²⁺-dependent inactivation of L-type current and increases current density. Peak Ca²⁺ current amplitude (red) was normalized to peak Ba²⁺ current (black) amplitude. Bar graphs present inactivation rates for Ca²⁺ and Ba²⁺ currents; number of individual cells recorded (n) is marked on each bar.

(B) Bath application of 100 μM cAMP analog (Sp-5,6-dichloro-cBIMPS) (bottom), but not 10 μM Sp-5,6-dichloro-cBIMPS (top), enhances current density and slows Ca²⁺-dependent inactivation. Error bars indicate standard error of the mean. Mean values were compared using ANOVA with a Bonferroni posthoc correction. Statistical significance marked as * p = 0.05, **** p = 0.001.