Figure 3. Influence of 8-Br-cAMP on I_Ca in TG- and TG+ cells.

A, transient exposure to 8-Br-cAMP (300 μM) reversibly increased the peak I_Ca (activated by repeated 40 ms depolarizations to +10 mV) in a TG- cell. Typical Ca²⁺ channel currents shown above the plot were sampled at the points indicated by the arrows. B, mean current-voltage relationships for I_Ca in TG- cells before (Control) and after overnight (16-24 h) exposure to 8-Br-cAMP (n = 4-6). C, mean current-voltage relationships for I_Ca in TG+ cells in which overnight exposure to 8-Br-cAMP had no significant effect (P > 0.05; n = 6-18).