Figure 3.

Ba²⁺ acts as a weak agonist for CDI of Ca_V1.2 channels in tsA201 cells. A, Top, Recordings of Na⁺ current (green) evoked by 500 ms depolarization from −80 to −10 mV in cells in which AKAP79 was overexpressed either alone (79) or with CaN_H151A. Control Ca_V1.2 Ca²⁺ (light gray) and Ba²⁺ (dark gray) current records reproduced from Figure 2A. Ca²⁺, Ba²⁺, and Na⁺ currents are shown scaled to the same peak inward current amplitude. Bottom, Inactivation rates measured for Ca²⁺ (light gray bar), Ba²⁺ (dark gray bar), and Na⁺ (green bars) currents carried by Ca_V1.2 channels in cells overexpressing AKAP79 (79) or AKAP79 and CaN_H151A. Ca²⁺ and Ba²⁺ data reproduced from Figure 2A. B, Families of Ca²⁺, Ba²⁺, and Na⁺ currents through Ca_V1.2 channels, recorded over a range of test potentials that elicited inward current in cells overexpressing AKAP79. C, For Ca²⁺, Ba²⁺, and Na⁺ currents carried by Ca_V1.2 channels, inactivation rates obtained over a range of test potentials applied to cells overexpressing AKAP79. No forskolin was used in the experiments.