FIGURE 7.

Ca_v1.2_33L channels yield dominant negative effect on Ca_v1.3 channels but not on Ca_v3.2 channels. Ca_v1.2_33L channels were cotransfected with Ca_v1.3 or Ca_v3.2 channels at a ratio of 1:1. I-V curves were obtained in a bath solution containing 1.8 mm Ca²⁺. As a control, pcDNA3 vectors were transfected at the same molar ratio. A, in Ca_v1.3 channels, which require β subunits, Ca_v1.2_33L channels greatly inhibited Ca_v1.3 currents. At −10 mV, the reduction of current density from −16.16 ± 2.205 pA/pF (n = 8) to −7.952 ± 1.250 pA/pF (n = 15), p = 0.0021, Student's t test, represents an almost 50% decrease. B, Ca_v1.2_33L cotransfection had no effect on Ca_v3.2 channels, which do not require β subunits.