Figure 4
Mg2+ block of Ca v 2.3 channels expressed alone and co-expressed with SmCa v β or Ca v β 2a . Current-voltage relationships from HEK cells expressing Cav2.3 subunits alone (A), co-expressing Cav2.3 and SmCavβ subunits (B) or co-expressing Cav2.3 and Cavβ2a subunits (C) in minimal intracellular solution (filled circles) and in intracellular solution containing 5 mM MgCl2 (open circles). Peak currents generated by voltage steps from -20 mV to +75 mV in 5 mV steps from a holding potential of -80 mV are plotted. Data points represent mean ± s.e.m. D. Peak current amplitude in the presence of 5 mM internal MgCl2 relative to peak current amplitude in the absence of MgCl2 for Cav2.3 subunits alone, co-expressed with SmCavβ subunits or co-expressed with Cavβ2a subunits. Asterisks denote statistically significant difference with respect to Mg2+ block of Cav2.3 channels alone (p < 0.05), N = 5 – 7.