FIGURE 2.

α5β1 integrin activation increases BK channel calcium sensitivity. A, conductance-voltage (G-V) relationships were determined from tail current amplitudes measured 0.2–0.3 ms after the step to the tail potential and normalized to the peak tail current. Normalized data were fit with single Boltzmann functions. Comparison of G-V relations in excised patches expressing mSlo in the absence (filled symbols) or presence (open symbols) of α5β1 integrin Ab as applied using protocol B. The number of patches for each group is given in parentheses. B, V_0.5 values plotted as a function of cytosolic free Ca²⁺ for cells with and without α5β1 integrin Ab. Consistent leftward shifts occurred following α5β1 integrin activation, except in 0 Ca²⁺. The value for the free [Ca²⁺] in 0 Ca²⁺ solution given here and in all subsequent plots of V_0.5 versus [Ca²⁺] is an estimate (i.e. 10 nm) and likely overestimates the actual [Ca²⁺] of the 0 Ca²⁺ bath. Asterisk indicates V_0.5 values that are significantly different (p < 0.05; determined by analysis of variance) from those of control patches (i.e. in the absence of integrin Ab).