Table I.

Slope parameters (Δα) extracted from ensemble current analyses

Constructs	[Ca2+]	Slope parameter Δα (mean ± SD)	No. of patches
	M	mmHg−1
WT	10−3	0.015 ± 0.0043	4
WT	10−5	0.016 ± 0.0050	6
WT	10−6	0.018 ± 0.0031	4
358–486-12GGS	10−5	0.012 ± 0.0033	4

The ensemble current plots of P_o versus pressure from wild type at different [Ca²⁺] (10⁻⁶, 10⁻⁵, and 10⁻³ M) and 358–486-12GGS at intermediate [Ca²⁺] (10⁻⁵ M) were fitted with the Boltzmann equation: P_o = 1/[1 + a × exp(−Δα × P)] (Fig. 1 B). The slope parameters, Δα, of the wild type at different [Ca²⁺] are not significantly different (P = 0.38, 0.28, and 0.28 in a pairwise t test). Δα of 358–456-12GGS is also not significantly different from that of the wild type at 10⁻⁵ M Ca²⁺ (P = 0.07).