Table 2.

The effect of different experimental conditions on the kinetic parameters of I_SOC inactivation

Voltage	Parameter	Control (n = 15)	BAPTA (n = 4)	Sr2+ (n = 9)	Ba2+ (n = 7)	CaM mutant (n = 14)	CaM peptide (n = 10)
−118 mV	a1	0.25 ± 0.018	n.d.	n.d.	n.d.	0.19 ± 0.021*	0.18 ± 0.025*
	a2	0.32 ± 0.019	0.31 ± 0.027	0.48 ± 0.021	0.46 ± 0.016	0.31 ± 0.023	0.28 ± 0.023
	c	0.43 ± 0.016	0.69 ± 0.030	0.52 ± 0.020	0.54 ± 0.015	0.50 ± 0.020*	0.54 ± 0.021***
	τ1 (ms)	9.6 ± 0.9	n.d.	n.d.	n.d.	10.7 ± 1.2	11.5 ± 1.0
	τ2 (ms)	58 ± 5	59 ± 9	50 ± 8	60 ± 8	62 ± 7	67 ± 7
−138 mV	a1	0.35 ± 0.020	n.d.	0.15 ± 0.025***	0.20 ± 0.021***	0.24 ± 0.019**	0.26 ± 0.021**
	a2	0.29 ± 0.017	0.34 ± 0.025	0.38 ± 0.023**	0.37 ± 0.021*	0.31 ± 0.023	0.26 ± 0.020
	c	0.36 ± 0.019	0.66 ± 0.029	0.47 ± 0.020**	0.43 ± 0.020*	0.45 ± 0.018**	0.48 ± 0.023***
	τ1 (ms)	9.5 ± 1.0	n.d.	11.0 ± 1.3	14.0 ± 2.0*	7.9 ± 1.0	10.0 ± 1.2
	τ2 (ms)	62 ± 6	53 ± 9	47 ± 6	70 ± 9	51 ± 6	63 ± 8
−158 mV	a1	0.41 ± 0.017	0.12 ± 0.030***	0.24 ± 0.021***	0.28 ± 0.021***	0.26 ± 0.019***	0.29 ± 0.023***
	a2	0.28 ± 0.016	0.28 ± 0.030	0.30 ± 0.023	0.33 ± 0.020	0.30 ± 0.020	0.22 ± 0.020
	c	0.31 ± 0.016	0.60 ± 0.029***	0.46 ± 0.024***	0.38 ± 0.020*	0.44 ± 0.019***	0.49 ± 0.020***
	τ1 (ms)	8.1 ± 0.8	9.9 ± 1.2	8.3 ± 0.6	10 ± 1.1	6.9 ± 0.9	8.8 ± 1.0
	τ2 (ms)	59 ± 4	59 ± 9	41 ± 5	54 ± 6	42 ± 7	54 ± 5

The values are shown as the mean ± s.e.m. of the number experiments identified in brackets. a₁ and a₂ represent the relative amplitudes of the fast and slow exponential components, respectively, τ₁ and τ₂ are the time constants (ms) of these components, and c is the relative amplitude of the steady state component (eqn (1b)); n.d. – not detectable. Degrees of significance, determined by t test, are

^*P < 0.05

^**P < 0.01

^***P < 0.001