Table 3.

Inhibition by µ-SIIIA of cloned sodium channels expressed in Xenopus oocytes. Rate constants were determined as described under Experimental. Standard deviation and 95% confidence intervals (95% C.I) were calculated from at least three independent experiments using Prism software.

Sodium channela	kon (µM−1.min−1)	koff (min−1)	IC50(95% C.I.) (µM)
rNaV1.1	0.011 ± 0.004	0.2 ± 0.06	11 (9.3–12.6)
rNaV1.2	0.10 ± 0.015	Irreversibleb	N.A.c
rNaV1.3	0.017 ± 0.002	0.12 ± 0.018	11 (9.0–12.9)
rNaV1.4	0.29 ± 0.036	0.04 ± 0.008	0.13 (0.11–0.16)
rNaV1.5	--d	--d	251 (204–308)e
mNaV1.6	0.06 ± 0.012	0.082 ± 0.006	0.76 (0.69–0.85)
rNaV1.7	0.005 ± 0.0005	0.075 ± 0.012	65 (57.8–73.1)

^aα-Subunit cloned from rat (r) or mouse (m).

^bAlthough the block was essentially irreversible within the experimental time frame, the k_off was estimated as 0.0047 ± 0.0015 min⁻¹ based on residual recovery after 20 min of wash and assuming exponential decay.

^cNot available because slow kinetics precluded steady state from being achieved within the experimental time frame.

^dUnable to be determined because block was too small and apparent kinetics too fast to be measured accurately.

^eExtrapolated value assuming 100% block at saturating peptide concentration.