Table 1.

Rates of block of rI_Na and control I_Na by the various guanidinium alkaloids, corresponding to k_AC and k_RB of Fig. 1C, respectively

	Apparent kon, μM−1·min−1†
Alkaloid	rINa With KIIIA	rINa With KIIIA [K7A]	Control INa	Reference
TTX	0.003 ± 0.0004	0.56 ± 0.08	58 ± 5.3	Zhang et al. (2009)
STX	∼0‡	0.65 ± 0.10	254 ± 41.0	Thisstudy
GTX2/3	∼0‡	0.55 ± 0.03	113 ± 8.7	Thisstudy

Values are means ± SD, n ≥3 oocytes.

^†Rate constants were obtained from slopes of curves in Fig. 3.

^‡No block of the rI_Na with KIIIA was discernable at the highest alkaloid concentration tested (10 μM, Fig. 2C), indicating a k_on at least tenfold smaller than that of TTX.