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. 2005 Sep 21;25(38):8735–8745. doi: 10.1523/JNEUROSCI.2119-05.2005

Figure 2.

Figure 2.

BDS-I and BDS-II toxins inhibit Kv3.1a currents in a concentration- and voltage-dependent manner. A, Exemplar current recordings at +40 mV from a mouse fibroblast (B82) cell stably expressing homomeric Kv3.1a channel subunits, under control conditions and when stably blocked by 50–1000 nm BDS-I. Note also slowing of the activation rate, which becomes more marked as concentration increases. B, Concentration–response curves of peak Kv3.1a current inhibition (measured at +40 mV) by various concentrations of BDS-I (open squares) and BDS-II (open circles). Plots were fitted with a logistic function, described as follows: response = maximum response/[1 + (IC50/concentration)]. Calculated IC50 values from these curves were 220 and 750 nm for BDS-I and BDS-II, respectively. C, Fractional inhibition of peak Kv3.1 current by 50, 300, and 500 nm BDS-I depends on step voltage. I is peak outward current in toxin, and Io is current amplitude in the absence of toxin. D, Inhibition of peak outward current by 500 nm BDS-I and BDS-II on both Kv3 subtypes shows steep voltage dependence.