Figure 8. K_V1 current is insensitive to α-dendrotoxin and margatoxin in rat cerebral VSMCs.

A, potassium currents generated by 8 mV depolarizing steps from −70 to +58 mV were only slightly reduced by α-dendrotoxin (α-DTX, 100 nM) and margatoxin (MgTX, 100 nM). Both drugs block K_V1.2 homotetramers, but not K_V1.5 homotetramers or K_V1.2/1.5 heterotetrameric channels. The addition of 1 μM correolide (COR) reduced the same current. B, I-V relations averaged from six cells demonstrate the relative toxin-insensitivity of K⁺ currents in cerebral VSMCs, but the sensitivity of the same currents to block by COR. Data are expressed as means ±s.e.m. (n = 6). * Significant difference (P < 0.05) between control and experimental values at the same voltage.