Beta-bungarotoxin inhibits a non-inactivating potassium current in guinea pig dorsal root ganglion neurones

beta-Bungarotoxin (beta-BuTx), at concentrations of 0.45-45 nmol/l, selectively reduced a portion of the noninactivating potassium current (IsK) in dorsal root ganglion neurones of the guinea pig, measured by voltage clamp of internally perfused cells. The average reduction of IsK obtainable with beta-BuTx was 34% and usually not completed within 20 min, but irreversible upon washing for 20 min. The I/V-characteristic of the current blocked by beta-BuTx was almost linear. It is suggested that beta-BuTx selectively blocks a noninactivating subtype of potassium channel.