Hemicholinium-3: noncholinergic effects on squid axons.

Hemicholinium-3, when applied to the inside of a squid axon, is effective in blocking the action potential. This action is not antagonized by the addition of choline or acetylcholine to the perfusate. Voltage-clamp experiments show that hemicholinium-3 depresses both the early transient and late steady-state components of membrane ionic conductances, with a greater effect on the peak transient component.