Channel-blocking activity is a possible mechanism for a selective ganglionic blockade.

The actions of bis-ammonium compounds (BAC) on the ionic channels activated by acetylcholine (ACh) were studied in voltage-clamped neurones of rabbit isolated superior cervical ganglion. The kinetics of binding of BAC to open channels was estimated from shortening of the decay of fast excitatory postsynaptic current. The kinetics of dissociation of BAC from open channels was estimated from the kinetics of restoring of second response to double-pulse application of ACh in presence of BAC. The ganglion-blocking activities of BAC correlated with the rate constants of their binding to open channels. It was concluded that selective ganglion-blocking actions of BAC were determined by their channel-blocking activities.