An Electrophysiological Study of Ganglion Blockade by Paraquat and Diquat

1 The bipyridilium herbicides, particularly paraquat, have chemical and toxicological features in common with the bi-quaternary ammonium ganglion blockers. 2 Paraquat and diquat were tested for ganglion blocking activity. Rabbit cervical ganglia were superfused with both agents and subsequently with hexamethonium to confirm susceptibility to ganglion blockade. 3 No evidence for ganglion blockade was found at either supra maximal or sub maximal stimulation, and none following repetitive stimulation. 4 The similarities and differences between the bipyridyl herbicides and bi-quaternary ganglion blockers can be explained on the basis of their structures. 5 It is concluded that neither paraquat nor diquat have significant ganglion blocking activity.