The responses to ganglionic stimulating and blocking drugs of cell groups within a sympathetic ganglion.

Time effects of a number of ganglionic blocking and stimulating drugs on evoked postganglionic action potentials of distinct cell groups within the superior cervical ganglion were studied with conventional electrophysiological techniques. The response of one cell group was observed consistently to be relatively resistant to the effects of both classes of drugs. Furthermore, the action potential of this group, unlike other ganglion cell groups, evoked by submaximal preganglionic volleys was not potentiated by the anticholinesterase agent, di iso propyl phosphorofluoridate (DFP). Although these findings may he considered compatible with the concept of functional heterogeneity within the superior cervical ganglion, the possibility of irregular distribution of the drugs within the ganglion cannot be dismissed.