The triphasic response of the isolated superior cervical ganglion of the rat to cholinergic stimulants

The moving fluid electrode technique was used on the isolated rat superior cervical ganglion to investigate changes of potential elicited by drugs independently of induced action potentials. The existence of 3 distinct phases was confirmed. These comprise, firstly, a strong depolarization which is predominantly nicotinic in origin: this is succeeded by a hyperpolarization which does not represent a compensatory recovery process although it, too, is essentially nicotinic. Further evidence is presented to support the concept that catecholamines may be involved at this stage. The last phase is a slow but significant depolarization, and this is wholly muscarinic in nature.