Resting and action potentials recorded by the sucrose-gap method in the superior cervical ganglion of the rabbit.
1. Evoked ganglionic action potentials and drug-induced changes in resting potential were recorded by the sucrose-gap method. The height of the action potential was 10-20 mV.2. Since the amplitude of the P wave is inversely proportional to the external potassium concentration between 0.5 and 12 mM, the P wave is probably caused by a phase of increased permeability to K(+).3. In the absence of an anticholinesterase, the depolarizing actions of choline and acetylcholine on the ganglion are almost equal, whereas acetylcholine is 2-3 times more potent than choline on the fibres of the internal carotid nerve. In the presence of eserine, acetylcholine induces a depolarization of the ganglion of up to 14 mV, while increase in [K(+)](o) causes a depolarization of up to 55 mV.4. Although the post-ganglionic fibres in the distal pole of the ganglion are depolarized by drugs, for example, acetylcholine, they contribute little to drug-induced potential changes and probably little to evoked action potentials.5. The hyperpolarization which occurs after exposure of the ganglion to acetylcholine is not due to a phase of increased permeability to K(+).
D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology; D004594:Electrophysiology; D005725:Ganglia, Autonomic / Q000187:drug effects*; D066298:In Vitro Techniques; D008564:Membrane Potentials; D008722:Methods; D010525:Peripheral Nerves / Q000187:drug effects; D010830:Physostigmine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D013395:Sucrose; D013564:Sympathetic Nervous System / Q000187:drug effects
D013395:Sucrose; D002217:Carbachol; D010830:Physostigmine; D002794:Choline; D000109:Acetylcholine; D011188:Potassium