A method for recording agonist-induced depolarizations in small autonomic ganglia

A convenient extracellular method is reported for recording from autonomic ganglia as small as the chick ciliary ganglion. This technique allows recording of both the compound action potentials arising from synaptic transmission through the ganglion and ganglion depolarizations due to such agents as carbachol or potassium. A perfusion system is also described that allows rapid introduction and removal of pharmacological agents. The principal advantages of the technique are two-fold: (1) the method is simple and should work for any small ganglion as long as recordings can be made from the postganglionic nerve using a suction electrode; (2) the rapid introduction and removal of agonists allows frequent measurements of ganglionic depolarization with little receptor desensitization.