RT Journal Article
SR Electronic
T1 The action of cholinergic agonists on the squid stellate ganglion giant synapse
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1904
OP 1911
DO 10.1523/JNEUROSCI.04-07-01904.1984
VO 4
IS 7
A1 EF Stanley
YR 1984
UL http://www.jneurosci.org/content/4/7/1904.abstract
AB Although the giant synapse in the squid stellate ganglion has served as a model in the understanding of the ionic and electrical changes that occur during the release of transmitter from nerve terminals, little is known about the pharmacology of this synapse or the identity of its neurotransmitter. In the present study, the suggestion that acetylcholine (ACh) is the excitatory transmitter at this synapse was tested by exploring the actions of cholinergic agents on the pre- and postsynaptic giant axons and on the excitatory postsynaptic potential (EPSP). A novel arterial perfusion technique that circumvents the diffusion barrier from the bathing medium to the synapse has been used to demonstrate a depolarizing action of ACh and its agonist carbachol on the post- but not the presynaptic axon. The cholinergic receptors are distinct from receptors activated by amino acids, such as glutamate, have a reversal potential of about -48 mV, are anion- permeable, and desensitize without blocking the EPSP. It is concluded that these receptors are involved in an inhibitory input onto the postsynaptic giant axon and, therefore, that ACh is most probably not the transmitter at the squid giant synapse.