Binding of Alpha-Bungarotoxin to Single Identified Neurons of 'Aplysia' which have Different Ionic Responses to Acetylcholine,
Abstract
Identifiable Aplysia neurons have one or more of three different ionic responses to acetylcholine, due to Na, Cl, and K conductance increases, respectively. The nature of the acetylcholine receptor mediating these three responses was studied using alpha-bungarotoxin. All three physiologic responses are blocked by alpha-bungarotoxin and I(125) alpha-bungarotoxin binds saturably to single neurons dissected from the ganglia. The apparent dissociation constant for I(125) alpha-bungarotoxin binding is not significantly different in neurons with different ionic response to acetylcholine. Most Na neurons, however, have a greater density of acetylcholine receptors. When studied electrophysiologically only the Na responses are blocked by hexamethonium. These observations are consistent with the view that Na, Cl, and K responses to acetylcholine are activated through a single class of acetylcholine receptors. The efficacy of hexamethonium in blocking toxin binding to all types of neurons suggests that it has a common binding site on all Aplysia acetylcholine receptors. Thus the inhibition of the Na response by hexamethonium may be a result of the binding to a site which prevent the conductance change rather than preventing acetylcholine from binding to its receptor.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1976
- Accession Number
- ADA033255
Entities
People
- D. O. Carpenter
- L. A. Greene
- W. G. Shain Jr.
Organizations
- Armed Forces Radiobiology Research Institute