Localization of the excitable membrane in the myelinated giant fiber of shrimp Penaeus japonicus.

A significant DC-potential was recorded from the axon of shrimp myelinated giant nerve fiber, using a dye-filled microelectrode. Tracing of the dye assured that the source of the potential was the axonal membrane. All-or-none action potentials were obtained in the same preparation from which the ends of the axon were removed except for the synaptic region. It was concluded that the functionally excitable membrane is localized only in the synaptic region.