Optical recording of action potentials from vertebrate nerve terminals using potentiometric probes provides evidence for sodium and calcium components.
Optical methods are shown to monitor action potentials from a population of nerve terminals in the neurohypophysis of Xenopus. Calcium antagonists such as cadmium and nickel ions block a component of the action potential that probably reflects a calcium-mediated potassium conductance, and tetrodotoxin blocks an inward sodium current, revealing a calcium component to the action potential upstroke.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology; D009532:Nickel / Q000494:pharmacology; D010904:Pituitary Gland, Posterior / Q000502:physiology*; D012964:Sodium / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014982:Xenopus laevis
D002104:Cadmium; D013779:Tetrodotoxin; D009532:Nickel; D012964:Sodium; D002118:Calcium