Ionic Basis of the Photoresponse of Aplysia Giant Neuron: K+ Permeability Increase

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Science  17 Nov 1972:
Vol. 178, Issue 4062, pp. 755-756
DOI: 10.1126/science.178.4062.755


The giant neuron of the Aplysia abdominal ganglion hyperpolarizes during illumination. The light-initiated potential change is associated with an increase of membrane conductance. It reverses sign at the potassium equilibrium potential (about -83 millivolts), which was determined from direct measurements of internal potassium activity. The membrane hyperpolarization is produced entirely by a light-induced increase in potassium permeability.