title: Extracellular calcium, magnesium, and sodium ion competition in the conductance control of the photosensory membrane of Limulus ventral nerve photoreceptor.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D004553:Electric Conductivity; D005110:Extracellular Space / Q000502:physiology; D006737:Horseshoe Crabs; D007473:Ion Channels / Q000502:physiology; D008027:Light; D008274:Magnesium / Q000502:physiology*; D008564:Membrane Potentials; D010786:Photoreceptor Cells / Q000502:physiology* / Q000648:ultrastructure; D012964:Sodium / Q000502:physiology*
chemical_list: D007473:Ion Channels; D012964:Sodium; D008274:Magnesium; D002118:Calcium