title: Active transport of potassium by the giant neuron of the aplysia abdominal ganglion.
abstract: We measured the internal potassium activity, a(i) (K), and membrane potential, E(m), simultaneously in 111 R2 giant neurons of Aplysia californica. a(i) (K) was 165.3 +/- 3.4 mM, E(m) was -47.8 +/- 0.9 mv, and E(K) calculated using the Nernst equation was -76.9 +/- 0.05 mv. Such values were maintained for as long as 6 hr of continuous recording in untreated cells, a(i) (K) fell exponentially after the following treatments: cooling to 0.5 degrees -4 degrees C, ouabain, zero external potassium, 2,4-dinitrophenol, and cyanide. The effects of cooling and zero potassium were reversible. Potassium permeability was calculated from net potassium flux using the constant field equation and ranged from 2.6 to 18.5 x 10(-8) cm/sec. We conclude that potassium is actively transported into this neuron against a 30-40 mv electrochemical gradient.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D003080:Cold Temperature; D003486:Cyanides / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D008974:Mollusca / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012623:Seawater
chemical_list: D003486:Cyanides; D004140:Dinitrophenols; D010042:Ouabain; D011188:Potassium