The Journal of General Physiology, Vol 60, 519-533,
Copyright © 1972 by The Rockefeller University Press
Active Transport of Potassium by the Giant Neuron of the Aplysia Abdominal Ganglion
J. M. Russell 1 and
A. M. Brown 1
1 From the Departments of Pharmacology, Physiology, and Medicine, University of Utah College of Medicine, Salt Lake City, Utah 84112
We measured the internal potassium activity, aiK, and membrane potential, Em, simultaneously in 111 R2 giant neurons of Aplysia californica. aiK was 165.3 ± 3.4 mM, Em was -47.8 ± 0.9 mv, and EK 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, aiK fell exponentially after the following treatments: cooling to 0.5°–4°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.
Submitted on March 27, 1972
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