The efflux of labeled and unlabeled potassium ions from the squid giant axon has been measured under a variety of experimental conditions. Axons soaked in sea water containing 42K ions lost radioactivity when placed in inactive sea water according to kinetics which indicate the presence of at least two cellular compartments. A rapidly equilibrating superficial compartment, probably the Schwann cell, was observed to elevate the specific activity of 42K lost from such axons to K-free sea water for a period of hours. The extra radioactive potassium loss from such axons during stimulation, however, was shown to have a specific activity identical within error to that measured in the axoplasm at the end of the experiment. The same was shown for the extra potassium loss occurring during passage of a steady depolarizing current. Axons placed in sea water with an elevated potassium ion concentration (50 mM) showed an increased potassium efflux that was in general agreement with the accompanying increase in membrane conductance. The efflux of potassium ions observed in 50 mM K sea water at different membrane potentials did not support the theory that the potassium fluxes obey the independence principle.
Article|
January 01 1967
Tracer and Nontracer Potassium Fluxes in Squid Giant Axons and the Effects of Changes in External Potassium Concentration and Membrane Potential
R. A. Sjodin,
R. A. Sjodin
From the Department of Biophysics, University of Maryland School of Medicine, Baltimore, and the Marine Biological Laboratory, Woods Hole, Massachusetts
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L. J. Mullins
L. J. Mullins
From the Department of Biophysics, University of Maryland School of Medicine, Baltimore, and the Marine Biological Laboratory, Woods Hole, Massachusetts
Search for other works by this author on:
R. A. Sjodin
From the Department of Biophysics, University of Maryland School of Medicine, Baltimore, and the Marine Biological Laboratory, Woods Hole, Massachusetts
L. J. Mullins
From the Department of Biophysics, University of Maryland School of Medicine, Baltimore, and the Marine Biological Laboratory, Woods Hole, Massachusetts
Received:
March 08 1966
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1967 by The Rockefeller University Press
1967
J Gen Physiol (1967) 50 (3): 533–549.
Article history
Received:
March 08 1966
Citation
R. A. Sjodin, L. J. Mullins; Tracer and Nontracer Potassium Fluxes in Squid Giant Axons and the Effects of Changes in External Potassium Concentration and Membrane Potential . J Gen Physiol 1 January 1967; 50 (3): 533–549. doi: https://doi.org/10.1085/jgp.50.3.533
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