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Analysis of sodium and potassium redistribution during sustained permeability increases at the innervated face of Electrophorus electroplaques

Lester, Henry A. (1978) Analysis of sodium and potassium redistribution during sustained permeability increases at the innervated face of Electrophorus electroplaques. Journal of General Physiology, 72 (6). pp. 857-862. ISSN 0022-1295. PMCID PMC2228490. http://resolver.caltech.edu/CaltechAUTHORS:LESjgp78

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Abstract

Cholinergic agonists cause an increase in the membrane permeability of Na and K at the innervated face of Electrophorus electroplaques. Therefore, sustained exposure to agonist reduces Na and K concentration gradients. There gradients are monitored with voltage-clamp sequences and pharmacological treatments that selectively measure the Nernst potentials for individual ions. EK is normally near--90 mV but moves toward zero during bath application of agonist. Depolarizations by bath- applied agonist measure primarily this shift of EK, not short- circuiting of EK by the agonist-induced conductance. After a rapid jump of agonist concentration, there is a fast (millisecond) depolarization due to the conductance increase, followed by a much slower additional "creep" due to the shift in EK. Sodium replaces the lost intracellular potassium: ENa, normally very positive, also moves toward zero. The shifts in EK and ENa are normally reversible but become permanent after blockade of the Na-K pump. In the presence of agonist, the shifts can be driven further by passing current of the appropriate polarity. Similar ion redistribution occurs with other drugs, such as batrachotoxin and nystatin, which induce prolonged increases in Na permeability. The redistributions cause little net change in the reversal potential of the neurally evoked postsynaptic current.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://www.jgp.org/cgi/content/abstract/72/6/847PublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228490/PubMed CentralArticle
ORCID:
AuthorORCID
Lester, Henry A.0000-0002-5470-5255
Additional Information:© 1978 by The Rockefeller University Press. RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode. Received for publication 24 March 1978. I thank D. Armstrong, P. Ascher, M. Brodwick, J-P. Changeux, J.B. Cohen, D.D. Koblin, M.M. Nass, J-L. Popot, R.E. Sheridan, F. Strumwasser, and D. Van Essen for helpful discussion. E.X. Albuquerque supplied a sample of batrachotoxin. This research was supported by the National Institutes of Health (Research Grant NS-11756 and Research Career Development Award NS-272) and by a grant from the Muscular Dystrophy Association.
Funders:
Funding AgencyGrant Number
NIHNS-1175
NIHNS-272
Muscular Dystrophy AssociationUNSPECIFIED
Issue or Number:6
PubMed Central ID:PMC2228490
Record Number:CaltechAUTHORS:LESjgp78
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LESjgp78
Usage Policy:RUP grants the public the non-exclusive right to copy, distribute, or display the Work under a Creative Commons Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ and http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode.
ID Code:11552
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:04 Sep 2008 06:30
Last Modified:09 Nov 2017 00:20

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