Publication

Effects of barium on the potassium conductance of squid axon

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Last modified
  • 06/25/2025
Type of Material
Authors
    Douglas Eaton, Emory UniversityMalcolm S. Brodwick, University of Texas Galveston
Language
  • English
Date
  • 1980-01-01
Publisher
  • ROCKEFELLER UNIV PRESS
Publication Version
Copyright Statement
  • © 1980, Rockefeller University Press., All rights reserved.
License
Final Published Version (URL)
Title of Journal or Parent Work
Volume
  • 75
Issue
  • 6
Start Page
  • 727
End Page
  • 750
Grant/Funding Information
  • This work was supported by National Institutes of Health grant 2R01-NS-11963 to Doctors Brodwick and Eaton, and grant IR01-AM-20068 and Research Career Development Award 1K04-AM-00432 to Dr. Eaton.
Abstract
  • Ba++ ion blocks K+ conductance at concentrations in the nanomolar range. This blockage is time and voltage dependent. From the time dependence it is possible to determine the forward and reverse rate constants for what appears to be an essentially first-order process of Ba++ interaction. The voltage dependence of the rate constants and the dissociation constants place the site of interaction near the middle of the membrane field. Comparison of the efficacy of Ba++ block at various internal K+ concentrations suggests that Ba++ is probably a simple competitive inhibitor of K+ interaction with the K+ conductance. The character of Ba++ block in high external K+ solutions suggests that Ba++ ion may be "knocked-off" the site by inward movement of external K+ Examination of the effects of other divalent cations suggests that the channel may have a closed state with a divalent cation inside the channel. The relative blockage at different temperatures implies a strong interaction between Ba++ and the K+ conductance.
Author Notes
  • We would like to thank Ms. Sandy Carreon and Ms. Teri Cherry for their excellent assistance in the preparation of this manuscript. We would also like to thank Ms. Jan Scott for technical assistance. We are indebted to Dr. Harvey Fishman who provided us with laboratory space, a great deal of laboratory equipment, and much helpful advice and discussion. Similarly, we are also indebted to Doctors William Adelman, Jr., and Toshio Narahashi for encouragement and helpful suggestions as well as Doctors Paul Adams and Robert French for reading and commenting on the manuscript.
Keywords
Research Categories
  • Biology, Physiology

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