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Effect of N-bromoacetamide on single sodium channel currents in excised membrane patches.
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MedLine Citation:
PMID:  6281357     Owner:  NLM     Status:  MEDLINE    
We have studied the effect of N-bromoacetamide (NBA) on the behavior of single sodium channel currents in excised patches of rat myotube membrane at 10 degree C. Inward sodium currents were activated by voltage steps from holding potentials of about -100 mV to test potentials of -40 mV. The cytoplasmic-face solution was isotonic CsF. Application of NBA or pronase to the cytoplasmic face of the membrane irreversibly removed sodium channel inactivation, as determined by averaged single-channel records. Teh lifetime of the open channel at -40 mV was increased about 10-fold by NBA treatment without affecting the amplitude of single-channel currents. A binomial analysis was used both before and after treatment to determine the number of channels within the excised patch. NBA was shown to have little effect on activation kinetics, as determined by an examination of both the rising phase of averaged currents and measurements f the delay between the start of the pulse and the first channel opening. Our data support a kinetic model of sodium channel activation in which the rate constant leading back from the open state to the last closed state is slower than expected from a strict Hodgkin-Huxley model. The data also suggest that the normal open-channel lifetime is primarily determined by the inactivation process in the voltage range we have examined.
J Patlak; R Horn
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of general physiology     Volume:  79     ISSN:  0022-1295     ISO Abbreviation:  J. Gen. Physiol.     Publication Date:  1982 Mar 
Date Detail:
Created Date:  1982-07-08     Completed Date:  1982-07-08     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985110R     Medline TA:  J Gen Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  333-51     Citation Subset:  IM    
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MeSH Terms
Acetamides / pharmacology*
Action Potentials
Biological Transport, Active / drug effects
Cell Membrane / metabolism
Ion Channels / metabolism*
Membrane Potentials
Muscles / metabolism*,  physiology
Sodium / metabolism*
Stimulation, Chemical
Grant Support
Reg. No./Substance:
0/Acetamides; 0/Ion Channels; 7440-23-5/Sodium; 79-15-2/N-bromoacetamide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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Journal Information
Journal ID (nlm-ta): J Gen Physiol
ISSN: 0022-1295
ISSN: 1540-7748
Publisher: The Rockefeller University Press
Article Information
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Print publication date: Day: 1 Month: 3 Year: 1982
Volume: 79 Issue: 3
First Page: 333 Last Page: 351
ID: 2215759
Publisher Id: 82191556
PubMed Id: 6281357

Effect of N-bromoacetamide on single sodium channel currents in excised membrane patches

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