help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS

Biophysical Journal 58: 1169-1181 (1990)
© 1990 the Biophysical Society

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ruben, P C
Right arrow Articles by Rayner, M D
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ruben, P C
Right arrow Articles by Rayner, M D

Holding potential affects the apparent voltage-sensitivity of sodium channel activation in crayfish giant axons.

P C Ruben, J G Starkus and M D Rayner

Békésy Laboratory of Neurobiology, Pacific Biomedical Research Center, University of Hawaii, Honolulu 96822.

ABSTRACT

Sodium channel activations, measured as the fraction of channels open to peak conductance for different test potentials (F[V]), shows two statistically different slopes from holding potential more positive than -90 mV. A high valence of 4-6e is indicated a test potentials within 35 mV of the apparent threshold potential (circa -65 mV at -85 mV holding potential). However, for test potentials positive to -30 mV, the F(V) curve shows a 2e valence. The F(V) curve for crayfish axon sodium channels at these "depolarized" holding potentials thus closely resembles classic data obtained from other preparations at holding potentials between -80 and -60 mV. In contrast, at holding potentials more negative than -100 mV, the high slope essentially disappears and the F(V) curve follows a single Boltzmann distribution with a valence of approximately 2e at all potentials. Neither the slope of this simple distribution nor its midpoint (-20 mV) was significantly affected by removal of fast inactivation with pronase. The change in F(V) slope, when holding potential is increased from -85 to -120 mV, does not appear to be caused by the contribution of a second channel type. The simple voltage dependence of sodium current found at Vh -120 mV be used by to discriminate between models of sodium channel activation, and rules out models with three particles of equal valence.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1990 by the Biophysical Society.