Comparison of the gramicidin a potassium/sodium permeability and single channel conductance ratio

E. Radford Decker, David G. Levitt

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

If the ion concentration is low enough that most channels are unoccupied, then the 'independence relations' should be satisfied and the permeability ratio should equal the conductance ratio. It has been previously reported that for the gramicidin A channel these ratios for Na+ and K+ were not equal at concentrations as low as 10 mM. However, these ratios were not measured at the same applied potential, as is required by the theory. Instead, the conductance ratio was measured at 100 mV and corrected using calculated current-voltage relations. In this report the comparison between permeability and conductance ratios is reexamined using data obtained at the correct potential. There is no significant difference in the ratios at 10 mM when they are measured at the same voltage. This implies that most channels are not occupied by sodium or potassium ions at 10 mM.

Original languageEnglish (US)
Pages (from-to)178-180
Number of pages3
JournalBBA - Biomembranes
Volume730
Issue number1
DOIs
StatePublished - Apr 21 1983

Bibliographical note

Funding Information:
This work was supported in part by a grant from the National Institutes of Health (GM25938).

Keywords

  • (Model membrane)
  • Gramicidin A
  • Ion channel
  • Single channel conductance

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