Ultraviolet photoalteration of ion channels in voltage-clamped lobster giant axons

G. S. Oxford, J. P. Pooler

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

An analysis of the ultraviolet light-induced changes in ionic conductances of lobster giant axon membranes has been carried out using the double sucrose gap voltage-clamp technique. The predominant effect of monochromatic light from a xenon arc source in the 255 to 305 nm region is an irreversible reduction in the magnitude of sodium conductance, without change in sodium channel activation or inactivation kinetics. A considerably smaller reduction in the magnitude of potassium conductance occurs, with some slowing of potassium channel activation kinetics. Leakage conductance is essentially not altered. The fall in sodium conductance follows an exponential time course toward a zero asymptote. The rate constant for conductance decrease was used as an assay for the wavelength dependence. The sodium conductance was maximally sensitive at 290 nm. It is suggested that individual sodium channels are closed upon absorption of single photons by aromatic amino acid residues in membrane proteins.

Original languageEnglish (US)
Pages (from-to)13-30
Number of pages18
JournalJournal of Membrane Biology
Volume20
Issue number1
DOIs
StatePublished - Dec 1975
Externally publishedYes

Fingerprint

Ion Channels
Axons
Sodium Channels
Sodium
Aromatic Amino Acids
Xenon
Potassium Channels
Patch-Clamp Techniques
Ultraviolet Rays
Photons
Sucrose
Potassium
Membrane Proteins
Light
Membranes

ASJC Scopus subject areas

  • Physiology
  • Cell Biology
  • Biophysics

Cite this

Ultraviolet photoalteration of ion channels in voltage-clamped lobster giant axons. / Oxford, G. S.; Pooler, J. P.

In: Journal of Membrane Biology, Vol. 20, No. 1, 12.1975, p. 13-30.

Research output: Contribution to journalArticle

Oxford, G. S. ; Pooler, J. P. / Ultraviolet photoalteration of ion channels in voltage-clamped lobster giant axons. In: Journal of Membrane Biology. 1975 ; Vol. 20, No. 1. pp. 13-30.
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