Photodynamic alteration of lobster giant axons in calcium-free and calcium-rich media

John Pooler, Gerry S. Oxford

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Photodynamic alteration of Eosin Y-sensitized lobster giant axons was compared under conditions of calcium-rich and calcium-free media, to see whether the conflicting reported descriptions of the photodynamic effect can be resolved in terms of variations in calcium content of the bathing medium. Both a voltage clamp analysis (sucrose gap technique) and a microelectrode analysis (nonclamped axons) were used. In calcium-free media the characteristic photodynamic alterations of sodium channels (reduction in maximum conductance; increase in time to peak current) occurred at 40% slower rates than in calcium-rich media, while the characteristic decrease in potassium current was unaffected by the calcium content. Photodynamic alteration depolarized nonvoltage clamped axons in both media, and there was an initial rapid depolarization phase in calcium-free media. All of these changes in both media were irreversible. In calcium-free media photodynamic alteration usually induced repetitive firing. The firing showed apparent reversibility, since it stopped after a period of time and could usually be reinitiated upon further illumination. It is proposed that decalcification does not alter the basic nature of the photodynamic effect, but complicates the axon response by its own independent effects.

Original languageEnglish (US)
Pages (from-to)339-348
Number of pages10
JournalJournal of Membrane Biology
Volume12
Issue number1
DOIs
StatePublished - Dec 1973
Externally publishedYes

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Axons
Calcium
Sodium Channels
Microelectrodes
Eosine Yellowish-(YS)
Lighting
Sucrose
Potassium

ASJC Scopus subject areas

  • Physiology
  • Cell Biology
  • Biophysics

Cite this

Photodynamic alteration of lobster giant axons in calcium-free and calcium-rich media. / Pooler, John; Oxford, Gerry S.

In: Journal of Membrane Biology, Vol. 12, No. 1, 12.1973, p. 339-348.

Research output: Contribution to journalArticle

Pooler, John ; Oxford, Gerry S. / Photodynamic alteration of lobster giant axons in calcium-free and calcium-rich media. In: Journal of Membrane Biology. 1973 ; Vol. 12, No. 1. pp. 339-348.
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