Changes in ion permeability and membrane potential during early echinoderm development: electrophysiological and tracer flux determinations

J. T. Tupper, R. D. Powers

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

After fertilization the membrane potential of the Asterias embryo undergoes an approximately fourfold increase in internal negativity, as measured by intracellular microelectrodes. Previous experiments have demonstrated that the ionic basis of the membrane potential in this embryo may be described by a simplified form of the constant field equation. Using this relationship, the present experiments illustrate that the relative permeability of Na to K [P(Na)/P(K)] may be determined at any time during the early cleavage of this embryo. The results of these experiments indicate a relative increase of PCK as related to P(Na) as the mechanism responsible for the large change in membrane potential. This has been confirmed by independent determination of absolute values for P(Na) and P(K) by means of 24Na and 42K tracer flux analysis. Experiments carried out during early cleavage demonstrate a greater than 2 fold increase in K permeability (3.8 x 10-7 cm/sec to 9.5 x 10-7 cm/sec) with no concurrent alteration in Na permeability (0.1 x 10-7 cm/sec). P(Na)/P(K) in 15 min and 2 hr post fertilized embryos is 0.03 and 0.01 respectively. Its magnitude is the same whether determined by the constant field assumption or from tracer flux analysis. These changes in ionic permeability occur on a time scale which is similar to that of increased metabolic and synthetic activities in other echinoderm embryos.

Original languageEnglish (US)
Pages (from-to)353-364
Number of pages12
JournalJournal of Experimental Zoology
Volume184
Issue number3
StatePublished - 1973

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Echinodermata
membrane potential
tracer techniques
permeability
embryo (animal)
ions
Asterias

ASJC Scopus subject areas

  • Animal Science and Zoology

Cite this

Changes in ion permeability and membrane potential during early echinoderm development : electrophysiological and tracer flux determinations. / Tupper, J. T.; Powers, R. D.

In: Journal of Experimental Zoology, Vol. 184, No. 3, 1973, p. 353-364.

Research output: Contribution to journalArticle

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