Some electrophysiological and permeability properties of the mouse egg

R. Douglas Powers, Joseph T. Tupper

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Certain electrophysiological and ionic properties of the mouse egg (CF-1 and BDF 12-18 hr post ovulation) have been investigated. Membrane potential (-14 ± 0.4 mV, ± SE, inside negative), membrane resistance (2610 ± 38 ohm·cm2), and membrane capacitance (1.6 ± 0.03 μF cm-2) have been determined by means of intracellular microelectrode recording techniques. Membrane potential and related parameters are stable for extended periods of time upon impalement and the magnitude of the cell membrane potential has been demonstrated to be sensitive to alteration in external sodium. The electrophysiological studies in conjunction with measurements of unidirectional potassium fluxes using isotope tracer-techniques have allowed determination of membrane permeability to potassium (8 × 10-8 cm sec-1) and membrane potassium conductance (25 μmho cm-2). Furthermore, the use of tracer flux techniques has indicated that the exchangeable fraction of intracellular potassium is 204 ± 14 mM. This represents the bulk of egg potassium (222 ± 19 mM as determined from flame photometry). Studies of unidirectional potassium efflux have indicated that its movement out of the egg is made up of at least two components; an external potassium-independent potassium efflux and external potassium-dependent efflux, the latter possibly representing a potassium exchange mechanism. The combined electrophysiological and tracer-flux data indicate that only a small portion of the total membrane conductance is composed of potassium conductance at this stage of development. This and the fact that the membrane potential is far from the potassium equilibrium potential are similar to observations made on mature eggs of several other species.

Original languageEnglish (US)
Pages (from-to)320-331
Number of pages12
JournalDevelopmental Biology
Volume38
Issue number2
DOIs
StatePublished - Jun 1974

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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