Covariance of ion flux measurements allows new interpretation of Xenopus laevis oocyte physiology

J Exp Zool. 2001 Nov 1;290(6):652-61. doi: 10.1002/jez.1116.


An animal-vegetal net ionic current identified previously using voltage probe techniques in maturing Xenopus laevis oocytes has now been investigated using noninvasive ion-selective microelectrodes. Three-dimensional fluxes of hydrogen (H(+)), potassium (K(+)), and bicarbonate (HCO(3)(-)) were characterized with respect to the developmental stage and hemisphere of the oocyte and presence of surrounding follicular tissue. Variable effluxes of H(+) and HCO(3)(-) were recorded from both the animal and vegetal hemispheres. Variable influxes and effluxes of K(+) were also observed. The equatorial region, silent by voltage probe, exhibited fluxes of H(+) and K(+). Simultaneous measurement of pairs of ions allowed correlation analysis of two ion types. Notably for H(+) and K(+) data, positive and negative correlation at animal and vegetal poles respectively offer an explanation of the unpredictable results obtained when individual ions were observed independently.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bicarbonates / pharmacokinetics*
  • Electrophysiology
  • Embryo, Nonmammalian / physiology
  • Female
  • Ion Channels / physiology*
  • Oocytes / physiology*
  • Potassium / chemistry
  • Potassium / pharmacokinetics*
  • Protons
  • Xenopus laevis / embryology
  • Xenopus laevis / physiology*


  • Bicarbonates
  • Ion Channels
  • Protons
  • Potassium