Covariance of ion flux measurements allows new interpretation of Xenopus laevis oocyte physiology.
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.
Faszewski
E E
EE
Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003-5810, USA. efaszewski@wheelock.edu
Kunkel
J G
JG
D000818:Animals; D001639:Bicarbonates / Q000493:pharmacokinetics*; D004594:Electrophysiology; D004625:Embryo, Nonmammalian / Q000502:physiology; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D009865:Oocytes / Q000502:physiology*; D011188:Potassium / Q000737:chemistry / Q000493:pharmacokinetics*; D011522:Protons; D014982:Xenopus laevis / Q000196:embryology / Q000502:physiology*
D001639:Bicarbonates; D007473:Ion Channels; D011522:Protons; D011188:Potassium