Factors affecting the distribution of sodium and potassium in amphibian oocytes

Abstract

The concentrations of sodium, potassium and chloride in the nucleus and cytoplasm of amphibian oocytes were measured by electron microprobe X-ray analysis. It was confirmed that sequestered sodium, which is not or only slowly exchanged with external lithium, lies entirely in the cytoplasm, in either the cytoplasmic vesicles or yolk platelets, most probably in the vesicles. This vesicular sodium may be involved in cellular transport of sodium. Potassium is most concentrated in the nucleus and is retained by a mechanism not dependent on the sodium-potassium exchange pump, most probably by binding to protein.