The distribution of sodium, potassium and chloride in the nucleus and cytoplasm of Bufo bufo oocytes measured by electron microprobe analysis.

Elemental content in the nucleus and in yolk and yolk‐free cytoplasm of developing Rana pipiens oocytes: An X‐ray microanalysis study

“…Our nuclearlyolk-free cytoplasmic Na ration is 0.92, as compared to 3.19 reported by Naoraet al by Dick (1978). Our K content ratios compare favorably with the "concentration" ratios of the above mentioned authors since the unit of water measurement they use does not differentiate between free and ordered water.…”

Factors affecting the distribution of sodium and potassium in amphibian oocytes

“…The high C/N ratio is probably due to the fact that most (if not all) the nuclear Na exchanges with external Li, while only half the cytoplasmic Na exchanges with external Li. The C/N ratio obtained in the present experiments is higher than most of those obtained in previous studies on Li-exposed amphibian oocytes, which vary from 2.2 to 14.3, but confirms previous studies which indicated the presence of an internal cytoplasmic fraction of Na in the oocyte which is inexchangeable (or very slowly exchangeable) with external Li (7,9,10,12,14).…”

“…Although some older studies showed nuclear Na higher than cytoplasmic (l, 22), more recent studies have shown the nuclear Na concentration to be roughly equal to (7,10) or less than (5,24) the cytoplasmic Na concentration. On the other hand the nuclear K concentration has been reported to be much higher than the cytoplasmic (7).…”

“…Although some older studies showed nuclear Na higher than cytoplasmic (l, 22), more recent studies have shown the nuclear Na concentration to be roughly equal to (7,10) or less than (5,24) the cytoplasmic Na concentration. On the other hand the nuclear K concentration has been reported to be much higher than the cytoplasmic (7). The purpose of the present studies was to provide further evidence in relation to the distribution of nuclear and cytoplasmic Na and K and any subfractions of them, and also to attempt to determine the factors governing their distribution.…”

Sodium entry through endothelial store-operated calcium entry channels: regulation by Orai1

“…Intracellular estimates suggest that cytosolic sodium concentrations are ϳ5 mM, although concentrations approaching 12 mM have been reported (23,34,47,48). It appears that sodium concentrations vary among intracellular compartments; for example, endoplasmic reticulum, mitochondrial, and nuclear concentrations have been estimated to be ϳ27, 10 -50, and 108 mM (or higher), respectively (3,8,19,27,35). From these estimates, it appears that a sodium concentration gradient exists between the luminal contents of organelles and the cytosol.…”