An analysis of transport, exchange, and binding of sodium and potassium in isolated amphibian follicles and denuded oocytes
Open Access
- 1 August 1977
- journal article
- research article
- Published by The Company of Biologists in Journal of Cell Science
- Vol. 26 (1), 311-322
- https://doi.org/10.1242/jcs.26.1.311
Abstract
The uptake and efflux of 22Na and 42,K were studied in fully grown, prophase-arrested Rana pipiens follicles and denuded oocytes. Follicles and denuded oocytes contained large stores of both cations, although only 15–30% of the total Na+ and 1–2% of the total K+ pools exchanged within the 12-h period studied. “Na uptake and efflux in follicles exhibited two-step kinetics with a smaller rapidly exchanging fraction (12–15%, t0·5 ∼ 15 min), and a larger slow fraction (t0·5. ∼ 0·5 day). Denuded oocytes displayed a single kinetic fraction with a rate constant similar to the slow fraction of follicles, suggesting that the fast fraction was associated with the follicular epithelium. Both follicles and denuded oocytes exhibited fast and slow 42K uptake kinetic fractions, although the follicular fast fraction was considerably larger. Conversely, whereas follicular 42K efflux also proceeded with two-step kinetics, 42K efflux from denuded oocytes appeared as a single slow fraction. Thus, a large portion of the fast K+ fraction taken up by the follicles is attributable to the somatic cells of the follicular envelopes. Na+ and K+ activities were measured in the cytoplasm of the in situ (follicular) oocyte using cation-selective microelectrodes. After correcting for Na+ and K+ associated with the follicular envelopes, only about 6% of the total ooplasmic Na+ and less than 1% of the K+ could be accounted for as bound or sequestered.This publication has 20 references indexed in Scilit:
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