Morrill G A, Ziegler D, Zabrenetzky V S
J Cell Sci. 1977 Aug;26:311-22. doi: 10.1242/jcs.26.1.311.
The uptake and efflux of 22Na and 42K 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. 22Na uptake and efflux in follicles exhibited two-step kinetics with a smaller rapidly exchanging fraction (12--15%, t0-5 approximately 15 min), and a larger slow fraction (t0-5 approximately 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.
在完全成熟、处于前期阻滞的豹蛙卵泡和去膜卵母细胞中研究了(^{22}Na)和(^{42}K)的摄取与流出。卵泡和去膜卵母细胞都含有大量的这两种阳离子，尽管在所研究的12小时内，总钠离子池的15% - 30%以及总钾离子池的1% - 2%发生了交换。卵泡中(^{22}Na)的摄取和流出呈现两步动力学，具有较小的快速交换部分（12% - 15%，(t_{0 - 5})约为15分钟）和较大的缓慢部分（(t_{0 - 5})约为0.5天）。去膜卵母细胞表现出单一的动力学部分，其速率常数与卵泡的缓慢部分相似，这表明快速部分与卵泡上皮有关。卵泡和去膜卵母细胞都表现出快速和缓慢的(^{42}K)摄取动力学部分，尽管卵泡的快速部分要大得多。相反，虽然卵泡中(^{42}K)的流出也呈现两步动力学，但去膜卵母细胞中(^{42}K)的流出呈现为单一的缓慢部分。因此，卵泡摄取的快速钾离子部分的很大一部分归因于卵泡包膜的体细胞。使用阳离子选择性微电极测量原位（卵泡内）卵母细胞细胞质中的钠和钾活性。在校正与卵泡包膜相关的钠和钾后，卵质中总钠离子的约6%以及钾离子的不到1%可被解释为结合或隔离的。
