Shetlar R E, Schölermann B, Morrison A I, Kinne R K
Max-Planck-Institut für Systemphysiologie, Dortmund, F.R.G.
Biochim Biophys Acta. 1990 Apr 13;1023(2):184-90. doi: 10.1016/0005-2736(90)90412-h.
In order to characterize the transport systems mediating K+ uptake into oocytes, flux studies employing 86Rb were performed on Xenopus oocytes stripped of follicular cells by pretreatment with Ca2(+)-Mg2(+)-free Barth's medium. Total Rb+ uptake consisted of an ouabain-sensitive and an ouabain-insensitive flux. In the presence of 100 mmol/l NaCl and 0.1 mmol/l ouabain the ouabain-insensitive flux amounted to 754.7 +/- 59.9 pmol/oocyte per h (n = 30 cells, i.e., 10 cells each from three different animals). In the absence of Na+ (Na+ substituted by N-methylglucamine) or when Cl- was replaced by NO3- the ouabain-insensitive flux was reduced to 84.4 +/- 42.9 and 79.2 +/- 12.1 pmol/oocyte per h, respectively (n = 50 cells). Furthermore, this Na(+)- and Cl(-)-dependent flux was completely inhibited by 10(-4) mol/l bumetanide, a specific inhibitor of the Na(+)-K(+)-2Cl- cotransport system. These results suggest that K+ uptake via a bumetanide-sensitive Na(+)-K(+)-2Cl- cotransport system represents a major K+ pathway in oocytes.
为了表征介导钾离子摄取进入卵母细胞的转运系统，我们对经无钙镁巴氏液预处理去除滤泡细胞的非洲爪蟾卵母细胞进行了使用⁸⁶Rb的通量研究。总的铷离子摄取包括哇巴因敏感通量和哇巴因不敏感通量。在含有100 mmol/L氯化钠和0.1 mmol/L哇巴因的情况下，哇巴因不敏感通量为每小时754.7±59.9 pmol/卵母细胞（n = 30个细胞，即来自三只不同动物的各10个细胞）。在无钠离子（用N - 甲基葡糖胺替代钠离子）或氯离子被硝酸根替代时，哇巴因不敏感通量分别降至每小时84.4±42.9和79.2±12.1 pmol/卵母细胞（n = 50个细胞）。此外，这种依赖钠离子和氯离子的通量被10⁻⁴ mol/L布美他尼完全抑制，布美他尼是钠 - 钾 - 2氯离子协同转运系统的特异性抑制剂。这些结果表明，通过布美他尼敏感的钠 - 钾 - 2氯离子协同转运系统摄取钾离子是卵母细胞中主要的钾离子摄取途径。
