Dierkes Paul Wilhelm, Wüsten Hans Joachim, Klees Guido, Müller Anja, Hochstrate Peter
Institut für Neurobiologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany.
Pflugers Arch. 2006 Apr;452(1):25-35. doi: 10.1007/s00424-005-0009-6. Epub 2005 Dec 10.
By using electrophysiological and microfluorimetric methods, we found that leech Retzius neurons swell after inhibition of the Na(+)-K(+) pump by the cardiac glycoside ouabain. To explore the mechanism of this swelling, we measured the effect of ouabain on Na(+), K(+), and Cl(-), as well as on the membrane potential, by applying triple-barrelled ion-sensitive microelectrodes. As shown previously, ouabain induced a marked Na(+) increase, a K(+) decrease, and a membrane depolarization, and it also evoked an increase in Cl(-). The analysis of the data revealed a net uptake of NaCl, which quantitatively explained the ouabain-induced cell swelling. In the absence of extracellular Na(+) or Cl(-), NaCl uptake was excluded, and the cell volume remained unaffected. Likewise, NaCl uptake and, hence, cell swelling did not occur when the Na(+)-K(+) pump was inhibited by omitting bath K(+). Also, in K(+)-free solution, Na(+) increased and K(+) dropped, but Cl(-) slightly decreased, and after an initial, small membrane depolarization, the cells hyperpolarized for a prolonged period. It is concluded that the ouabain-induced NaCl uptake is caused by the depolarization of the plasma membrane, which augments the inwardly directed electrochemical Cl(-) gradient.
通过使用电生理和微量荧光法，我们发现，在用强心苷哇巴因抑制钠钾泵后，水蛭Retzius神经元会肿胀。为了探究这种肿胀的机制，我们通过应用三管离子敏感微电极，测量了哇巴因对细胞内钠离子（[Na⁺]i）、钾离子（[K⁺]i）和氯离子（[Cl⁻]i）的影响，以及对膜电位的影响。如先前所示，哇巴因可导致细胞内钠离子显著增加、钾离子减少以及膜去极化，并且还会引起细胞内氯离子增加。数据分析显示存在氯化钠的净摄取，这从数量上解释了哇巴因诱导的细胞肿胀。在没有细胞外钠离子或氯离子的情况下，排除了氯化钠的摄取，细胞体积保持不变。同样，当通过省略浴液中的钾离子来抑制钠钾泵时，不会发生氯化钠摄取以及细胞肿胀。此外，在无钾溶液中，细胞内钠离子增加，钾离子减少，但细胞内氯离子略有减少，并且在最初出现小幅度膜去极化后，细胞会超极化较长一段时间。结论是，哇巴因诱导的氯化钠摄取是由质膜去极化引起的，质膜去极化增强了内向的电化学氯离子梯度。
