Raditsch M, Witzemann V
Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany.
FEBS Lett. 1994 Nov 7;354(2):177-82. doi: 10.1016/0014-5793(94)01118-4.
The electrophysiological analysis of Ca(2+)-conducting ion channels in Xenopus oocytes is difficult due to secondary intracellular effects induced by Ca2+. In the presence of polyvinylpyrrolidone (PVP) membrane currents can be recorded in nominally divalent cation-free solutions. The Ca(2+)-permeable recombinant NMDA receptors of the NR1/NR2A subtype were used as assay system and the results show that PVP has no effect on NMDA receptor-induced currents. Ca2+ and Ba2+ depress NMDA-induced currents at submillimolar concentrations probably by interfering with the Na+/K+ flux. This block is fully reversible as also observed for Mg2+ but shows in contrast no pronounced voltage dependence. PVP-containing solutions may be useful for the analysis of divalent cation-dependent ion channels.
由于Ca2+会引发继发性细胞内效应，因此对非洲爪蟾卵母细胞中Ca(2+)传导离子通道进行电生理分析颇具难度。在聚乙烯吡咯烷酮（PVP）存在的情况下，可在名义上无二价阳离子的溶液中记录膜电流。以NR1/NR2A亚型的Ca(2+)通透重组NMDA受体作为检测系统，结果表明PVP对NMDA受体诱导的电流无影响。Ca2+和Ba2+在亚毫摩尔浓度下可能通过干扰Na+/K+通量来抑制NMDA诱导的电流。这种阻断作用与Mg2+一样完全可逆，但与之相反的是，它没有明显的电压依赖性。含PVP的溶液可能有助于分析二价阳离子依赖性离子通道。
