Gögelein H, Van Driessche W
J Membr Biol. 1981;63(3):243-54. doi: 10.1007/BF01870985.
Current noise power spectra of the voltage-channel (V = 0) Necturus gallbladder, exposed to NaCl-Ringer's on both sides contained a relaxation noise component, which overlapped with a 1/f alpha noise component, with alpha being about 2. Substitution of all Na+ by K+ on either the serosal or mucosal side increased the relaxation as well as the 1/f alpha noise component considerably. In Necturus gallbladder both noise components are reduced by addition of 10 mM, 2,4,6-triaminopyrimidine (TAP) or 5 mM BA2+ to the mucosal side, as well as by acidification of the mucosal solution to pH 5 and lower. Five mM of tetraethylammonium (TEA+) added to the mucosal solution, abolished K+ relaxation noise and decreased the 1/f alpha noise component. Applying a Cs+ concentration gradient across the epithelium did not yield relaxation noise. However, if Rb+ was substituted for all Na+ on one side, a Lorentzian noise component appeared in the spectrum. Its plateau was smaller than with KCl-Ringer's on the respective side. These data confirm the existence of fluctuating K+ channels in the apical membrane of the Necturus gallbladder. Furthermore it can be concluded that these channels have the permeability sequence K+ greater than Rb+ greater than Cs+. The inhibition of the fluctuations by mucosal acidification indicates the existence of acidic sites in the channel. The single-channel conductance was estimated to be between 6.5 and 40 pS.
两侧均暴露于氯化钠林格液中的美洲大鲵胆囊电压通道（V = 0）的电流噪声功率谱包含一个弛豫噪声成分，它与一个α约为2的1/fα噪声成分重叠。在浆膜侧或黏膜侧用K⁺完全替代所有Na⁺会显著增加弛豫以及1/fα噪声成分。在美洲大鲵胆囊中，向黏膜侧添加10 mM 2,4,6 - 三氨基嘧啶（TAP）或5 mM Ba²⁺，以及将黏膜溶液酸化至pH 5及更低，都会使这两种噪声成分降低。向黏膜溶液中添加5 mM四乙铵（TEA⁺）可消除K⁺弛豫噪声并降低1/fα噪声成分。在整个上皮细胞上施加Cs⁺浓度梯度不会产生弛豫噪声。然而，如果在一侧用Rb⁺完全替代所有Na⁺，则光谱中会出现一个洛伦兹噪声成分。其平台比相应侧使用氯化钾林格液时小。这些数据证实了美洲大鲵胆囊顶端膜中存在波动的K⁺通道。此外，可以得出结论，这些通道的通透性顺序为K⁺＞Rb⁺＞Cs⁺。黏膜酸化对波动的抑制表明通道中存在酸性位点。单通道电导估计在6.5至40 pS之间。
