两栖类细有髓神经纤维中的钾离子通透性。

Potassium permeability in thin amphibian myelinated fibres.

作者信息

Brismar T

出版信息

Pflugers Arch. 1982 Jun;393(4):348-50. doi: 10.1007/BF00581423.

Abstract

Potential clamp analysis of thin (10-12 micrometers) myelinated fibres from amphibia (Xenopus laevis and Rana temporaria) showed that they had a large delayed K-permeability (PK) and a PK/PNa-ratio of 0.32, which is similar to the ratio in large (25-30 micrometers) frog fibres. These results agree with earlier evidence of a large delayed PK in 10-15 micrometers Rana fibres; a recent description of a size-dependent difference in PK was thus not confirmed. The large PK (0.32 cm3s-1 X 10(-9) in 10-12 micrometers amphibian fibres contrasted with the small PK (0.05 cm3 s-1 X 10(-9) in 12 micrometers rat fibres. Frog and toad fibres also had a larger nodal capacitance (4 pF), but smaller leak conductance (18 nS) than rat fibres (1.4 pF and 29 nS). These differences may be related to the morphological evidence of a more open node with a larger surface area in the amphibian as compared to the rat node.

摘要

对来自两栖动物（非洲爪蟾和欧洲林蛙）的细（10 - 12微米）有髓纤维进行的电压钳分析表明，它们具有较大的延迟钾通透性（PK），PK/PNa比值为0.32，这与大（25 - 30微米）蛙类纤维中的比值相似。这些结果与早期关于10 - 15微米欧洲林蛙纤维中存在较大延迟PK的证据一致；因此，最近关于PK大小依赖性差异的描述未得到证实。10 - 12微米两栖动物纤维中较大的PK（0.32 cm³s⁻¹×10⁻⁹）与12微米大鼠纤维中较小的PK（0.05 cm³ s⁻¹×10⁻⁹）形成对比。青蛙和蟾蜍纤维的节电容也更大（4 pF），但漏电导比大鼠纤维（1.4 pF和29 nS）小（18 nS）。这些差异可能与形态学证据有关，即与大鼠的节相比，两栖动物的节更开放，表面积更大。