A Quantitative Description of Nodal Membrane Currents in Myelinated Nerve Fibres of the Lizard Anous Carolinensis

摘要: Experiments were performed on individual nodes of Ranvier from a lizard at 15–16°C, using the method Nonner (1969). In addition to leakage current (mean conductance 19.7 nS), membrane ionic currents consisted Na+ current, completely inhibited by lμmoll−1 external tetrodotoxin, and K+ sensitive tetraethylammonium ions internal caesium ions. The inactivation time course Na+current 0 mV was well fitted sum two exponential phases, one fast slow, with mean constants 0.68 2.92 ms, respectively. contrast observations amphibian mammalian preparations, peak showed an almost linear potential dependence large positive potentials. A maximum 146.8 nS calculated. Both indicated that it similar found in Ranvier. 51.9 nS. Furthermore, as described amphibians, three different components (s, f1 f2) could be separated. We conclude that, under experimental conditions, nodal are qualitatively quantitatively myelinated nerve fibres, suggesting these preparations contains types channels. These results strengthen view near absence channels is peculiarity nerves.