Comparison of the effects of Anemonia toxin II on sodium and gating currents in frog myelinated nerve.
Na+ and gating currents were measured in myelinated frog nerve fibres without and in the presence of 7 microM Anemonia toxin II in the extracellular solution. From the experiments, kinetic parameters of Na+ currents and of gating charge displacements during ('on' response) and after ('off' response) depolarizations were determined. The following parallel modifications of Na+ currents and charge displacements by Anemonia toxin II were observed: the toxin reduces the maximum Na+ permeability and the 'on' charge displacement; Na+ activation and 'on' charge displacement become faster; Na+ inactivation and the decline of the 'off' charge displacement with increasing pulse duration (charge immobilization) are prolonged; slow components of 'on' charge displacements are diminished. The observations support the notion that the fast 'on' charge displacement is connected with the process of Na+ activation, while Na+ inactivation is linked to charge immobilization. Our experiments suggest that slow 'on' charge displacements during longer depolarizations are correlated with the process of Na+ inactivation.
Neumcke
B
B
Schwarz
W
W
Stämpfli
R
R
D000818:Animals; D003064:Cnidarian Venoms / Q000494:pharmacology*; D004553:Electric Conductivity; D004594:Electrophysiology; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D008433:Mathematics; D009413:Nerve Fibers, Myelinated / Q000378:metabolism*; D010539:Permeability; D011893:Rana esculenta; D011901:Ranvier's Nodes / Q000502:physiology; D012964:Sodium / Q000378:metabolism*
D003064:Cnidarian Venoms; D007473:Ion Channels; C028800:toxin II (Anemonia sulcata); D012964:Sodium