Effects of divalent cations on outward potassium currents in leech retzius nerve cells

Abstract

© 2016, University of Kragujevac, Faculty of Science. All rights reserved. e present study examines the effects of divalent metals, cadmium (Cd2+) and manganese (Mn2+), on the outward potassium currents of Retzius cells in the hirudinid leeches Haemopis sanguisuga using conventional two-microelectrode voltageclamp techniques. e outward potassium current is activated by depolarization and plays an important role in determining both the neuronal excitability and action potential duration. A strong inhibition of the fast current and a clear reduction in the late currents of the outward current with 1 mM Cd2+ were obtained, which indicated that both components are sensitive to this metal. Complete blockage of the fast and partial reduction of the slow outward currents was observed after adding 1 mM Mn2+ to the extracellular fluid. ese data show that the outward K+ current in leech Retzius nerve cells comprises at least two components: a voltage-dependent K+ current and a Ca2+- activated K+ current. ese observations also indicate that Cd2+ is more effective than Mn2+ in blocking ion flow through these channels and that suppressing Ca2+-activated K+ outward currents can prolong the action potential in nerve cells.