<abstract xmlns="http://www.w3.org/1999/xhtml"> The 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. The 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. These 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. These observations also indicate that Cd2+ is more eff ective than Mn2+ in blocking ion fl ow through these channels and that suppressing Ca2+-activated K+ outward currents can prolong the action potential in nerve cells. </abstract>

The 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. The 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. These 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. These observations also indicate that Cd2+ is more eff ective than Mn2+ in blocking ion fl ow through these channels and that suppressing Ca2+-activated K+ outward currents can prolong the action potential in nerve cells.

Effects of Divalent Cations on Outward Potassium Currents in Leech Retzius Nerve Cells

Faculty of Medical Science, University of Kragujevac, Svetozara Markovica 69, 34 000 Kragujevac,

Department of Pathological Physiology, Faculty of Medical Sciences, University of Kragujevac,

Experimental and Applied Biomedical Research (EABR)

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

The present study examines the effects of divalent metals, cadmium (Cd2+) and manganese (Mn2+), on the outward potassium currents of Retzius cells in the...

Effects of Divalent Cations on Outward Potassium Currents in Leech Retzius Nerve Cells

Publié en ligne: 13 déc. 2016

Pages: 309 - 314

Reçu: 22 mars 2016

Accepté: 07 avr. 2016

DOI: https://doi.org/10.1515/sjecr-2016-0029

© 2016

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.