Small Conductance Ca Activated K Channels in Mollusks

  • A. Hermann
  • C. Erxleben
  • D. Armstrong

Abstract

In many cells intracellular Ca ions activate a conductance to K ions in the plasma membrane. Among the cells where this property of Ca ions was detected first were neurons from the marine mollusk, Aplysia californica (Meech, 1976). The biophysical, pharmacological and physiological properties of that K conductance have now been studied in detail in molluscan neurons. The K conductance is not only sensitive to calcium ions but also intrinsically voltage-dependent. Probing the internal Ca receptor site with different divalent cations has revealed that ions such as cadmium or strontium also activate these K channels effectively (Gorman and Hermann, 1979). Pharmacological studies further showed that the Ca activated K current is highly sensitive to block by external tetraethylammonium (TEA) and that other types of K currents in these cells are not equally sensitive to TEA or 4-aminopyridine (4-AP) (Hermann and Gorman, 1981a, b; Hermann and Hartung, 1986). The physiological properties attributed to the Ca dependent conductance include a contribution to the repolarization and after-hyperpolarization of action potentials, post-tetanic hyperpolarization, frequency adaptation, and the termination of bursting pacemaker potentials (Meech, 1978; Hermann and Hartung, 1983).

Keywords

Permeability Cadmium Serotonin Polypeptide Strontium 

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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • A. Hermann
    • 1
  • C. Erxleben
    • 2
  • D. Armstrong
    • 3
  1. 1.Institute of ZoologyUniversity of SalzburgSalzburgAustria
  2. 2.Faculty of BiologyUniversity of KonstanzKonstanzGermany
  3. 3.Department of BiologyUniversity of CaliforniaLos AngelesUSA

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