The Journal of Membrane Biology

, Volume 118, Issue 3, pp 243–249

Cytotoxicity of equinatoxin II from the sea anemoneActinia equina involves ion channel formation and an increase in intracellular calcium activity

  • R. Zorec
  • M. Tester
  • P. Maček
  • W. T. Mason

DOI: 10.1007/BF01868608

Cite this article as:
Zorec, R., Tester, M., Maček, P. et al. J. Membrain Biol. (1990) 118: 243. doi:10.1007/BF01868608


Equinatoxin Il is a 20-kDa basic protein isolated from the sea anemoneActinia equina. The aim of our work was to investigate the primary molecular basis for the cytotoxic effects of equinatoxin II in two model systems: single bovine lactotrophs and planar lipid bilayers. Previous work has shown that equinatoxin II produces rapid changes in cell morphology, which are dependent on external calcium. It has also been reported that addition of equinatoxin II increases membrane electrical conductance, which suggests that the cytotoxic action of equinatoxin II involves an increase in the permeability of membranes to Ca2+. Extensive changes in cytosolic Ca2+ activity are thought to invoke irreversible changes in cell physiology and morphology. In this paper, we show that morphological changes brought about by equinatoxin II in bovine lactotrophs are associated with a rapid rise in cytosolic Ca2+ activity, monitored with a fura-2 video imaging apparatus. Moreover, incorporation of equinatoxin II into planar lipid bilayers produces Ca2+ permeable ion channels. This suggests that the mode of equinatoxin II cytotoxicity involves the formation of cation (Ca2+) permeable channels in cell membranes.

Key Words

fura-2 imagingplanar lipid bilayersCa channelsbovine lactotrophsequinatoxinsea anemoneAclinia equina

Copyright information

© Springer-Verlag New York Inc 1990

Authors and Affiliations

  • R. Zorec
    • 1
  • M. Tester
    • 2
  • P. Maček
    • 3
  • W. T. Mason
    • 4
  1. 1.Institute of PathophysiologyUniversity of LjubljanaLjubljanaYugoslavia
  2. 2.Botany SchoolUniversity of CambridgeCambridgeUK
  3. 3.Department of BiologyBiotechnical FacultyLjubljanaYugoslavia
  4. 4.A.F.R.C.Institute of Animal PhysiologyCambridgeUK
  5. 5.Department of BotanyUniversity of AdelaideAdelaideAustralia