The Journal of Membrane Biology

, Volume 102, Issue 2, pp 97–104

Cadmium inhibits plasma membrane calcium transport

  • P. M. Verbost
  • G. Flik
  • R. A. C. Lock
  • S. E. Wendelaar Bonga
Articles

DOI: 10.1007/BF01870448

Cite this article as:
Verbost, P.M., Flik, G., Lock, R.A.C. et al. J. Membrain Biol. (1988) 102: 97. doi:10.1007/BF01870448

Summary

The interaction of Cd2+ with the plasma membrane Ca2+-transporting ATPase of fish gills was studied. ATP-driven Ca2+-transport in basolateral membrane (BLM) vesicles was inhibited by Cd2+ with anI50 value of 3.0nm at 0.25 μm free Ca2+ using EGTA, HEEDTA and NTA to buffer Ca2+ and Cd2+ concentrations. The inhibition was competitive in nature since theK0.5 value for Ca2+ increased linearly with increasing Cd2+ concentrations while theVmax remained unchanged. The Ca2+ pump appeared to be calmodulin dependent, but we conclude that the inhibition by Cd2+ occurs directly on the Ca2+ binding site of the Ca2+-transporting ATPase and not via the Ca2+-binding sites of calmodulin. It is suggested that Cd2+-induced inhibition of Ca2+-transporting enzymes is the primary effect in the Cd2+ toxicity towards cells followed by several secondary effects due to a disturbed cellular Ca2+ metabolism. Our data illustrate that apparent stimulatory effects of low concentrations of Cd2+ on Ca2+-dependent enzymes may derive from increased free-Ca2+ levels when Cd2+ supersedes Ca2+ on the ligands.

Key Words

BLM vesicles Ca2+ transport Cd2+ inhibition calmodulin trout gills 

Copyright information

© Springer-Verlag New York Inc 1988

Authors and Affiliations

  • P. M. Verbost
    • 1
  • G. Flik
    • 1
  • R. A. C. Lock
    • 1
  • S. E. Wendelaar Bonga
    • 1
  1. 1.Department of Animal Physiology, Faculty of ScienceUniversity of NijmegenNijmegenThe Netherlands

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