Characterization of Ca2+ flows essential in ornithine decarboxylase induction by L-asparagine in rat hepatoma cells using Ca2+ flow inhibitors

Patrick C.L. Wong*, Kwok Po Hau, Henry H.N. Pong, Platini P.F. Kwok, David W F FONG

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

L-Asparagine stimulates bi-directional Ca2+ flows and induces ornithine decarboxylase in Reuber H-35 hepatoma cells. Previously it has been shown that these effects are completely, but reversibly inhibited by lanthanum chloride. In this study we examined the role(s) of Ca2+ flows using more specific Ca2+ flow inhibitors. It was shown that ornithine decarboxylase induction was inhibited by CdCl2, and verapamil at concentrations above 1 μM and 100 μM respectively, but was unaffected by as much as 300 μM NiCl2, 1 mM nifedipine, or 10 μM ω-conotoxin. Enzyme induction was blocked by the Ca2+-ATPase pump antagonists vanadate and Compound 48/80 in a dose-dependent manner. These results, taken together with the observations that extracellular Ca2+ is essential for enzyme induction but a substantial elevation of cytoplasmic [Ca2+] is not, suggest that Ca2+ inflow independent of the receptor-activated Ca2+ channels, and the Ca2+ ATPase mediated Ca2+ out-flow, are both important factors in the action of L-asparagine.

Original languageEnglish
Pages (from-to)1041-1047
Number of pages7
JournalBiochemistry and Molecular Biology International
Volume38
Issue number5
Publication statusPublished - 1996

Scopus Subject Areas

  • Biochemistry
  • Molecular Biology
  • Genetics

User-Defined Keywords

  • ω-conotoxin
  • Ca
  • Cd
  • Compound 40/80
  • H-35 cells
  • L-asparagine
  • Ni
  • Nifedipine
  • Ornithine decarboxylase
  • Vanadate
  • Verapamil

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