Inhibition of ecto-ATPase by the P2 purinoceptor agonists, ATPγS, α,β-methylene-ATP, and AMP-PNP, in endothelial cells

Bing Chang Chen, Wan Wan Lin

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27 Citations (Scopus)

Abstract

Ecto-ATPase is a plasma membrane-bound enzyme that sequentially dephosphorylates extracellular nucleotides such as ATP. This breakdown of ATP and other nucleotides makes it difficult to characterize and classify P2 purinoceptors. We have previously shown that the P2 purinergic antagonists, PPADS, suramin and reactive blue, act as ecto-ATPase inhibitors in various cell lines. Here, we show that the P2 purinergic agonists, ATPγS, α,β-methylene ATP ((α,β-MeATP) and AMP-PNP, inhibit the ecto-ATPase of bovine pulmonary artery endothelial cells (CPAE), with pIC50 values of 5.2, 4.5 and 4.0, respectively. In CPAE, FPL67156, a selective ecto-ATPase inhibitor, also inhibits ecto-ATPase activity, with a pIC50 value of 4.0. In addition, (α,β-MeATP (3-100 μM), which itself does not induce phosphoinositide (PI) turnover, left-shifted the agonist-concentration effect (E/[A]) curves for ATP, 2MeS-ATP and UTP by approximate 100-300 fold, while those for ATPγS and AMP-PNP were only shifted approximately 2-3 fold. Moreover, in the presence of α,β-MeATP, not only was the potentiation effect of PPADS on the UTP response lost, but a slight inhibition of the UTP response by PPADS was also seen. Thus, we conclude that the action of ATPγS, α,β-MeATP and AMP-PNP as ecto-ATPase inhibitors account for their high agonist potency, and also provide information for the development of ecto-ATPase inhibitors of high selectivity and potency.

Original languageEnglish
Pages (from-to)442-446
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume233
Issue number2
DOIs
Publication statusPublished - Apr 17 1997
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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