Trinitrophenyl-Substituted Nucleotides Are Potent Antagonists Selective for P2X1, P2X3, and Heteromeric P2X2/3 Receptors
- 1Geneva Biomedical Research Institute, Glaxo Wellcome Research and Development, Geneva, 1228 Switzerland (C.V., A.S., R.A.N.) and2Exploratory Chemistry, Glaxo Wellcome Research and Development, Stevenage, SG1 2NY, United Kingdom (G.R.)
Abstract
There are currently seven P2X receptor subunits (P2X1–7) defined by molecular cloning. The functional identification of these receptors has relied primarily on the potency of α,β-methylene-ATP relative to that of ATP and on the kinetics of receptor desensitization. In the present experiments we found that the 2′,3′-O-(2,4,6-trinitrophenyl)-substituted analogs of ATP are selective and potent antagonists at some but not all P2X receptors. The trinitrophenyl analogs of ATP, ADP, AMP, and GTP produced a reversible inhibition of ATP-evoked currents in human embryonic kidney 293 cells expressing P2X1 receptors, P2X3 receptors, or both P2X2 and P2X3 (heteromeric) receptors; IC50 values were close to 1 nm. These compounds were at least 1000-fold less effective in blocking currents in cells expressing P2X2, P2X4, or P2X7receptors (P2X5 and P2X6 not tested). GTP, 2,4,6-trinitrophenol, and the 2′,3′-trinitrophenyl analog of adenosine (0.1–10 μm) had no effect. Thus, we have identified a structural motif that confers antagonist action at P2X receptors that contain P2X1 or P2X3 subunits (the α,β-methylene-ATP-sensitive subclass).
Footnotes
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Send reprint requests to: Dr. R. A. North, Institute of Molecular Pharmacology, Department of Biomedical Sciences, University of Sheffield, Alfred Denny Building, Sheffield SIO 2TN, England, UK. E-mail: r.a.north{at}sheffield.ac.uk
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↵1 Current affiliation: Department of Pharmacology, Glaxo Wellcome Research and Development, 37135 Verona, Italy
- Abbreviations:
- αβmeATP
- α,β-methylene-ATP
- HEK
- human embryonic kidney
- HEPES
- 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- PPADS
- pyridoxal 5-phosphate 6-azophenyl-2′,4′-disulphonic acid
- TNP
- trinitrophenyl
- TNP-A
- 2′,3′-O-(2,4,6-trinitrophenyl)-adenosine
- TNP-ADP
- 2′,3′-O-(2,4,6-trinitrophenyl)-ADP
- TNP-AMP
- 2′,3′-O-(2,4,6-trinitrophenyl)-AMP
- TNP-ATP
- 2′,3′-O-(2,4,6-trinitrophenyl)-ATP
- TNP-GTP
- 2′,3′-O-(2,4,6-trinitrophenyl)-GTP
- EGTA
- ethylene glycol bis(β-aminoethyl ether)-N,N,N′,N′,-tetraacetic acid
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- Received January 12, 1998.
- Accepted February 18, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
