TABLE 1

Potencies of suramin analogs at recombinant P2X receptors The Cheng-Prusoff equation (eq. 3) was used to calculate Ki values from the IC50 values determined in this study for NF110, NF448, MK3 (Figs. 2, 4, and 5) and the published IC50 values for NF449 (Rettinger et al., 2005). Also used in the calculation were the following EC50 values obtained for the various P2X receptor subtypes in this laboratory: 0.68 μM ATP (rP2X1), 19.9 μM ATP (rP2X2), 0.67 μM ATP (rP2X3), 17.6 μM ATP (rP2X2-X3), and 1.7 μM α,β-meATP (rP2X2+3). A competitive antagonism is supported by a Schild plot analysis (Fig. 4E). n indicates the number of independent experiments.

Receptor NF110 (para-Embedded Image) NF448 (meta-Embedded Image) MK3 (ortho-Embedded Image) NF449 (para-, ortho-Embedded Image)
Ki Normalized KianKi Normalized KibnKi Normalized KicnKi Normalized Kid
nM nM nM nM
rP2X1 82 ± 17 2.3 5 74 ± 18 1 5 26 ± 6 1 5 0.11 ± 0.01 1
rP2X2 4144 ± 613 115 6 4070 ± 526 55 4 1469 ± 247 57 5 ∼19,024 >250,000
rP2X3 36 ± 7 1 6 733 ± 164 10 6 166 ± 29 6 6 737 ± 81 6609
rP2X2-X3 35 ± 8 1 5 N.D. N.D. N.D.
rP2X2+3 35 ± 7 1 6 N.D. N.D. 76 ± 6 691

  • N.D., not determined

  • ↵ a Normalized to Ki value of NF110 of 36 nM for the rP2X3 receptor

  • ↵ b Normalized to Ki value of NF448 of 74 nM for the rP2X1 receptor

  • ↵ c Normalized to Ki value of MK3 of 26 nM for the rP2X1 receptor

  • ↵ d Normalized to Ki value of NF449 of 0.11 nM for the rP2X1 receptor