Table 1.
Pharmacological properties of P2X2, P2X2/5, and P2X5 receptors expressed in Xenopus oocytes
| ATP |
BzATP |
ATPγS |
TNP-ATP |
|||||
|---|---|---|---|---|---|---|---|---|
| EC50, μm | I/IP2X2 (100 μm) % | EC5, μm | IBzATP/IATP,a % | EC50, μm | IATPγS/IATP,b % | 1 μm,c % | 10 μm, % | |
| P2X2 | 5.3 ± 0.9 (n = 5) | 100 ± 0.06 (n = 5) | 28 ± 0.4 (n = 5) | 60.6 ± 6.9 (n = 5) | 5.9 ± 0.2 (n = 6) | 94.4 ± 4.1 (n = 6) | 96 ± 0.9 (n = 3) | 46.1 ± 6.4 (n = 11) |
| P2X2/5 | 12.6 ± 0.4** (n = 13) | 90.9 ± 3.9 (n = 13) | 82 ± 0.9*** (n = 6) | 14.1 ± 3.1*** (n = 6) | 22.3 ± 0.1*** (n = 8) | 113 ± 4.5 (n = 8) | 85.9 ± 3.14 (n = 11) | 20.8 ± 2.5** (n = 11) |
| P2X5 | 18.7 ± 2** (n = 7) | 6.7 ± 2.7*** (n = 7) | N.D. | N.D. | N.D. | N.D. | N.D. | N.D. |
In the case of P2X2/5 expression, P2X5 and P2X2 mRNAs were mixed at a 3:1 ratio to minimize the presence of homomeric P2X2 receptors. Consequently, for homomeric P2X2 expression, mRNA was diluted at the same ratio with water. P2X5 mRNA was not diluted for homomeric P2X5 expression.
**p < 0.01,
***p < 0.005, unpaired Student's t test.
a300 μm BzATP, 100 μm ATP.
b100 μm ATPγS, 30 μm ATP.
cP2X2 was activated with 10 μm ATP; P2X2/5 was activated with 30 μm ATP. Percentage of residual current in the presence of TNP-ATP.