Table 2.
H+ modulation of agonist potency at recombinant P2Y receptors
| rP2Y4 | rP2Y2 | |||
|---|---|---|---|---|
| EC50 (μM) | nH | EC50 (μM) | nH | |
| ATP | ||||
| pH 8.0 | 1.33±0.47 | 1.2±0.2 | 5.80±0.63 | 1.2±0.2 |
| pH 7.5 | 1.46±0.82 | 1.0±0.2 | 2.51±0.93 | 1.1±0.3 |
| pH 6.5 | 0.53±0.09 | 1.0±0.2 | 4.57±0.60 | 1.0±0.3 |
| pH 5.5 | 0.15±0.13 | 1.3±0.3 | 5.96±0.73 | 1.1±0.3 |
| UTP | ||||
| pH 7.5 | 1.79±0.92 | 1.3±0.3 | 3.63±0.28 | 0.9±0.3 |
| pH 5.5 | 0.23±0.08 | 0.9±0.1 | 3.04±0.49 | 1.1±0.3 |
Potency indices (EC50) and Hill coefficients (nH) for ATP/UTP activation of rP2Y4 receptors (left) and rP2Y2 receptors (right) expressed in Xenopus oocytes and examined under different levels of extracellular pH (pH 8.0−5.5). Data are expressed as mean±s.e.m. (n=3−6).