Table 2.
(a) Effect of complete substitution of sodium by choline or NMDG on the potency (pIC50, IC50) of 5-HT in inhibiting the binding of [3H]GR65630 to intact N1E-115 cells and (b) displacement of [3H]GR65630 by 5-HT under sodium buffer condition using membranes from N1E-115 cells
| Sodium substituent | Site 1 (%) | site 2 (%) |
|---|---|---|
| pIC50±s.e.m | pIC50±s.e.m | |
| (mean IC50; μM) | (mean IC50; μM) | |
| (a) | ||
| Sodium | [52.5%] | [47.5%] |
| 6.06±0.14 | 2.94±0.06 | |
| (0.87) | (115) | |
| Choline | [32.5%] | [67.5%] |
| 4.51±0.47 | 2.90±0.17 | |
| (30.9) | (126) | |
| NMDG | [49.7%] | [50.3%] |
| 5.86±0.14 | 2.93±0.03 | |
| (1.38) | (117) | |
| (b) | ||
| Sodium | [73.3%] | [26.7%] |
| 6.80±0.14 | 2.58±0.02 | |
| (0.16) | (263) | |
Specific binding was defined as binding sensitive to inhibition by 10 mM 5-HT. From the biphasic displacement curves (shown, for example, for sodium and choline buffer in Figure 5) two binding components, a high affinity (site 1) and a low-affinity (site 2), could be calculated. Shown are means (±s.e.m.) of the pIC50 values of n=4 experiments.