Antagonism of h5-HT1A receptor-mediated stimulation of [35S]GTPγ S binding to Gαi3 subunits by WAY100,635
| pKBValues | ||||
|---|---|---|---|---|
| Ligands | Ascending Component | Descending Component | n | |
| Constant [Antagonist] | ||||
| 5-HT + WAY (10 nM) | 9.68 ± 0.10 | 9.74 ± 0.10 | 8 | |
| (+)-8-OH-DPAT + WAY (10 nM) | 9.23 ± 0.09 | 9.66 ± 0.12 | 3 | |
| Pindolol + WAY (3 nM) | 9.19 ± 0.19 | 4 | ||
| Spiperone + WAY (3 nM) | 9.58 ± 0.27 | 4 | ||
| Constant [Agonist] | ||||
| Pindolol (100 nM) + WAY | 9.46 ± 0.04 | 3 | ||
| Spiperone (1 μM) + WAY | - | 9.63 ± 0.11 | 3 | |
Activation of Gα i3 G-protein subunits in CHO-h5-HT1A cell membranes was determined employing an antibody-capture/SPA detection technique. Ligands were preincubated with membranes for 30 min before adding [35S]GTPγ S. Fixed concentrations (3 or 10 nM) of WAY100,635 shifted the isotherms of 5-HT, (+)-8-OH-DPAT, pindolol, and spiperone. For 5-HT and (+)8-OH-DPAT, pK B values were calculated for the ascending and descending components of bell-shaped isotherms. Stimulation induced by pindolol (100 nM) and inhibition induced by spiperone (1 μM) were concentration-dependently reversed by WAY100,635. pK B values resemble the pK i value (9.91) of WAY100,635 at h5-HT1A receptors (Newman-Tancredi et al., 2001a). Data are expressed as mean ± S.E.M. of n independent determinations performed in duplicate.