Effect of NaCl and Gpp(NH)p on [3H][Dmt1]DALDA binding
Membranes prepared from CHO-K1 cells expressing hMOR were incubated with [3H][Dmt1]DALDA (0.010-2.000 nM) for 60 min at 25°C in the presence or absence of NaCl (100 μM) and Gpp(NH)p (0.1-100 μM). Nonspecific binding was assessed by including unlabeled [Dmt1]DALDA or naloxone. Kd and Bmax were determined by fitting the data to a one-site binding model using nonlinear regression. Data are presented as mean ± S.E.M.; n is number of independent determinations; P < 0.05 compared with Tris-HCl buffer (t test).
Bmax | Kd | n | |
|---|---|---|---|
| fmol/mg | nM | ||
| Tris-HCl buffer | 923 ± 38 | 0.199 ± 0.019 | 6 |
| + NaCl (100 mM)/Gpp(NH)p (10 μM) | 691 ± 36* | 0.430 ± 0.045* | 3 |
| + Gpp(NH)p (0.1 μM) | 902 ± 24 | 0.182 ± 0.016 | 4 |
| + Gpp(NH)p (1.0 μM) | 798 ± 51 | 0.209 ± 0.030 | 4 |
| + Gpp(NH)p (10 μM) | 1075 ± 74 | 0.176 ± 0.010 | 4 |
| + Gpp(NH)p (100 μM) | 911 ± 27 | 0.233 ± 0.017 | 5 |
| + NaCl (100 mM) | 553 ± 28* | 0.432 ± 0.024* | 3 |