Affinities of histamine and histaprodifens at hH1R, hgpE2H1R, hgpNgpE2H1R, and gpH1R coexpressed with RGS4 in Sf9 cell membranes in the equilibrium competition binding assay [3H]MEP competition binding in Sf9 membranes expressing hH1R, hgpE2H1R, hgpNgpE2H1R, and gpH1R in combination with RGS4 was determined in presence of 5 nM [3H]MEP as described under Materials and Methods. Data were analyzed by nonlinear regression and were best fit to one-site (monophasic) competition curves. The pKi values were calculated according to the Cheng and Prusoff (1973) method. Data shown are the means ± S.E.M. of at least three experiments, each one performed in duplicate with independent membrane preparations.
Cpd | pKi | ||||||
|---|---|---|---|---|---|---|---|
| hH1R | hgpE2H1R | hgpNgpE2H1R | gpH1R | ||||
| 1 | 5.62 ± 0.03 | 5.74 ± 0.04 | 5.75 ± 0.12 | 5.50 ± 0.03 | |||
| 2 | 6.47 ± 0.11 | 6.21 ± 0.08 | 6.06 ± 0.08 | 6.38 ± 0.11 | |||
| 3 | 6.33 ± 0.09 | 6.23 ± 0.03 | 6.29 ± 0.10 | 7.11 ± 0.10 | |||
| 4R | 6.14 ± 0.07 | 5.96 ± 0.09 | 6.00 ± 0.07 | 6.94 ± 0.08 | |||
| 4S | 5.40 ± 0.09 | 5.53 ± 0.08 | 5.58 ± 0.06 | 6.12 ± 0.08 | |||
| 5 | 6.60 ± 0.07 | 5.92 ± 0.04a | 6.01 ± 0.02a | 7.33 ± 0.08 | |||
| 6R | 6.08 ± 0.06 | 5.94 ± 0.06b | 5.72 ± 0.08c | 6.74 ± 0.02 | |||
| 6S | 6.40 ± 0.15 | 6.04 ± 0.11b | 5.76 ± 0.04c | 6.38 ± 0.17 | |||
|
7
| 6.67 ± 0.01 | 6.37 ± 0.08 | 6.58 ± 0.18 | 7.33 ± 0.14 | |||