Potencies and efficacies of phenylhistamines 7, 8, and 9 at hH1R coexpressed with RGS4 and at hH2R-GsαS expressed in Sf9 cell membranes in the steady-state GTPase assay and comparison with imidazolylpropylguanidine 19
Steady-state GTPase activity in Sf9 cell membranes expressing hH1R and RGS4 or hH2R-GsαS was determined as described under Materials and Methods. Data were analyzed by nonlinear regression and were best fit to sigmoidal concentration-response curves. The efficacy (Emax) of histamine was set 1.00. The Emax values of all other compounds were referred to this value. Data shown are means ± S.E.M. of at least three experiments, each performed in duplicate. Membranes were used from independent membrane preparations.
Compound | hH1R | hH2R-GsαS | ||||
|---|---|---|---|---|---|---|
| pEC50 | Emax | pEC50 | Emax | |||
| 7 | 6.45 ± 0.02 | 0.92 ± 0.03 | 5.19 ± 0.02 | 0.46 ± 0.01 | ||
| 8 | 7.47 ± 0.02 | 0.93 ± 0.04 | 6.13 ± 0.08 | 0.82 ± 0.05 | ||
| 9 | 7.75 ± 0.11 | 0.94 ± 0.06 | 6.60 ± 0.04 | 0.18 ± 0.05 | ||
|
19
a
| 6.55 ± 0.01 | 0.56 ± 0.06 | 7.64 ± 0.05 | 0.87 ± 0.05 | ||