Binding affinities (pK i values) of yohimbine and its bivalent analogs on human α2A-, α2B-, and α2C-adrenoceptors expressed in Chinese hamster ovary calls
| Compound | α2A | α2B | α2C |
|---|---|---|---|
| Yohimbine | 8.52 ± 0.041-a | 8.00 ± 0.10 | 9.17 ± 0.021-b |
| MK-912 | 9.06 ± 0.041-a | 9.76 ± 0.10 | 10.2 ± 0.021-b |
| n = 2 | 7.03 ± 0.121-a | 5.50 ± 0.07 | 8.46 ± 0.121-b |
| n = 3 | 6.74 ± 0.031-a | 5.69 ± 0.04 | 8.24 ± 0.071-b |
| n = 4 | 7.27 ± 0.151-a | 6.40 ± 0.08 | 8.08 ± 0.171-b |
| n = 5 | 8.21 ± 0.071-c | 6.55 ± 0.10 | 7.97 ± 0.131-d |
| n = 6 | 8.35 ± 0.101-c | 6.54 ± 0.16 | 8.16 ± 0.041-d |
| n = 7 | 8.51 ± 0.081-c | 7.24 ± 0.07 | 8.63 ± 0.111-d |
| n = 9 | 8.40 ± 0.121-c | 7.03 ± 0.02 | 8.63 ± 0.101-d |
| n = 18 | 7.34 ± 0.101-a | 6.60 ± 0.04 | 8.43 ± 0.011-b |
| n = 24 | 6.39 ± 0.101-a | 5.41 ± 0.02 | 8.30 ± 0.101-b |
pK 1 values are the negative log of theK 1 value, determined using the Cheng and Prusoff equation: K 1 = [IC50]/(1 +[RL]/K RL), where RL is radioligand used. See Materials and Methods. [3H]Rauwolscine was the radioligand used. Values are expressed as the mean ± S.E.M. ofn = 4 to 6 experiments. Statistical analysis was carried out by one-way analysis of variance followed by Tukey's test.
↵1-a pK 1 values for the analog on the α2A-AR subtype are significantly different from the pK 1 values for the analog on the α2B- and α2C-AR subtype
↵1-b pK 1 values for the analog on the α2C-AR subtype are significantly different from the pK 1 values on the α2A- and α2B-AR subtypes.
↵1-c Indicates that the pK 1 values for the analog on the α2A-AR subtype are significantly different from the pK 1 values for the analog on the α2B-AR subtype.
↵1-d pK 1 values for the analog on the α2C-AR subtype are significantly different from the pK 1 values for the analog on the α2B-AR subtype.