Table 2.
Binding affinities for various α1-adrenoceptor antagonists estimated at [3H]-silodosin binding sites in iris segments of pigmented and albino rabbits
|
Pigmented rabbit |
Albino rabbit |
|
|---|---|---|
| pKi | pKihigh (% high) pKilow | |
| Prazosin | 6.3 ± 0.3 | 9.5 ± 0.3 (50) 7.6 ± 0.2 |
| Bunazosin | 6.2 ± 0.1 | 9.3 ± 0.2 (52) 6.4 ± 0.3 |
| RS-17053 | 5.7 ± 0.3 | 8.3 ± 0.2 (43) 6.5 ± 0.1 |
| Silodosin | 9.0 ± 0.2 | ND |
| Tamsulosin | 9.1 ± 0.3 | 9.6 ± 0.4 |
| 5-Methylurapidil | 7.5 ± 0.1 | 9.1 ± 0.2 (47) 7.4 ± 0.2 |
| BMY 7378 | 6.2 ± 0.1 | ND |
Data shown are means ± SEM of four or five experiments. pKihigh and pKilow: negative logarithm of equilibrium dissociation constants at high- and low-affinity sites for antagonists tested. % high: proportion of high-affinity sites.
BMY 7378, 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione dihydrochloride; ND, not determined; SEM, standard error of the mean.