TABLE 1

Binding affinity values (pKI) of prazosin, 5-methylurapidil, RS 100329, and BMY 7378 derived from the inhibition of [3H]prazosin specific binding to proximal and distal rat CE segments

The Hill slopes (nH) of inhibition curves are presented.

ProximalDistal
pKIHapKILbnHnpKIHpKILnHn
Prazosin9.03 ± 0.170.84 ± 0.1749.22 ± 0.160.83 ± 0.136
5-MU9.28 ± 0.120.80 ± 0.1649.09 ± 0.170.84 ± 0.084
RS 1003299.32 ± 0.180.83 ± 0.1749.34 ± 0.101.01 ± 0.134
BMY 73788.98 ± 0.47 (48%)6.28 ± 0.42 (52%)0.53 ± 0.12c48.91 ± 0.39 (52%)5.92 ± 0.57 (48%)0.42 ± 0.08c5
  • 5-MU, 5-methylurapidil.

  • a pKI at high-affinity binding site.

  • b pKI at low-affinity binding site; values between parenthesis in BMY 7378 row represent the total percentage of high- and low-affinity sites; Data represent mean ± S.E.M. from n experiments with tissues taken from different rats.

  • c Significantly different from 1 (P < 0.05).