Changes in adrenal benzodiazepine receptors in spontaneously hypertensive rats

[3H]PK-11195[1-(2-chlorophenyl)-N-methyl-N-(1-methyl [2,3-3H]propyl)-3-isoquinolinecarboxamide] is a labeled ligand with high affinity selectively binding to “peripheral type” benzodiazepine receptors. The kinetic constants of [3H]PK-11195 binding to the adrenal homogenates of spontaneously hypertensive rats (WKY) were measured. Scatchard analysis of the specific binding showed a single class of binding site with a maximal capacity (Bmax) of 11.9+/-1.7 and 22.8+/-1.9 pmol/mg protein for SHR and WKY, and an apparent equilibrium dissociation constant (KD) of 8.1+/-1.9 and 8.6+/-1.9 nM for SHR and WKY, respectively.
These results demonstrated that the adrenal benzodiazepine binding sites in SHR are less than those in WKY, but the affinities are similar.