Preservation of "peripheral" benzodiazepine receptors: differential effects of freezing on [3H]Ro 5-4864 and [3H]PK 11195 binding.
The equilibrium binding constants of [3H]Ro 5-4864 (a "peripheral" benzodiazepine receptor ligand) to renal membranes preserved by various freezing techniques were investigated. The Bmax for [3H]Ro 5-4864 binding to membranes from kidneys preserved as unwashed homogenates stored at -80, -20, or 5 degrees C, whole kidneys stores at -20 or 5 degrees C or as washed homogenate stored at -20 degrees C was significantly decreased (approximately 35%). Only when kidneys were frozen intact (using a dry-ice/acetone slurry) and stored at -80 degrees C was the density of [3H]Ro 5-4864 binding unchanged. However, the Bmax of [3H]PK 11195 (a putative "peripheral" benzodiazepine receptor antagonist) binding to renal membranes was unchanged following storage techniques that reduced the density of [3H]Ro 5-4864 binding 38%. No change was observed in the Kd values for [3H]Ro 5-4864 and [3H]PK 11195 binding to renal membranes preserved under any condition tested. These results demonstrate a method for the preservation of [3H]Ro 5-4864 binding to renal membranes, and suggests that [3H]Ro 5-4864 and [3H]PK 11195 bind to unique sites on or near the "peripheral" benzodiazepine receptor. [corrected]
D000315:Adrenalectomy; D000818:Animals; D001570:Benzodiazepinones / Q000378:metabolism*; D005615:Freezing; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000378:metabolism*; D007668:Kidney / Q000032:analysis*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000032:analysis*; D014021:Tissue Preservation; D014316:Tritium
D001570:Benzodiazepinones; D007546:Isoquinolines; D011963:Receptors, GABA-A; D014316:Tritium; C028513:4'-chlorodiazepam; C037850:PK 11195