Characterization of peripheral-type benzodiazepine recognition sites in the rat spinal cord.
The binding of [3H]Ro 5-4864 to membranes prepared from spinal cord of the adult rat has been studied in vitro. At 4 degrees C, the binding of [3H]Ro 5-4864 reached equilibrium by 120 min, and was rapidly reversible (dissociation t0.5 = 21 min). The [3H]Ro 5-4864 bound with a high affinity (Kd approximately equal to 3 nM) to a single, saturable population of binding sites (Bmax = 27 pmol/g tissue wet weight). Activation of receptors for gamma-aminobutyric acid with 10 microM muscimol did not alter these binding parameters. The drugs Ro 5-4864, diazepam and flunitrazepam were potent inhibitors of this binding (Kis of 10(-9)-10(-8) M) whereas clonazepam, CL 218,872 and Ro 15-1788 were weak inhibitors (Kis greater than 10(-5) M). A comparison of the binding of [3H]Ro 5-4864 in spinal cord with that in other areas of the CNS revealed that whereas the binding affinity was similar in all regions, membranes from spinal cord contained a slightly greater number of binding sites than cerebral cortex and cerebellum, and approximately one-third of the number present in the olfactory bulb. The characteristics of the binding of [3H]Ro 5-4864 obtained in this study are consistent with this ligand binding to peripheral-type benzodiazepine recognition sites in membranes from spinal cord.
D000818:Animals; D001569:Benzodiazepines / Q000378:metabolism*; D001570:Benzodiazepinones / Q000378:metabolism; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D003975:Diazepam / Q000378:metabolism; D005445:Flunitrazepam / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*
D001570:Benzodiazepinones; D001569:Benzodiazepines; C028513:4'-chlorodiazepam; D005445:Flunitrazepam; D003975:Diazepam