KINETICS OF [H-3]-LABELED FLUNITRAZEPAM BINDING TO MEMBRANE-BOUND BENZODIAZEPINE RECEPTORS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 21  (1) , 57-65
Abstract
The kinetics of [3H]lunitrazepam binding to synaptosomal (P2) membranes from rat cerebral cortex was studied. The pseudo-1st order association at 0.degree. was curvilinear, and the association rate was increased with increasing concentrations of ligand. The association curve was resolved best as 2 linear exponentials, representing a fast and a slow component. The percentage of each association component varied with the ligand concentration. Association was slightly decreased in the presence of GABA. Dissociation at 0.degree. C, whether equilibrium binding had occurred at 0.degree. or 37.degree. C, was also biphasic. The dissociation of the complexes was more rapid at higher concentrations of ligand. Dissociation was slower in the presence of GABA, and this effect was more pronounced at higher concentrations of ligand. Prolonged preincubation at 37.degree. either in the presence or in the absence of [3H]flunitrazepam also decreased the dissociation rate. Dissociation was faster before equilibrium than after equilibrium had been reached. One homogeneous type of benzodiazepine receptor with 2 interconvertible conformations was discussed.