Binding of fluorescent and radiolabelled alprenolol to intact cultured brain cells and liposomes.

Beta-adrenergic antagonist L-alprenolol was labelled for radioactivity and UV fluorescence, and the binding to intact cultured chicken brain cells under equilibrium conditions, as the model of the experiments in vivo, was probed. The application of fluorescent label did not explore any cell type or cell particle with enhanced binding. The analysis of the radiolabelled alprenolol-binding revealed a non-specific accumulation on the surface of these cells, which was inhibited by unlabelled alprenolol excess, however, this is the peculiarity of the specific binding. Our results emphasize that for the characterization of membrane receptors of intact cells, the accurate separation of specific and non-specific binding is required. The application of a ligand concentration as low as possible and a very effective washing procedure for the removal of the unbound (and the bulk of the nonspecifically bound) label is recommended.