Influence of polymeric effectors on binding of 3H-dihydroalprenolol to beta-adrenergic receptor of rat brain.

The significance of anionic and cationic charges of glycocalyx, phospholipid or protein, etc. on the cell surface of the rat brain was examined for beta-adrenoceptors using the radioligand binding assay method. Thus, this experiment was designed to assess the effects of polymeric effectors, DNA, heparin, polymyxin B, histone, gelatin, colominic acid and bovine serum albumin (BSA), on the affinity of beta-adrenoceptors. The rat brain was used and the beta-adrenoceptor binding assay was carried out using 3H-dihydroalprenolol as a radioligand. Polymyxin B, DNA and heparin significantly caused a reduction in the maximum number of beta-adrenoceptors (Bmax), but only small changes were observed with histone, gelatin, BSA and colominic acid. Only DNA induced a decrease in the value of the dissociation constant (Kd) of beta-adrenoceptors. These results suggest that anionic or cationic charges in the environment of the receptor sites could have a crucial role in drug-receptor interaction.