Influence of beta-adrenoceptor blocking drugs on lipid-protein interaction in synaptosomal membranes. An ESR study.

The influence of the beta-adrenoceptor blocking drugs atenolol, doberol, propranolol and exaprolol on synaptosomal membranes was studied using ESR spectroscopy of stearic acid spin labeled at the 16th position. The drugs changed the ESR spectra of the label in the membranes, where in addition to changes of a fluid lipid component they increased the proportion of a motionally-restricted component. No motionally-restricted component was found in the samples prepared from brain total lipid liposomes treated with the drugs. The drug propensities at 20 mmol/l concentration to increase the proportion of the motionally-restricted component in the following order, control less than doberol approximately atenolol less than or equal to propranolol less than exaprolol did not correlate with their potency to influence the dynamics of the bulk lipid membrane phase. The motionally-restricted component induced by exaprolol increased with raising temperature and prolongation of time of the sample incubation. The results indicate that the beta-adrenoceptor blocking drugs influence lipid-protein interaction in the synaptosomal membranes, which could be important for elucidation of their mechanism of biological membrane activities.