[Comparative study of beta-adrenoreceptors of rat brain synaptic membranes].

Affinity of beta-adrenoreceptors in the rat brain synaptic membranes to agonists isoproterenol and norepinephrine, as well as to antagonist 125I-hydroxybenzylpindolol is lower in young (1 month) and old (24--26 months) than in mature (8--12 months) rats. Desensitization toward isoproterenol is expressed in the young ones only. In the old but not in other groups simultaneous action of isoproterenol and N-ethylmaleimide decreases the following binding of the antagonist while the same agents added separately produced no effect. It is suggested that beta-adrenoreceptors undergo age-related changes in their conformational state due to modification of the membrane environment.