Synthesis and binding to beta-adrenergic receptors of p-aminobenzyl analogues of practolol and atenolol.
The p-aminobenzyl analogues (8a and 8b, respectively) of the cardioselective beta-adrenergic receptor antagonists practolol and atenolol were prepared from the corresponding phenoxymethyloxiranes in 30 and 13% yields, respectively. The dissociation constants for the beta-adrenergic receptor were measured in membrane preparations of rat heart and lung. In membranes from the heart (which contain mostly beta 1-adrenergic receptors), the affinities of the derivatives and parent compounds were similar. By contrast, in membranes from the lung (which contain mostly beta 2-adrenergic receptors), the derivatives were more potent than the parent compounds. Thus, the cardioselectivities of the p-aminobenzyl analogues 8a and 8b were about one-sixth those of the respective parents.