Atenolol is a selective β
1 adrenergic receptor antagonist (β
1-blocker). β
1-Adrenergic receptors are located mainly in the heart and in the kidneys. β
1 Adrenergic receptor antagonists (eg. atenolol, metoprolol tartrate [
M2555], bisoprolol hemifumarate [
B3994] and nebivolol hydrochloride [
N0954]) protect the heart against the oxygen-consuming effects of sympathetic stimulation by blocking β
1 adrenergic receptors. β
1 adrenergic receptor antagonists also serve to reduce the heart rate and protect the failing heart against excessive sympathetic drive. Atenolol is a racemic mixture and its activity resides in the
S-enantiomer. (The product is for research purpose only.)