Relationship between adrenergic blocking and antihypertensive effects of beta receptor antagonists

In hypertensive patients, whose blood pressure was decreased by racemic propranololthe dextrorotatory isomer had no antihypertensive effect. The differences in antihypertensive activity of racemic and dextrorotatory propranolol cannot be explained by different plasma levels; the data indicate that the hypotensive effect of propranolol is due to beta receptor blockade.