adrenergic-blocking drugs

adrenergic-blocking drugs

Alpha-adrenergic receptors are in the muscle walls of arteries. Stimulation of these cause the arteries to narrow. Blockage will cause the arteries to widen. Beta1 adrenergic receptors are in the heart. Stimulation causes an increase in heart rate and force. Beta2 adrenergic receptors are in the muscles of the BRONCHI and of the arteries, in both of which stimulation causes relaxation. Blocking drugs that block both ß1 and ß2 slow the heart and cause constriction of the air passages and the arteries. This can be dangerous to asthmatics. Some beta-blockers are relatively selective for the heart and are less likely to constrict the air passages. See also ALPHA-ADRENOCEPTOR BLOCKING DRUGS.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005