The catecholamine epinephrine is the preferred natural agonist for the beta adrenergic receptors, Adrb1, Adrb2 and Adrb3. Although the Adrb1 and Adrb2 receptors are important for normal cardiac function, acute stimulation can lead to cardiac failure if it becomes chronic.  This observation has led to the development of beta blockers, a class of drugs which counteract such excessive signaling and thus are commonly used to protect the heart from the adverse affects of MI, cardiac arrhythmias and hypertension.  On the other hand, in the treatment of asthma beta agonists are used to target the beta2 receptor to stimulate its bronchodilator function.

This suite of interactive pathway diagrams covers several aspects of the epinephrine and beta adrenergic receptor system.  Click any of the links below to explore the pathways of epinephrine synthesis, its signaling via beta receptors and the blockers and agonists that affect the functioning of its receptors.