Rather than functioning independently, receptors that control normal heart function -- beta-adrenergic receptors and angiotensin II receptors -- join to form receptor complexes, the researchers found. What's more, drugs used to treat heart failure by blocking a single receptor actually have a dual effect, the Duke team reports in a forthcoming issue of the American Heart Association journal Circulation. Instead of only blocking the function of one form of receptor, the drugs -- known as beta blockers and angiotensin II receptor blockers -- restrict the activity of both.
The finding suggests that patients might not need the multiple blockers commonly prescribed to treat heart failure, said Howard Rockman, M.D., professor of medicine and senior author of the study. A single drug designed to efficiently block both receptors might do the job, he suggested. The National Institutes of Health and the Burroughs Wellcome Fund funded the research.
The activation of beta-adrenergic and angiotensin receptors both alter the activity of the heart. Beta-adrenergic receptors respond to the hormone adrenaline, while angiotensin receptors respond to the hormone angiotensin. Dysfunction of both receptor systems is a hallmark of heart failure, a progressive disorder that affects about 5 million people in the United States.
Cardiologists view the beta-adrenergic receptors as the "life-lines" of the heart, Rockman explained. These receptors control the amount of blood delivered to the tissues of the body in response to environmental situations such as exercise or stress. In heart failure patients, chronic stress leads the body to produce an excess of adrenaline, over-stimulatin
Contact: Kendall Morgan
Duke University Medical Center