Beta blockers are drugs that block the stimulating action of noradrenaline—the "fight or flight" hormone—thereby reducing the force of the heartbeat and the workload of the heart. Today they are widely used to treat angina, high blood pressure, and irregular heart rhythms, and to improve heart muscle function in cardiomyopathies.
Beta blockers were developed in 1956 by Sir James Black [b. 1924), a Scottish doctor working for ICI in the United Kingdom. Black had personal as well as professional reasons for his interest in cardiovascular disease. His father had a fatal heart attack following a car accident, making Black ponder the role of stress in producing adrenaline, angina, and heart attacks.
At the time, many of the drugs used to treat angina were vasodilators (causing dilation of the blood vessels), in particular nitrites, which increased the blood supply, and therefore the amount of oxygen to the heart. However, these caused unpleasant side effects such as flushing of the face and headaches. Black hypothesized that instead of treating angina by increasing the oxygen supply to the heart, it might be possible to do so by reducing the demands made on the heart.
Black acknowledges the influence of the 1948 paper by U.S. scientist Raymond Ahlquist, which suggested that the effects of noradrenaline of speeding up and slowing down the heart are mediated by different receptors in the target organ, which he called alpha and beta receptors. Black and his colleagues substituted different chemicals to find structures that blocked the beta receptor without stimulating it. Eventually they synthesized propranolol, the first beta blocker to be marketed. Since then many different beta-blocking agents have been produced.
