Viagra relatives may shrink abnormally large hearts 1
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Compounds related to Viagra, which is already in clinical trials to prevent heart failure, may also counter the disease in a different way, according to a study published online today in the journal Circulation Research. The results hold promise for the design of a new drug class and for its potential use in combination with Viagra or beta blockers.
In heart failure, which affects about 5.7 million Americans, the heart gradually loses the ability to pump with enough force to supply the body with blood. One reason for lost pumping strength is the mass death of heart muscle cells seen in many heart diseases (e.g. heart attack).
Fewer remaining muscle cells must then push around the same amount of blood, and hard working muscles grow. Unlike the healthy bulging of an athlete’s bicep, abnormal muscle growth (pathogenic hypertrophy) in diseased hearts thickens chamber walls, slows the heartbeat and causes potentially fatal arrhythmias. Hypertrophy is a major risk factor for the development of heart failure as well.
Recent efforts to reverse hypertrophy include a clinical trial, sponsored by Viagra manufacturer Pfizer, and the National Heart, Lung, and Blood Institute (NHLBI), looking at whether Viagra (sildenafil) can treat moderate heart failure and reduce hypertrophy. Along with increasing blood flow in arteries, Viagra interferes with phosphodiesterases (PDEs), enzymes that break down the messenger molecule called cyclic guanosine monophosphate (cGMP), which would otherwise “put the brakes on” heart muscle cell growth.