Viagra improves blood flow
The anti-impotence drug Viagra may help save people with muscular dystrophy from an early death, a study suggests.
Researchers found the way the drug works to combat impotence may also help ward off heart failure in muscular dystrophy patients.
Tests on mice with a version of the disease showed the drug helped keep their hearts working well.
The Montreal Heart Institute study appears in Proceedings of the National Academy of Sciences.
Muscular dystrophy is a genetic condition causing wasting of the muscles.
The first signs of muscular weakness appear at roughly age five, leading to a progressive loss in the ability to walk by the age of 13.
People with the condition are also at a higher risk of heart failure due to a weakening of the muscles which keep the organ pumping strongly.
For this reason, many people with Duchenne muscular dystrophy - the most common form of the condition - die in early life, often in their 20s or 30s.
The Montreal team found that Viagra - known technically as sildenafil - prevents the loss of a molecule, cGMP, which plays a key role in keeping blood vessels dilated.
In the penis, this increases blood flow, and helps to combat impotence.
But in the heart it helps to ensure the organ itself receives a proper supply of blood, and remains healthy and strong.
With the heart in a strong condition, it is more able to withstand the impact of weakening muscle cells caused by muscular dystrophy.
Viagra works by blocking an enzyme, PDE5, which breaks down cGMP.
Professor Jean-Claude Tardif, director of the Montreal Heart Institute Research Centre, said: "These experimental results give us hope that one day it will be possible to treat with this approach cardiac problems in patients with muscular dystrophy, and perhaps even treat other heart diseases."
The researchers also inserted a gene that increased cGMP production in the mice's heart cells, and found that this helped the animals to maintain normal cardiac function.
Dr Marita Pohlschmidt, director of research at the Muscular Dystrophy Campaign, said the research was interesting.
However, she added: "It is important to remember that benefits seen in animals do not always translate into human medicine.
"Although this is promising, it is still very early days and we look forward to further research that will demonstrate the impact it might have for people with muscular dystrophy."