By Steven Reinberg
HealthDay Reporter
(HealthDay News) -- Patients with Duchenne
muscular dystrophy often suffer from heart failure, but Viagra might
prevent or delay the onset of this condition, a new Canadian study
finds.
In experiments with mice, researchers showed that Viagra (sildenafil)
improved heart performance by preventing the breakdown of a compound
called cGMP, which relaxes smooth muscle.
"Duchenne muscular dystrophy is a crippling disease that affects both
skeletal muscle and cardiac muscle," said lead researcher Christine Des
Rosiers, a professor of cardiology in the department of nutrition at the
University of Montreal. "Currently, there is a need for the development of
more effective treatment strategies for patients affected with this
disease."
In their experiments, the researchers used mice bred to mimic Duchenne
muscular dystrophy. Then the scientists gave the rodents doses of Viagra
comparable to those taken by men for erectile dysfunction.
The researchers found that Viagra improved heart function in the mice
by preventing the breakdown of cGMP.
In a further experiment, the researchers inserted a gene into the
hearts of the mice that increased the production of cGMP. The result: The
mice were able to maintain normal heart function.
The findings are published in this weeks issue of the Proceedings of
the National Academy of Sciences.
"Our findings substantiate benefits for the dystrophic heart using a
pharmacological approach, namely with sildenafil, which is safe,
well-tolerated and currently available for clinical use," Des Rosiers
said. "Hence, this could provide the basis for a new avenue for the
treatment. Furthermore, the benefits of this therapeutic approach would be
expected to extend beyond the heart to affected skeletal muscle and other
tissues."
Dr. Valerie A. Cwik, medical director and vice president of research at
the Muscular Dystrophy Association, said there's a need for new approaches
to the treatment of heart failure in patients with Duchenne and other
forms of muscular dystrophy.
"The findings presented by these authors are interesting and certainly
have potential clinical implications for the various forms of
dystrophinopathy [heart damage]," she said, adding that heart failure is a
major cause of illness and death in late-stage Duchenne muscular
dystrophy.
"At the present time, there is no consensus or standard of care for
optimal management of the cardiac complications of dystrophinopathies, and
further research in this area is clearly needed," Cwik said.
While Viagra hasn't been tested in humans to see if it benefits
muscular dystrophy patients, it has been available for years and appears
to be safe, Cwik noted.
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