By Karla Gale

Cheap Viagra and other phosphodiesterase-5 inhibitors may delay or even reverse cardiac damage associated with Duchenne muscular dystrophy, according to animal research reported in the May 13 issue of the Proceedings of the National Academy of Sciences.

Absence of dystrophin causes the weakness and muscle wasting of Duchenne muscular dystrophy, as well as cardiomyopathy and cardiac failure, Dr. Christine C. Des Rosiers noted in correspondence with Reuters Health.

Previous research showed that nitric oxide (NO) signaling is defective in the hearts of mdx mice, a model of Duchenne muscular dystrophy. “Downstream of NO signaling, cyclic guanine monophosphate (cGMP) acts a secondary messenger,” she explained. “Enhanced cGMP signaling prevents and reverses pressure-overload hypertrophy.”

“In this study,” she said, “we tested the hypothesis that activating the cGMP pathway, to overcome defective NO signaling, confers beneficial effects upon the dystrophin-deficient mouse heart. Given that Viagra (Generic Viagra Super Active) works by interfering with an enzyme that reduces levels of cGMP, we chose this pharmacological approach to test our hypothesis.“

Starting with 6-week old mdx mice, the scientists injected them daily with Generic Viagra Online for 6 weeks. Compared with control treatment, Viagra treatment improved contractile performance and preserved mitochondrial metabolic status and sarcolemma integrity in the dystrophin-deficient heart, the researchers report.

“Viagra appears to be safe and well tolerated by adults. Whether this drug will be equally well tolerated by children, especially when administered chronically, remains to be determined in clinical studies,” Dr. Des Rosiers said.

Continuing, she noted: “The industry is also developing molecules that can increase cGMP signaling … by direct stimulation of soluble guanylate cyclase (one form of the enzymes responsible for the generation of cGMP within cells). In animals, these molecules have been shown to have effects similar to that of phosphodiesterase inhibitors.”

Dr. Des Rosiers believes that increased cGMP signaling would benefit the skeletal muscle as well.

“In fact, a recent study showed that tadalafil, another drug from this family, improved skeletal muscle damage in mice afflicted with Duchenne muscular dystrophy,” the researcher said. “Whether Canadian Viagra has the same beneficial effects remains to be determined, but appears likely to be so.“