Dystrophic hearts treated with viagra

Published Date
22/12/2008
Author
Super Administrator
Category
Research

Research update about the news that viagra could help treat the hearts of people with Duchenne and Becker muscular dystrophy.

The article published on 13 May by the group of Christine des Rosiers of the Montreal Heart Institute and the Université de Montréal in the journal PNAS, has pinpointed a possible therapeutic target to address the cardiomyopathy seen in Duchenne and Becker muscular dystrophies. The researchers report that in a mouse model for Duchenne the hearts seem to become stronger when the animals were treated with a drug called Sildenafil also known as Viagra.

Contents:

  • The theory and the experiments
  • The results of the study
  • The paper
  • More about Duchenne and Becker muscular dystrophy

The theory and the experiments

Khairallah et al investigated a specific biochemical pathway through which the heart’s cells communicate with their surrounding. In science these kinds of pathways are described as “cell signalling pathways.” In this case the researchers investigated a particular pathway – called the cGMP pathway – that can result in several types of cardiomyopathy if it does not function properly. The rationale behind the study was that activation of this signalling pathway may enable the scientists to improve the functioning of the heart and to slow or prevent the formation of cardiomyopathy.

The researchers took two approaches to investigate this using an animal model of Duchenne muscular dystrophy – called the mdx mouse. First, they genetically modified the mdx mouse so that the animals produced higher than normal levels of a protein that activates the cGMP pathway. The second approach was to administer a drug called Sildenafil – or Viagra – to the normal mdx mouse. Viagra is known as an anti-impotence drug and acts through increasing the blood flow in the penis by activating the cGMP pathway. The scientist hypothesised that if it had the same effect on the heart it would improve its function and could be developed as treatment for cardiomyopathy.

The results of the study

The group compared the function of the heart in all three types of mice – the genetically modified mdx mice, the mdx mice given Sildenafil and the untreated mdx mice. The untreated mdx mice showed deterioration of their heart muscle as they got older. But both in the genetically modified mdx mice and those mice given Sildenafil, the heart muscle maintained its ability to contract and therefore pump blood around the body. The heart muscle cells were also better protected against mechanical damage. This led the scientists to conclude that activation of the cGMP signalling pathway had a positive effect on the mdx mouse heart.

Commenting on the study, Dr Marita Pohlschmidt, Director of Research at the Muscular Dystrophy Campaign, said:

The findings published in PNAS suggest that the drug Sildenafil can have a positive effect on the heart in an animal model of Duchenne, but 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.

More about Duchenne and Becker muscular dystrophy

Duchenne and Becker muscular dystrophies are caused by a mutation in the gene that encodes the muscle protein dystrophin. The major effect the mutation has is to cause weakening and wasting of muscle. In Duchenne, the mutation prevents production of the dystrophin protein resulting in a more severe condition than Becker, where the mutation usually causes a shorter, but still partially functional protein. As well as the effect on muscles, the lack of dystrophin is known to also affect the heart and can cause a condition called cardiomyopathy. This is where the heart becomes abnormally large, limiting its ability to pump blood around the body. Cardiomyopathy is a major cause of death in Duchenne.

Find out more about Duchenne muscular dystrophy and Becker muscular dystrophy.

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