A protein that helps top sprinters to run so fast could one day boost the performance of sluggish hearts.
Sprinters get their explosive power from 鈥渇ast-twitch鈥� muscle fibres, says Joseph Metzger of the University of Michigan. These contain a protein called parvalbumin, which helps the fibres relax quickly by soaking up calcium ions inside the muscle cells. 鈥淧arvalbumin is the secret to why Marion Jones is a world class sprinter,鈥� says Metzger.
In around 40 per cent of patients with heart failure, there is a problem with how the pumping heart relaxes. This means it does not fill with blood properly between each beat. But there are no drugs available that can help.
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鈥淭o directly treat the heart to make it relax better is extremely difficult,鈥� says Stephen Ball from the Institute for Cardiovascular Research at Leeds University.
Gene therapy
For a remedy, Metzger and his colleagues looked at other muscle systems that are designed for speedy relaxation and decided to try the sprinter鈥檚 protein, parvalbumin. 鈥淲e wanted to know whether we could apply these secrets of nature to a sluggish relaxing heart,鈥� he says.
Heart cells do not naturally produce parvalbumin, so the researchers used an adenovirus to deliver the human gene for the protein into rat hearts. The treatment restored normal function in rats with slowly relaxing hearts.
But there are still many practical difficulties before parvalbumin could be used in a clinical setting. 鈥淚t does seem to accelerate relaxation,鈥� says Ball. 鈥淭he question is, how to mimic that with a drug.鈥�
Simply injecting parvalbumin into the heart would not work because the protein only has an effect if it is inside cells. Metzger says that gene therapy or attaching to parvalbumin a tag that encourages cells to take up the protein could be the answer.
Eventually, he envisages that we might have permanent implants that would monitor our hearts and take action when necessary. 鈥淏iological sensors could cause parvalbumin to be specifically activated if the heart was beginning to fail,鈥� he says.
More at: Journal of Clinical Investigation (vol 107, p191)