This hormone may offer new treatment for heart rhythm disorder

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In a new study, researchers found that a hormone that helps regulate bone mass is also produced by the heart and could be used to treat people with a dangerous heart rhythm disorder.

The research was conducted by a team at the University of Oxford.

Until now, the hormone calcitonin was only thought to be produced by the thyroid gland, with no known effects on the heart.

This research showed that cells in the upper chambers of the heart, known as the atria, produce approximately 16 times more calcitonin than cells in the thyroid.

The team also found that the hormone plays a vital role in reducing atrial scarring.

Such scarring makes it harder for electrical impulses to travel smoothly through the atria and can cause them to beat in a chaotic manner, known as atrial fibrillation (AF).

The researchers studied muscle cells from atrial biopsies taken from people undergoing heart surgery and found that they released calcitonin.

Interestingly, cells from biopsies of patients with severe AF produced six times less calcitonin.

Looking further, they saw that the calcitonin receptor was present in atrial cells responsible for producing collagen, a major component of scar tissue.

When the team treated these cells—called fibroblasts—with calcitonin the cells produced 46% less collagen.

Further experiments showed that mice that were unable to produce calcitonin in their hearts developed 2.5 times more atrial scar tissue, compared to mice with normal levels of calcitonin.

They also developed AF at a younger age and had approximately 16 times longer episodes of AF.

Strikingly, atrial scarring and AF were completely prevented in mice whose hearts produced greater amounts of calcitonin.

Around 1.4 million people in the UK have been diagnosed with atrial fibrillation, which can significantly increase a person’s risk of stroke by promoting the formation of blood clots in the heart that may then travel to the brain and block blood vessels there.

The researchers now hope that this new heart hormone and its receptor may hold the key to treating this potentially devastating condition.

One author of the study is Professor Svetlana Reilly.

The study is published in Nature.

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