Nav: Home

Zebrafish teach researchers more about atrial fibrillation

January 21, 2020

Researchers from the Faculty of Health and Medical Sciences have shown a possible link between a genetic variation and the widespread type of cardiac arrhythmia, atrial fibrillation.

The scientists conducted the study in zebrafish, which is a recognised scientific animal model within cardiac research.

Here, researchers from the University of Copenhagen in Denmark and the Max Planck Institute in Germany put special focus on the gene pitx2c. The result came as a surprise to them, says Assistant Professor Pia Lundegaard from the Department of Biomedical Sciences.

'It seems that we may also have to think of atrial fibrillation as an atrial cardiomyopathy - that is, a challenged heart - rather than as a purely electrical disorder', she says.

Defects in muscle fibres and mitochondria

Contrary to expectations, the researchers did not find any disturbances in the ion channels that spread electrical signals between the heart's muscle cells.

Instead, they found defects in the structure of the heart muscle itself and in the mitochondria that normally function as the cell's power plant. The defects already occurred in the foetal stage of the fish and deteriorated exponentially with age.

'Usually the structure of a cross-section of the sarcomeres - the muscle fibres - shows a very fine grid structure. But in these fish, it is clear that the structure is disorganised from a very early stage', explains Pia Lundegaard, adding:

'At the same time, we can see in our pictures that there are too many mitochondria. So, it seems that the heart is trying to compensate for the defective muscle fibres. This indicates that there is a structural defect in the heart which over time will cause a rhythm defect'.

Antioxidant prevents defects

According to the research study, the increased number of mitochondria appears to aggravate the negative spiral, the reason being that also the mitochondria are defective and gradually increase the level of so-called oxidative stress.

In other words, they create an unhealthy environment in the cell where different proteins are broken down.

At the same time, however, the researchers found that early and ongoing treatment with the antioxidant NAC seemed to counteract the defect and in the long term prevent atrial fibrillation in the fish.

However, Pia Lundegaard from the Department of Biomedical Sciences emphasises that heart patients should not stockpile antioxidants such as NAC for that reason.

She points out that the studied gene is just one of many possible factors behind atrial fibrillation, which is also greatly influenced by the individual's lifestyle.

In addition, to better demonstrate the effect of the studied gene, the gene defect has been designed to be stronger in the test fish than commonly seen in humans.

Better control procedures

The improved understanding of the disease nevertheless provides greater insight into the reason why some atrial fibrillation medications may not always work as well as one might wish.

Therefore, Pia Lundegaard hopes that the result of the new research will be that more practitioners reconsider the possible causes behind rhythm disorders.

'The rhythm disorder may be secondary to what is actually the problem. We hope that in the future, we can develop better control procedures that will prevent some people's hearts from being worn down for a long time and eventually fail', she says.

The next step for the research group is to investigate other genes associated with atrial fibrillation. Likewise, the group will investigate whether antioxidants other than NAC can prevent the disorder.
-end-


University of Copenhagen The Faculty of Health and Medical Sciences

Related Mitochondria Articles:

Unexpected insights into the dynamic structure of mitochondria
As power plants and energy stores, mitochondria are essential components of almost all cells in plants, fungi and animals.
Mitochondria are the 'canary in the coal mine' for cellular stress
Mitochondria, tiny structures present in most cells, are known for their energy-generating machinery.
Master regulator in mitochondria is critical for muscle function and repair
New study identifies how loss of mitochondrial protein MICU1 disrupts calcium balance and causes muscle atrophy and weakness.
Oxygen deficiency rewires mitochondria
Researchers slow the growth of pancreatic tumor cells.
Self-cannibalizing mitochondria may set the stage for ALS development
Northwestern Medicine scientists have discovered a new phenomenon in the brain that could explain the development of early stages of neurodegeneration that is seen in diseases such as ALS, which affects voluntary muscle movement such as walking and talking.  The discovery was so novel, the scientists needed to coin a new term to describe it: mitoautophagy, a collection of self-destructive mitochondria in diseased upper motor neurons of the brain that begin to disintegrate from within at a very early age.
Uncovering the presynaptic distribution and profile of mitochondria
In a recent study published in the Journal of Neuroscience, scientists from the MPFI and the University of Iowa CCOM have provided unprecedented insight into the presynaptic distribution and profile of mitochondria in the developing and mature calyx of Held.
Temple researchers identify new target regulating mitochondria during stress
Like an emergency response team that is called into action to save lives, stress response proteins in the heart are activated during a heart attack to help prevent cell death.
Runaway mitochondria cause telomere damage in cells
Targeted damage to mitochondria produces a 'Chernobyl effect' inside cells, pelting the nucleus with harmful reactive oxygen species and causing chromosomal damage.
Interplay between mitochondria and nucleus may have implications for new treatment
Mitochondria, the 'batteries' that produce our energy, interact with the cell's nucleus in subtle ways previously unseen in humans, according to research published today in the journal Science.
Dissolving protein traffic jam at the entrance of mitochondria
Researchers from Freiburg discovered a novel mechanism that ensures obstacle-free protein traffic into the powerhouse of the cell.
More Mitochondria News and Mitochondria Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.