Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New findings on how cardiac arrhythmias develop

05.05.2015

Cardiac arrhythmias affect a high proportion of the aging population. Mitochondria are the ‘powerhouses of the cells’, and scientists in Cologne have now shown that even a few heart cells with reduced mitochondrial function are sufficient to trigger arrhythmias.

Mitochondria are cell organelles that are involved in many functions. They are considered to be the ‘powerhouses of the cells’ because they convert nutrients into energy.

They are involved in the regulation of programmed cell death, when a cell is no longer needed or even constitutes a risk to the body. Mitochondria have their own DNA (mitochondrial DNA, mtDNA), which accumulates point mutations in its sequence or loses large portions (mtDNA deletions) during the aging process.

If the number of altered mtDNA copies increases too much, there is a dramatic disruption of mitochondrial function and, as a result, of cell function. This phenomenon occurs in individual cells in many organs during the aging process, giving rise to a ‘tissue mosaic’ of a few isolated cells with mitochondrial dysfunction scattered amongst many normal cells.

Until recently it was not clear whether these few cells with defective mitochondria could be responsible for the loss of tissue and organ function associated with aging. Working in Prof. Rudolf Wiesner’s research team in Cologne, Dr. Olivier Baris and his co-workers looked at this tissue mosaic more closely in the context of cardiac arrhythmias.

Taking an experimental approach to the problem, the Cologne scientists used mice that express a mutated mitochondrial protein specifically in the heart as model organisms. The normal protein is required for proper mtDNA replication. In the clinic, the same mutation in patients leads to the accumulation of mtDNA deletions and severe neurological disease. Dr. Olivier Baris and his fellow scientists decided to investigate the heart because this organ is particularly dependent on mitochondrial energy production.

Dr. Baris: “The incidence of cardiac arrhythmias increases dramatically with age and contributes significantly to morbidity and mortality in the elderly.” Indeed, the mutated protein in the mouse heart was shown to cause the accumulation of mtDNA deletions and the development of a tissue mosaic.

Analysis of long-term electrocardiogram recordings in 18-month-old mice showed typical cardiac arrhythmias that are similar to those described in elderly people (spontaneous premature heart beats and blocks of the conduction of the electrical wave), and which intensify under stress. No such increase in arrhythmias was observed in 12-month-old mice that had three times fewer cells with mitochondrial dysfunction.

The results show promise for future new therapeutic approaches. As Dr. Baris concludes: “Our research has shown that the proportion of heart cells with impaired mitochondrial function has to exceed a threshold value in order to cause a functional disturbance of the organ.

A significant finding was that no other signs of cardiac dysfunction (increased scarring, dilatation of the heart or reduced pump function) were found in the mutated hearts.

We therefore showed that indeed the characteristic tendency towards arrhythmias in aging human hearts could be induced by the random accumulation of defective mitochondria in a few isolated cells and the resultant tissue mosaic.

The challenge of the future is to understand how altered mitochondrial function in just a few heart cells impacts the function of the entire organ. The scientists expect that it will be possible to develop new pharmacological treatment strategies for this aging-associated electrical conduction disorder in the heart – important new findings in aging research from CECAD.

Contact:
Dr. Olivier Baris
CECAD Cluster of Excellence
University of Cologne
Phone +49 221 478-7901
obaris@uni-koeln.de

Astrid Bergmeister MBA
Head of CECAD PR & Marketing
CECAD Cluster of Excellence
University of Cologne
Phone + 49 (0) 221-478 84043
astrid.bergmeister@uk-koeln.de

Weitere Informationen:

http://www.cecad.uni-koeln.de

Astrid Bergmeister | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

nachricht Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>