Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers show leaky muscle cells lead to fatigue

12.02.2008
What slows down marathoners may also tire heart failure patients; experimental drug that improves endurance may provide patients with relief from exhaustion

What do marathoners and heart failure patients have in common? More than you think according to new findings by physiologists at Columbia University Medical Center.

The new study shows that the fatigue that marathoners and other extreme athletes feel at the end of a race is caused by a tiny leak inside their muscles that probably also saps the energy from patients with heart failure.

The leak – which allows calcium to continuously leak inside muscle cells – weakens the force produced by the muscle and also turns on a protein-digesting enzyme that damages the muscle fibers. The new study found the leak was present in the muscle of mice after an intense three-week daily swimming regimen and in human athletes after three days of daily intense cycling. The same leak was previously discovered by Marks and colleagues in the muscles of animals with heart failure.

The new study also found that an experimental drug developed by the researchers alleviated muscle fatigue in mice after exercise, suggesting that the drug also may provide relief from the severe exhaustion that prevents patients with chronic heart failure from getting out of bed or fixing dinner.

The results will be published in the online edition of the Proceedings of the National Academy of Sciences at 5 p.m. ET on February 11, 2008.

“The study does not mean exercise is bad for you,” says the study’s senior author, Andrew Marks, M.D., chair of the Department of Physiology and Cellular Biophysics, and director of the Clyde and Helen Wu Center for Molecular Cardiology at Columbia University Medical Center. “We only saw the leak in animals and human athletes that exercised three hours a day at very high intensities for several days or weeks in a row until they were exhausted.” He notes that athletes’ muscles also will return to normal after several days of rest and any muscle damage will be repaired after several days or weeks depending on the degree of exercise.

However, the arm, leg and breathing muscles of patients with heart failure never have a chance to recover. “People with chronic heart failure are subject to this same kind of muscle leak and damage constantly even without doing any exercise,” Marks says. “One of these patients’ most debilitating symptoms is muscle weakness and fatigue, which can be so bad they can’t get out of bed, brush their teeth, or feed themselves.”

This fatigue experienced by heart failure patients does not stem from a reduction in the amount of blood and oxygen supplied to the muscles by the heart, as one might expect. Instead, Marks’ previous research in muscles of mice with heart failure suggested that fatigue in patients stems from the calcium leak, which reduced the ability of a single muscle to contract repeatedly before losing force.

“We then had a hunch that the process that produces fatigue in heart failure patients also may be responsible for the fatigue felt by athletes after a marathon or extreme training,” says the study’s first author, Andrew Bellinger, Ph.D., who is currently finishing his M.D. at Columbia University’s College of Physicians & Surgeons. “Our new paper shows that fatigue in both patients and athletes probably stems from the same leak.”

Fatigue Can Be Alleviated With Experimental Drug

The researchers then used the similarity between athletes and patients to their advantage to see if an experimental drug could increase exercise capacity and reduce fatigue.

The researchers gave the drug – which plugs the leak of calcium – to mice before the animals started a 3-week regimen of swimming. Without the drugs, mice are exhausted after three weeks of daily 3-hour swims. With the drug, the mice were still energetic, had lost less exercise capacity after 3 weeks, and their muscles showed fewer signs of calcium leakage, atrophy, and less muscle damage.

The cyclists in the current study were not given the drug, which is not yet available for people.

Plans are underway to test the drug at other medical centers in patients with heart failure to see if it relieves fatigue and improves heart function. Even if successful, it will take several years before the drug will be commercially available.

Study Also Provides Explanation for Muscle Fatigue Besides Lactic Acid

The calcium leak also provides a new explanation for the muscle soreness and fatigue that marathoners and other athletes can experience for weeks after crossing the finish line.

Physiologists have recently largely discarded the 100 year-old theory that lactic acid accumulation in the muscle cells produces fatigue and limits athletic performance. New theories have been exploring the role of calcium in this process. The involvement of defects in calcium handling in limiting muscle performance and producing exercise fatigue makes sense because the flow of calcium in and out of the muscle cell controls muscle contraction.

The discovery of the calcium leak in fatigued animals and athletes is the first time anyone has pinpointed a precise mechanism for the involvement of a defect in calcium handling in limiting exercise capacity.

Elizabeth Streich | EurekAlert!
Further information:
http://www.columbia.edu
http://www.cumc.columbia.edu

More articles from Studies and Analyses:

nachricht Graphene gives a tremendous boost to future terahertz cameras
16.04.2019 | ICFO-The Institute of Photonic Sciences

nachricht Mount Kilimanjaro: Ecosystems in Global Change
28.03.2019 | Julius-Maximilians-Universität Würzburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>