Study offers new insights into the mechanics of muscle fatigue

January 17, 2013

A study in The Journal of General Physiology examines the consequences of muscle activity with surprising results, indicating that the extracellular accumulation of potassium that occurs in working muscles is considerably higher than previously thought.

Muscle excitation involves the influx of and efflux of . Although the fraction of ions that cross the muscle membrane with each contraction is minute, repeated activity can lead to substantial changes in the intracellular and extracellular concentrations of sodium and potassium ions. The extent of these changes, however, has been unclear. Now, Torben Clausen from Aarhus University in Denmark provides quantitative analyses of the changes in intracellular and extracellular ion concentration resulting from stimulation of a leg muscle in rats, providing insight into how they vary with muscle activity.

Clausen measured the changes in concentration of sodium, potassium, and in working rat extensor digitorum longus (ESL) muscles. Remarkably, when their muscles were stimulated to fire at a rate of 5 Hz (comparable to that in the legs of a person riding a bicycle) for five minutes, sufficient intracellular potassium was lost to lead to an extracellular concentration that would interfere with further excitation. These results suggest that accumulation of extracellular potassium is a much larger contributor to than previously thought, which may be of particular importance in such conditions as hyperkalemic and other channelopathies that affect skeletal muscle. These changes in ion distribution are opposed through the action of the "Na+/K+ pump"—which expends energy to move sodium out of the cell and potassium into it—and will therefore be even more pronounced under disease- and injury-related conditions associated with decreased pump activity.

Explore further: Neuroscientists' discovery could bring relief to epilepsy sufferers

More information: Clausen, T., et al. 2013. J. Gen. Physiol. doi:10.1085/jgp.201210892

Related Stories

Study finds new pathway critical to heart arrhythmia

October 26, 2011

University of Maryland School of Medicine researchers have uncovered a previously unknown molecular pathway that is critical to understanding cardiac arrhythmia and other heart muscle problems. Understanding the basic science ...

Recommended for you

Artificial beta cells

December 8, 2016

Researchers led by ETH Professor Martin Fussenegger at the Department of Biosystems Science and Engineering (D-BSSE) in Basel have produced artificial beta cells using a straightforward engineering approach.

Key regulator of bone development identified

December 8, 2016

Loss of a key protein leads to defects in skeletal development including reduced bone density and a shortening of the fingers and toes—a condition known as brachydactyly. The discovery was made by researchers at Penn State ...

Researchers question lifelong immunity to toxoplasmosis

December 8, 2016

Medical students are taught that once infected with Toxoplasma gondii—the "cat parasite"—then you're protected from reinfection for the rest of your life. This dogma should be questioned, argue researchers in an Opinion ...

TET proteins drive early neurogenesis

December 7, 2016

The fate of stem cells is determined by series of choices that sequentially narrow their available options until stem cells' offspring have found their station and purpose in the body. Their decisions are guided in part by ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.