How calcium ions control muscle power

The penetration of calcium ions, which cause muscle cells to contract, is visible under a TIRF microscope. This innovative microscope, funded by the Swiss National Science Foundation (SNSF), sheds unique light on what sets healthy muscles apart from diseased ones.

Calcium ions play a crucial role in muscle cells. When the ions accumulate, they indicate there is work to be done to the muscle cells and that they should therefore contract. As a result, it comes as no surprise that disorders in the calcium balance of muscle cells are the root causes of different muscle diseases.

If the calcium ions exceed a critical concentration, in the case of heat stroke (or in medical terminology: malign hyperthermia) for instance, they trigger an uncontrolled muscle reaction that may be fatal. Because muscle cells develop heat and finally die off if they remain active for too long a period.

Calcium ions penetrate the cell interior via two routes: they are either released inside from the muscle cells' storage chambers or penetrate the cell envelope from outside.

Susan Treves of the Biomedicine Department at the University of Basel examines what goes on around the cell envelope with the help of an innovative device, the TIRF microscope (TIRF stands for Total Internal Reflection Fluorescence). The microscope exploits the fact that light beams, shed at an angle, are totally reflected on optical interfaces. The light beam is therefore captured in the glass slide and only the cell envelope in direct contact with the slide is illuminated.

Consequently, Susan Treves has proved that more calcium ions penetrate the muscle cells of patients with muscle diseases from outside than the muscle cells of healthy persons. Besides the different release from the storage chambers, the changed flow of calcium ions through the cell envelope is now therefore also considered as a potential cause of muscle diseases.

As a result, these diseases appear to have several triggers. These findings do push the prospect of discovering a single drug to cure all muscle diseases into the distant future, but nevertheless a more exact appreciation of the calcium balance of muscle cells aims to help as many patients as possible some day.

Contact
Dr. Susan Treves
Biomedicine Department
University Hospital of Basel
Hebelstrasse 20
4031 Basel
Tel.: +41 61 265 23 73
Email: susan.treves@unibas.ch