Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers reveal calcium transport protein function that regulates heartbeat frequency, strength

05.02.2004


A membrane protein, NCX1, that transports sodium and calcium into and out of cells, may determine the frequency as well as strength of the heartbeat, researchers at UT Southwestern Medical Center at Dallas report.



The findings are published in today’s issue of Nature.

"This calcium transporter really is an important key to understanding how the heart is regulated," said Dr. Donald Hilgemann, professor of physiology and senior author of the study. "At every beat, calcium in heart cells increases. And it’s calcium that is the messenger to the heart to get it to contract.


"We knew for a long time that NCX1 brings calcium into and out of heart cells by exchanging it for sodium. And in doing so it generates important electrical currents in the heart. The surprise is that this transporter dances more than just that old waltz from Vienna. It knows Salsa!"

The research reveals two new modes of operation of NCX1. First, the membrane protein can move sodium into heart cells without moving calcium out. This mode generates an electrical current independent of calcium transport that contributes to excitation of the heart. The second mode is to move calcium into heart cells without generating any electrical current. This mode, Dr. Hilgemann said, may determine the calcium that remains in heart cells after each beat and thereby determines the strength of cardiac contraction over many beats.

Using so-called "giant membrane patch" techniques together with highly sensitive ion detection techniques, both developed and implemented by Dr. Hilgemann, UT Southwestern researchers were able to determine precisely how NCX1 works as an ion exchanger, how many calcium and sodium ions move across the membrane, when they are exchanged, and, surprisingly, when they move together.

"Transporters move ions across membranes by grabbing hold of them and transferring the energy of one type of ion to another type, just one or a few at a time, backwards and forward, together or in exchange for one another," Dr. Hilgemann said. "This is a much bigger biophysical problem to get a handle on than ion channels. Ion channels, when they are open, let millions of ions slip through them each second. You measure the electrical current, and you know what’s going on."

UT Southwestern researchers over the last three years spearheaded new approaches to measure ion transfer across microscopic patches of membrane, independent of the electrical current. The "giant patch" system is essentially a large piece of cell membrane glued to the end of a glass pipette. This method has been used by numerous groups to study ion transporters and channels that could not be studied with conventional techniques. It can measure the properties of these systems in a millionth of a second, at least 10 times faster than the previous methods.

"Seeing now that NCX1, in some instances, moves an extra calcium or an extra sodium ion lets us predict much better how this system works in the heart and how it affects the function of the heart," Dr. Hilgemann said. "There are many, many more important transporters – many of them involved in human disease – to be studied with this kind of resolution in the kidney, in the pancreas, in the brain, everywhere. NCX1 is just the tip of the iceberg."


In 1997 Dr. Hilgemann was named Young Investigator of the Year by the International Biophysical Society in recognition of his studies of transport systems that move molecules across cell membranes.

Dr. Tong Mook Kang, a former fellow at UT Southwestern who is now at the Sungkyunkwan University School of Medicine in South Korea, is coauthor of the study.

The research was funded by the National Institutes of Health and the Samsung Biomedical Research Institute.

To automatically receive news releases from UT Southwestern via e-mail, subscribe at http://www.utsouthwestern.edu/utsw/cda/dept37326/files/37813.html

Amy Shields | EurekAlert!
Further information:
http://www.swmed.edu/

More articles from Life Sciences:

nachricht Machine learning, imaging technique may boost colon cancer diagnosis
06.12.2019 | Washington University in St. Louis

nachricht The 136 Million Atom-Model: Scientists Simulate Photosynthesis
06.12.2019 | Jacobs University Bremen gGmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Engineers at Duke University have developed a microscope that adapts its lighting angles, colors and patterns while teaching itself the optimal...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Lights on fishing nets save turtles and dolphins

06.12.2019 | Ecology, The Environment and Conservation

Machine learning, imaging technique may boost colon cancer diagnosis

06.12.2019 | Life Sciences

'Virtual biopsy' allows doctors to accurately diagnose precancerous pancreatic cysts

06.12.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>