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 New technique for in-cell distance determination
19.03.2019 | Universität Konstanz

nachricht Dalian Coherent Light Source reveals hydroxyl super rotors from water photochemistry
19.03.2019 | Chinese Academy of Sciences Headquarters

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

Im Focus: Sensing shakes

A new way to sense earthquakes could help improve early warning systems

Every year earthquakes worldwide claim hundreds or even thousands of lives. Forewarning allows people to head for safety and a matter of seconds could spell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Levitating objects with light

19.03.2019 | Physics and Astronomy

New technique for in-cell distance determination

19.03.2019 | Life Sciences

Stellar cartography

19.03.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>