Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular defect found that may cause heart failure

20.09.2005


A new study has identified a molecular defect in cardiac cells that may be a fundamental cause of heart failure, a progressive weakening of the heart that leaves the organ unable to pump blood through the body.

The findings, by researchers at the Ohio State University Dorothy M. Davis Heart and Lung Research Institute, show that specialized proteins called ryanodine receptors (RyRs) malfunction in the failing heart. The RyRs form channels that become leaky, leading to calcium imbalances that prevent the heart from contracting effectively and relaxing adequately. The condition worsens until the heart can no longer work as a pump.

The root causes of heart failure are not known.



“We found some drastic changes in the way muscle cells in the failing heart handle calcium,” says principal investigator Sandor Gyorke, professor of physiology and cell biology at the OSU Davis Heart and Lung Research Institute. “Discovery of this mechanism suggests at least one potential target for treating the causes of this disease in a rational manner.”

Currently, the only way to correct heart failure is by heart transplantation.

About 4.9 million Americans are currently living with heart failure, and an estimated 265,000 of them die of it yearly. Those with the condition are at six to nine times greater risk of experiencing sudden cardiac death than someone in the general population. From 1992 to 2002, deaths from heart failure rose 35 percent and the incidence is expected to keep rising.

Calcium plays a fundamental role in muscle contraction, particularly in heart muscle. A heart contraction begins when the heart’s pacemaker sends an electrical signal to heart-muscle cells. The electrical signal triggers the release of calcium from a large storage site within each muscle cell. The released calcium activates the muscle cell’s contractile machinery, which causes the cell, and the heart as a whole, to contract.

This calcium storage site is known as the sarcoplasmic reticulum (SR), and it resembles a convoluted, flattened sack within the cell. The delicate, membrane-bound walls of the SR are penetrated with thousands of RyR channels. These serve as gate keepers that allow calcium to flood into the cell to initiate contraction.

The amount of calcium stored in the SR determines the strength of the heart beat and how much blood the heart ejects when it contracts.

At the end of a contraction, the channels close tightly. Molecular pumps, also located in the walls of the SR, then suck the released calcium back into the SR to prepare for the next contraction.

For this study, the OSU investigators used microscopic fluorescence imaging techniques to monitor changes in calcium ion concentrations in the SR and other regions of individual isolated heart cells.

They found that in heart failure, the channels cannot close tightly after a contraction. Instead, they remain partly open throughout the cardiac cycle. This allows some of the calcium to leak out.

This leaves too little calcium in the SR, so strong contrations are not possible, and too much calcium outside SR, so the muscle cells remain slightly contracted and the heart cannot fully relax.

As the condition worsens, the heart grows weaker as a pump.

Gyorke and his colleagues are now working to better understand the damage to the RyR channel.

Funding from the National Heart, Lung and Blood Institute; the American Heart Association; and the OSU Research Foundation supported this research.

Darrell E. Ward | EurekAlert!
Further information:
http://www.osu.edu

More articles from Life Sciences:

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Quantum material is promising 'ion conductor' for research, new technologies

17.08.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>