14 DAY TRIAL // The heart is the only organ inside the human body that can never be allowed to stop. Lungs do so from time to time, either on their own, or because we want them to, the brain disconnects itself occasionally too, especially during sleep, but the heart keeps soldering on without a moment's rest. Over the course of an average life time, it pumps more than 250 million liters of blood through the body and is also the main pump that does so. This means that its muscles need to be abnormally resistant and powerful. If they are not, then the heart fails and there is no way around this.
A group of scientists at the Heidelberg University Hospital, in Germany, has discovered a new protein, which they show plays a massive role in ensuring the durability of the most basic muscular unit of the human heart. This unit is called the sarcomere and is directly responsible for the heart's ability to function properly. The team, which also included members from National Genome Research Network (NGFN), the University of Lubeck, and the University of Munster, showed that mutations in the proteins caring for the sarcomere are the main cause for a new type of heart failure. The investigators report their finds in the November issue of respected scientific journal Nature Medicine.
Chronic heart failure, which is one of the most widespread conditions related to malfunctions of this organ, is in the vast majority of cases caused by dilated cardiomyopathy, which is the enlargement of the hearth's chambers, the atria and ventricles. These abnormalities are caused primarily by the fact that the heart looses its ability to pump blood at the required capacities. Its muscles are naturally to blame for this and, in some 20 percent of overall cases, the cause is genetic, the team reports. “In our studies of zebrafish, we discovered a protein that is needed to stabilize the Z-disk. If this protein (nexilin) is mutated, the movable muscle elements are no longer anchored firmly enough. The muscles then lose strength and the heart is weakened,” says Dr Tillman Dahme, a coauthor of the new paper.
“The nexilin dilated cardiomyopathy allowed us for the first time to describe a new form of heart muscle dilatation and define the mechanism causing it, namely destabilization of the Z-disk,” the expert adds. The research group was led by the HUH vice chair of the Department of Medicine III, Dr Wolfgang Rottbauer. “Patients with a nexilin mutation might benefit from early treatment with medications that reduce cardiac stress. This could lower the mechanical stress on the Z-disks and prevent progressive damage to the heart,” he concludes.