Metabolic Stress: Newly Found Cause of Heart Problems

Helen Holmes January 09, 2013

People who suffer from metabolic stress are at risk of atrial arrhythmias, a cardiovascular problem characterised by rapid heartbeat – scientists say.

Metabolic stress is a condition induced by poor oxygen supply in the cardiovascular system. While past studies have found that metabolic stress causes ventricular arrhythmias, this is the first time that such condition has been linked to the onset of arrhythmias in the atria – the upper chambers of the heart. The research, which was carried out by the British Heart Foundation in collaboration with Bristol University, may be used in the development of new therapies targeting such condition.

According to Dr Andrew James, the lead author, arrhythmias in the ventricles can be very dangerous and may result to ventricular fibrillation (severely abnormal heart rhythm), and death. Atrial arrhythmias, however, is not really fatal. Nevertheless, it is one of the major causes of stroke.

How does metabolic stress trigger heart disease?

In their report, which was published in the journal Circulation: Arrhythmia and Electrophysiology, Dr James and his colleagues explained how metabolic stress can stimulate the onset of atrial arrhythmia.

The human body has the special type of proteins known as the KATP channels which allow the cells to respond to changes induced by metabolism (the process by which the body converts nutrients we get from food into energy). During metabolism, a small molecule called adenosine triphosphate or ATP measures the ‘energy currency’ in the cells. There is an indirect relationship between the KATP proteins and ATP in such a way that when the ATP levels drop, the KATP channels are activated.

According to Dr James, KATP channels in the ventricles can be activated following metabolic stress triggered by the blockage of blood flow in a coronary artery. Such activation can protect heart muscles against the potential damage triggered by metabolic stress. However, this can disrupt the normal electrical activity in the heart, known as arrhythmias.

The study suggests that the drugs to be developed in treating atrial arrhythmias must target the atrial KATP channels.

Another important revelation in the study was that the blockade of the KATP channels induced by drugs used to treat type 2 diabetes completely reversed the effects of metabolic stress on the electrical activity of the atrium. However, such drugs do not have any effect in the absence of metabolic stress.

Researchers call for more investigations

Dr James said that further studies are needed to support their findings. Such studies should focus on whether differences between the properties of atrial, ventricular and pancreatic KATP channels exist so scientists can investigate the possibility of developing atrial-selective drugs.

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Source of this article:

Researchers identify new target for common heart condition