Free radicals, blamed for accelerating the aging processes and the development of various diseases, also fulfill many important functions in the body. Scientists from Sweden have shown that they regulate the heartbeat and increase its efficiency in a stressful situation.
As commented by the authors of the article in the Journal of Physiology, their research shows that excessive use of antioxidants that fight free radicals can do more harm than good.
Free radicals are formed in the body as a result of metabolic processes or under the influence of external factors, e.g. UV radiation. These molecules react very easily with other compounds and therefore can damage valuable cell components, such as fats or DNA.
On this basis, it was hypothesized many years ago that they accelerate the aging processes and the development of dangerous diseases, including the cardiovascular system, cancer and neurological diseases. It has contributed to the popularity of dietary supplements with antioxidants, i.e. compounds that fight free radicals, e.g. vitamins E and C.
However, research in recent years brings more and more discoveries indicating that free radicals are necessary for the functioning of various organs and the proper course of many physiological processes. For example, scientists from Israel have found in studies on mice that they have a beneficial effect on female fertility by stimulating ovulation. The information on this subject was published in the Proceedings of the National Academy of Sciences in January 2011.
Now, researchers at the Karolinska Institutet in Stockholm have shown that free radicals are signaling molecules that stimulate the heart to pump blood with adequate power, especially in a stressful situation.
As the researchers explain, under the influence of stress, the sympathetic nervous system activates beta-adrenergic receptors on the fibers of the heart muscle. This activates a whole cascade of biochemical processes, as a result of which the muscle fibers begin to contract more strongly and the heart beats with greater force.
Swedish scientists conducting experiments on the heart muscle cells (cardiomyocytes) of mice observed that stimulation of beta-adrenergic receptors also increased the production of free radicals in mitochondria, i.e. cell mini-power plants. Free radicals, in turn, intensified cardiomyocyte contractions.
When researchers exposed heart cells to antioxidants, their contractions, caused by stimulation of beta-adrenergic receptors, weakened.
This discovery reveals a new, hitherto unknown mechanism of regulating the power at which the heart works, and in the future it may also help to better understand the underlying causes of its various diseases, the authors of the study believe.
As commented by the researcher, Prof. Hakan Westerblad, under normal conditions, free radicals play many important functions in the body. Therefore, as with everything else, antioxidants should be used in moderation. Especially since the cells of our body have natural mechanisms of neutralizing free radicals, and antioxidants are also present in many components of a healthy diet, such as vegetables and fruits.
However, free radicals can contribute to the development of disease when they are excessively produced or if their high levels are sustained for too long. This is the case, for example, under conditions of chronic stress. It is known that long-term stress can lead to heart failure and various arrhythmias, and it may be suspected that the persistent high concentration of free radicals contributes in part to this, concludes Prof. Westerblad. (PAP)