Not just for the skin
Application of sunscreen
According to a new study presented at the American conference "Experimental Biology 2019" by a group of scientists from the University of Pennsylvania, sunscreen can benefit in addition to protecting against skin cancer.
It has long been known that ultraviolet radiation (UVR) is the main causal factor of skin cancer.
Exposure to ultraviolet rays causes damage at the cellular and molecular levels, which contributes to skin aging.
These are well-known facts for a long time, so the latest study examines the relationship between UVR and the work of skin blood vessels.
Early studies have shown that solar radiation affects the blood vessels of the skin. In particular, it reduces the level of vasodilation (vasodilation), the mediator of which is nitric oxide (NO).
Nitric oxide is an important signaling molecule. In addition to other functions, NO acts as a vasodilator: it participates in the relaxation of the smooth muscles of blood vessels, thereby increasing blood supply.
NO and vasodilation
The blood supply to the skin plays a vital role, allowing the body to maintain temperature and respond to heat stress. If the body overheats, nitric oxide provokes vasodilation, which increases blood flow and, consequently, heat transfer.
Almost every cell type is capable of producing nitric oxide, but this process requires a substance called 5-methyltetrahydrofolate (5-MTHF). Experts believe that UVR reduces the level of 5-MTHF, which is present in the skin, thereby limiting vasodilation.
As the authors of the study write: "NO-conditioned vasodilation is a "marker of skin vascular health"."
The effects of nitric oxide can extend beyond the skin. Some researchers have concluded that vasodilation in the skin may have a general effect on blood pressure.
Recently, a group of scientists decided to investigate how the use of sunscreen can affect the relationship between ultraviolet radiation and vasodilation. They compared the process of NO-conditioned vasodilation of the skin, which they covered with sunscreen or sweat.
For the study, the researchers recruited 13 healthy participants with light and medium skin tone. They exposed one hand of each subject to ultraviolet radiation, while the other hand served as a control. The team calculated UVR exposure equivalent to 1 hour outside on a sunny day.
Each participant passed three parallel tests on an irradiated arm: UVR only, UVR with sunscreen and UVR with sweat.
As expected, compared to the control arm, there was a decrease in NO-caused vasodilation at the irradiated site without protection. In other words, ultraviolet radiation prevented nitric oxide from initiating muscle relaxation in blood vessels, thereby reducing the body's ability to cool down.
Conversely, both the areas with sunscreen and the areas with sweat did not show a decrease in NO-caused vasodilation.
The authors write: "UVR may actually increase NO-caused vasodilation in the presence of sunscreen with chemical filters. For those who spend a lot of time working, exercising or participating in other outdoor activities, the use of sunscreen will help protect not only from skin cancer, but also from a decrease in the function of skin vessels."
It is important to note that this was a small-scale study that was not peer-reviewed. In addition, it is worth mentioning that although nitric oxide is the main regulator of vascular tone, other mechanisms also play a role in this function.
Since only changes in NO-conditioned vasodilation were evaluated in this experiment, further work will be required to understand whether other mechanisms affect the interaction with protective creams and the sun.
However, the researchers are not trying to reverse the current recommendations. Regardless of whether other studies repeat their findings, the use of sunscreen is still as important as ever.
Elena Panasyuk, portal "Eternal youth" http://vechnayamolodost.ru / based on the materials of MedicalNewsToday: Sunscreen may help maintain blood vessel health