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Hypertension: Free radicals responsible for high blood pressure

Hypertension: Free radicals responsible for high blood pressure


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How free radicals in the body raise blood pressure

Free radicals are highly reactive intermediates in our metabolism. They have long been suspected of having harmful effects on our bodies. A recent study now reveals that the metabolic intermediates raise blood pressure and damage the kidneys.

Researchers from the Medical College of Georgia at Augusta University showed in a study how hypertension causes immune cells to collect in the kidneys, where they emit more free radicals, which in turn increase blood pressure and cause damage to the kidneys. The results were recently published in the journal "Free Radical Biology and Medicine".

What are free radicals?

Free radicals are highly reactive chemicals that are produced as a by-product of oxygen processing in our body. Free radicals are also called reactive oxygen species, or ROS for short. The immune system uses these aggressive particles to kill intruders. In high concentrations, however, they are suspected of damaging the body and contributing to the development of numerous diseases.

From helper to inappropriate immune response

"It's a useful mechanism in our immune system, unless it's uncontrolled," said study author Dr. Justine M. Abais-Battad. With salt-sensitive hypertension, the free radicals are transformed by the helper into an inappropriate immune response, in which a high number of ROS favors inflammation, raises blood pressure and causes the kidneys to store more salt.

A high-salt diet leads to more free radicals

In experiments, the team showed that the number of free radicals in the kidneys was greatly increased in salt-sensitive rats. In a special group of rats, the researchers suppressed the so-called NADPH oxidase. This enzyme complex is a major producer of free radicals. In this group of rats, blood pressure did not rise when they were fed a high-salt diet.

The symptoms improved with a low-salt diet

When the researchers reactivated the ability to oxidize NADPH in the rats, they lost their protection against the high-salt diet. As a result, their blood pressure rose and they suffered kidney damage. After switching to a low-salt diet, the symptoms improved again.

Free radicals cause high blood pressure

"ROS, which is produced specifically by the immune cells, is sufficient to cause hypertension in these rats," emphasizes Abais-Battad. While this is a problem, it also shows a clear potential treatment option.

Why antioxidant therapies have so far failed

“If we understand how we can block the production of free radicals, especially in the kidney, there is a potential treatment,” adds head of research Dr. David L. Mattson. So far, antioxidant therapies have failed for many diseases because "they simply don't get to the right places," Mattson said. Knowledge of the cellular source of ROS is important to develop effective therapies.

The researchers came to the conclusion that "ROS from immune cells cause salt-sensitive hypertension and that targeted antioxidant therapies could have positive and protective effects."

What factors lead to increased free radical production?

A high-salt diet alone did not cause hypertension or an accumulation of immune cells in the kidneys in the rats. In addition, studies in humans, in which data on the causes of death were evaluated, showed that people with high blood pressure had more immune cells in their kidneys and had more kidney damage than people without high blood pressure.

The research team now wants to investigate more closely what leads to an increased production of free radicals. The first results suggest that the problem actually starts in the kidneys. The organ does not excrete salt sufficiently, the fluid level in the kidneys rises and thus the kidney pressure. The increased pressure in turn appears to attract ROS-producing immune cells.

Can a low-salt diet counteract this?

Research director Mattson believes it is good advice to reduce salt in the diet. However, in around half of the high blood pressure patients, the kidney is able to excrete excess salt. There is currently no way to distinguish these two groups from each other by simple tests.

Salt is not generally unhealthy

"We all have many types of salts in our bodies and we need them to keep water in our bodies," Mattson said. Excess salt consumption has only become a problem in the last 50 years.

Small problems can be alleviated by a low-salt diet

“With a low blood pressure increase, you can eat a low-salt diet, eat more potassium or fresh vegetables, and probably lower your blood pressure, too,” Mattson said. However, if the immune system is fully activated, it will likely no longer be enough.

Typical evildoers

The researchers point out that high amounts of salt are hidden in many dishes. Typical culprits are French fries, frozen meals, processed foods, canned vegetables, processed meat and sausages and sauces such as ketchup. (vb)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Graduate editor (FH) Volker Blasek

Swell:

  • Hypertension: Free radicals exposed as a cause of hypertension How free radicals in the body increase blood pressure Free radicals are highly reactive intermediates in our metabolism. A recent study now reveals that the metabolic intermediates raise blood pressure and damage the kidneys. Researchers from the Medical College of Georgia at Augusta University showed in a study how hypertension causes immune cells to collect in the kidneys, where they emit more free radicals, which in turn increase blood pressure and cause damage to the kidneys. The results were recently published in the journal "Free Radical Biology and Medicine". What are free radicals? Free radicals are highly reactive chemicals that are produced as a by-product of oxygen processing in our body. In high concentrations, however, they are suspected of damaging the body and contributing to the development of numerous diseases. From helper to inappropriate immune response "It is a useful mechanism of our immune system, unless it is uncontrolled," says study author Dr. With salt-sensitive hypertension, the free radicals from the helper to an inappropriate immune response, in which a high number of ROS promote inflammation, increase blood pressure and cause the kidneys to store more salt. A salt-rich diet leads to more free radicals. In experiments, the team showed that the number of free radicals in the kidneys was greatly increased in salt-sensitive rats. In a special group of rats, the researchers suppressed the so-called NADPH oxidase in the rats. In this group of rats, blood pressure did not rise when they were fed a high-salt diet. Symptoms improved with a low-salt diet When the researchers reactivated the ability of the rats to develop NADPH oxidase, they lost their protection against the high-salt diet. After switching to a low-salt diet, the symptoms improved again. Free radicals cause high blood pressure "ROS, which is produced specifically by the immune cells, is sufficient to cause high blood pressure in these rats," emphasizes Abais-Battad. Although this is a problem, it also shows a clear potential treatment option. Why antioxidant therapies so far "If we understand how we can block the production of free radicals, especially in the kidney, there is a potential treatment," adds head of research Dr. Dr. Knowledge of the cellular source of ROS is important in order to develop effective therapies Researchers come to the conclusion that "ROS from immune cells causes salt-sensitive hypertension and that targeted antioxidant therapies could have positive and protective effects." Which factors lead to increased production of free radicals? Immune cells in the kidney There were also studies in humans in which data on the causes of death were evaluated that people with high blood pressure had more immune cells in their kidneys and had more kidney damage than people without high blood pressure. The research team now wants to investigate exactly what exactly leads to an increased production of free radicals. The increased pressure in turn appears to attract ROS-producing immune cells. Can a low-salt diet counteract this? Research director Mattson believes it is good advice to reduce salt in the diet. There is currently no way to distinguish these two groups from each other by simple tests. Salt is not generally unhealthy "We all have many types of salts in our bodies and we need them to keep water in our bodies," said Mattson. Excess salt consumption has only become a problem in the last 50 years. Small problems can be alleviated by a low-salt diet "If the blood pressure rises slightly, you can eat a low-salt diet or eat more potassium or fresh vegetables and probably lower your blood pressure," advises Mattson. However, if the immune system is fully activated, it will likely no longer be enough. Typical culprits The researchers point out that high amounts of salt are hidden in many dishes. (vb) Hayley Lund, John Henry Dasinger, David L. Mattson, et al .: NOX2-derived reactive oxygen species in immune cells exacerbates salt-sensitive hypertension; in: Free Radical Biology and Medicine, 2020, sciencedirect.com
  • Augusta University: Free radicals from immune cells are direct cause of salt-sensitive hypertension (published: 02/11/2020), eurekalert.org


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