Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Overweight boys outweigh girls in stress response, study finds

06.11.2003


Overweight boys have greater increases in blood pressure in response to stress than their female peers and decreased ability to restore normal pressures, researchers say in the November issue of Hypertension.

A Medical College of Georgia study showed that, despite typically having a greater height/weight ratio, overweight girls’ blood pressures respond less to stress and their natural mechanisms for decreasing blood pressure work significantly better, said Dr. Gregory A. Harshfield, principal author.

"What we observed is that the boys had higher levels of blood pressure throughout, including during stress and recovery, but they did not show an equally greater level of sodium excretion to compensate for higher levels of blood pressure during stress," said Dr. Harshfield. "What we are showing is that the mechanisms driving salt-sensitive hypertension are having more impact in males than females," he said, noting that larger studies are needed before reaching any conclusions.



The body naturally responds to stress with an increase in blood pressure, by increasing blood vessel constriction as well as fluid volume inside vessels. The kidneys help with volume by holding onto sodium. Natriuresis is the body’s natural way of eliminating that sodium after the stress is gone to return blood pressure to pre-stress levels.

The study assessed the blood pressure levels of 151 boys and 141 girls ages 15 to 18 during and following stress using a protocol designed by Dr. Harshfield. Subjects were put on a diet for three days to normalize sodium levels. They then came to MCG’s Georgia Prevention Institute to participate in the protocol that includes two hours of rest, followed by an hour of playing challenging video games, followed by two more hours of rest.

Blood pressure and sodium excretion were measured throughout the five-hour period to determine how much blood pressure increased in response to stress and how quickly it returned to normal. Dr. Harshfield’s studies have found that black males particularly have a problem with pressure returning to normal because of reduced ability to eliminate sodium.

Dr. Harshfield recently obtained a $1.4 million National Institutes of Health grant to explore whether obesity contributes to a decrease in that natural sodium-reducing mechanism. He started seeing the sex differences as he was preparing data for that grant application.

"What we see when we use sex as a factor is that the relationship between adiposity and impaired pressure natriuresis is much more dominant in males than it is in females," Dr. Harshfield said. "The girls have more fat and yet, from our perspective, it’s causing less problems."

The MCG researchers believe the link between obesity and hypertension can be found in fat-produced leptin and angiotensinogen. Although leptin is likely better known for its role as an appetite suppressant, fat-produced leptin also stimulates the stress-trigged sympathetic nervous system. Fat also secretes angiotensinogen, which makes angiotensin II, a powerful vasoconstrictor. To make bad matters worse, leptin and angiotensin II also reduce sodium excretion.

One of the next steps is to determine why overweight girls seem less impacted. Dr. Harshfield theorizes that estrogen is likely the answer. "If estrogen increases nitric oxide and that increases vasodilation, that would blunt the increase in blood pressure in response to stress," he said. "The second thing estrogen does is reduce sympathetic nervous system tone so you don’t have as much vasoconstriction to begin with." Conversely, male sex hormones may augment blood pressure response, he said.

Toni Baker | EurekAlert!
Further information:
http://www.mcg.edu

More articles from Social Sciences:

nachricht Amazingly flexible: Learning to read in your thirties profoundly transforms the brain
26.05.2017 | Max-Planck-Institut für Kognitions- und Neurowissenschaften

nachricht Fixating on faces
26.01.2017 | California Institute of Technology

All articles from Social Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>