Daily rhythms in blood vessels may explain morning peak in heart attacks

Nov 10, 2008

It's not just the stress of going to work. Daily rhythms in the activity of cells that line blood vessels may help explain why heart attacks and strokes occur most often in early morning hours, researchers from Emory University School of Medicine have found.

Endothelial cells serve as the interface between the blood and the arteries, controlling arterial tone and helping to prevent clots that lead to strokes and heart attacks, says Ibhar Al Mheid, MD, a postdoctoral cardiology researcher at Emory.

He is scheduled to present his results in a poster session Monday, Nov. 10 at the American Heart Association Scientific Sessions in New Orleans.

"One of the important ways the lining of our blood vessels is maintained is by progenitor cells that come from the bone marrow," Al Mheid says. "These are essentially stem cells that help replace endothelial cells at sites of injury and build new vessels at sites deprived of adequate blood supply. The aim of our research was to look at the circadian pattern of both endothelial function -- the ability of blood vessels to relax -- and the abundance of the progenitor cells."

Working with Arshed Quyyumi, MD, professor of medicine and director of the Emory Cardiovascular Research Group, and colleagues, Al Mheid examined a dozen healthy middle-aged subjects every four hours for 24 hours. They drew blood while the subjects were asleep at 4 a.m. Blood vessel relaxation is assessed by cuff occlusion, a standard technique in measuring blood pressure – and was not measured at 4 a.m.

The researchers measured the ability of subjects' blood vessels to relax, the abundance of endothelial progenitor cells (EPCs) and their ability to grow in culture. Both the ability of blood vessels to relax and EPCs' ability to grow peaked (roughly 40 percent more than the middle of the day) at midnight, while cell numbers peaked at 8 p.m.

"The lining of our vessels appears to function better at night than in the day. Endothelial function is particularly depressed in the early morning hours," Al Mheid says.

He hypothesizes that an innate circadian timer in the brain, which other scientists have shown to be influenced by light and dark and daily activities, drives the cyclical variations in EPCs and endothelial function.

Source: Emory University

Explore further: Novel nanoparticle therapy promotes wound healing

add to favorites email to friend print save as pdf

Related Stories

Image: Human endothelial cells experiment bound for ISS

Feb 25, 2015

Components of human endothelial cells stained for identification. In red is the 'actin' protein that allows the cells to move, adhere, divide and react to stimuli. In blue are the cell nuclei containing DNA.

Building a better course starts with the syllabus

Mar 17, 2015

Recent award-winning research from the University of Virginia's Teaching Resource Center shows that tailoring teaching to how students learn improves courses and creates long-lasting impact.

Sweet nanoparticles target stroke

Mar 12, 2015

Materials resulting from chemical bonding of glucosamine, a type of sugar, with fullerenes, kind of nanoparticles known as buckyballs, might help to reduce cell damage and inflammation occurring after stroke. ...

Recommended for you

Novel nanoparticle therapy promotes wound healing

16 hours ago

An experimental therapy developed by researchers at Albert Einstein College of Medicine of Yeshiva University cut in half the time it takes to heal wounds compared to no treatment at all. Details of the therapy, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.