ScienceDaily (Feb. 28, 2012) ? People with heart disease may not be able to compensate for their bodies' higher demand for oxygen when inhaling cold air, according to Penn State researchers, making snow shoveling and other activities dangerous for some.
"This study can help us understand why cold air is such a trigger for coronary events," said Lawrence I. Sinoway, Distinguished Professor of Medicine and director of the Heart and Vascular Institute, Penn State College of Medicine.
Breathing cold air during exercise can cause uneven oxygen distribution throughout the heart. But a healthy body generally corrects for this problem and redistributes blood flow, making sure the heart continues to function properly. In people with heart problems -- such as coronary artery disease -- this may not be the case, said Sinoway.
"If you are doing some type of isometric work and you're breathing cold air, your heart is doing more work -- it's consuming more oxygen," said Sinoway, also director of the Clinical and Translational Science Institute at Penn State.
Isometric work includes such activities as shoveling snow and carrying a briefcase or laptop bag. The heart works harder when exerted in cold temperatures and the number of deaths due to cardiac arrest peaks during the winter.
"There are two different things going on here -- demand and supply," said Matthew D. Muller, postdoctoral fellow at the Heart and Vascular Institute, Penn State College of Medicine. "We thought that oxygen demand in the heart would be higher with cold-air breathing and we also thought that oxygen supply would be a little bit impaired. And that's generally what we found."
Sinoway, Muller and colleagues reported their results in a recent issue of the Journal of Applied Physiology and in the current issue of the American Journal of Physiology, Heart and Circulatory Physiology.
The researchers first studied healthy young adults in their 20s and then studied a group of healthy older adults in their 60s so that they could learn how the heart functions in people without disease. Each subject was monitored for lung function and heart functions during the trials.
In order to measure heart function during exercise, the participants performed an isometric, or static, handgrip, which is a maneuver known to increase blood pressure. Subjects squeezed the handgrip device and held it still for two minutes, providing a consistent workload on the heart for the researchers to measure. Muller and Sinoway found that there was a supply-demand mismatch in the left ventricle -- where the heart receives oxygenated blood -- yet the heart was able to continue functioning appropriately.
These findings "suggest that healthy humans can adequately redistribute blood to the subendocardium (the blood vessels entering the heart) during the combined stimulus of cold-air inhalation and handgrip exercise," the researchers stated.
Also working on this research were Zhaohui Gao, instructor; Rachel C. Drew, postdoctoral fellow; Michael D. Herr, biomedical engineer; Urs A. Leuenberger, physician and professor of medicine; and Jessica L. Mast and Cheryl A. Blaha, clinical research nurses, all at the Heart and Vascular Institute, Penn State College of Medicine.
The National Institutes of Health and the Wilderness Medical Society both supported this research.
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The above story is reprinted from materials provided by Penn State.
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Journal Reference:
- M. D. Muller, Z. Gao, J. L. Mast, C. A. Blaha, R. C. Drew, U. A. Leuenberger, L. I. Sinoway. Aging attenuates the coronary blood flow response to cold air breathing and isometric handgrip in healthy humans. AJP: Heart and Circulatory Physiology, 2012; DOI: 10.1152/ajpheart.01195.2011
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.
Source: http://www.sciencedaily.com/releases/2012/02/120228123941.htm
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Welcome to ?Book Bits? for February 21, 2012. There?s a lot I could say about Stephen Colbert?s comments and questions for author and bookstore owner Ann Patchett on the Colbert Report. But really, there?s no need, for they speak for themselves. If you click on the link to listen to the interview, grab a glass of whiskey before putting on your earphones.
Interview: Adam Wilson (?Flatscreen?) with Brad Listi ? ?Raves Sam Lipsyte:? ?Adam Wilson is a gutsy, funny, and often beautiful writer, and Flatscreen is one of the most hilarious and commanding debuts I?ve read in a long time.?? ? Other People
Film: How to Prioritize Your Oscar Week Movie-Cramming, by Jason Bailey ? ?Flavorwire is offering, as a public service, a priority ranking of the nominees for the major awards (Picture, Director, Actor, Actress, Supporting Actor, Supporting Actress), so you can sift through the 18 nominees and see what time will permit you to see. Let?s be clear: this list is only tangentially related to the actual quality of the films at hand (since, as we?ve discussed, the Oscars often don?t reflect that quaint notion). ? ? Flavorwire
Review: The Book of Lost Fragrances by M.J. Rose ? ?Rose weaves Napoleonic history with that of China and the oppression of Tibet and then brings those ties even further back into history to Egypt and Cleopatra.? In addition to archeology, her characters delve into mythology, history, and hieroglyphics translation and more, creating an even denser and more mysterious novel than expected.? ? Savvy Verse & Wit
News: Gabby Giffords? husband to write children?s book ? ?Retired astronaut Mark Kelly, who collaborated with his wife, former U.S. Rep. Gabrielle Giffords, on her memoir, is writing a children?s book about a mouse that goes to space. ?On my first space shuttle flight, we had 18 mice on board as experiments,? Kelly said. ?And 17 of them, as soon as we got into zero gravity, stayed latched on to the side of the cage. But one of them seemed comfortable through the whole mission, like he was enjoying it.?? ? USA Today
Review: The Whipping Club, by Deborah Henry ? ?Inspired by her heritage and research of the Irish Industrial School system, Henry?s auspicious debut chronicles a couple?s attempt to save their son from horrific institutions.?? ? Kirkus Reviews
Review: Dancing with Memory: On Brian Castro?s Shanghai Dancing, reviewed by Colin Dickey ? ?Put simply, Shanghai Dancing is the best contemporary book in English that most Americans have never heard of. Castro?s ?fictional autobiography? follows Antonio Castro (whose biography shares much with Castro the author) ?forced to leave Shanghai as a child, he returns 40 years later seeking an inheritance consisting both of money and stories.? ? The Millions
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