Mice living in the high-altitude, oxygen-starved environment of the Andean mountains survive those harsh conditions by fueling their muscles with carbohydrates. The findings, reported online on December 6 in Current Biology, a Cell Press publication, provide the first compelling evidence of a clear difference in energy metabolism between high- and low-altitude native mammals.
"The high-altitude mice we examined in this study are a rare exception to a general exercise fuel use pattern seen in lowland mammals," said Marie-Pierre Schippers of McMaster University. "Studying exceptions to a rule is often the key to uncovering the mechanisms of a physiological process."
The new study conducted with collaborators from the Universidad Peruana Cayetano Heredia in Peru could therefore lead to increased understanding not only of mountain-dwelling mice but also of other mammals, including humans, said Grant McClelland, also of McMaster University.
At an altitude of roughly 4,000 meters, every breath of air contains about 40 percent less oxygen than it would at sea level. Under those conditions, carbohydrates are the logical energy source. That's because carbs can supply 15 percent more energy for the same amount of oxygen in comparison to fats.
In fact, the idea that high-altitude environments should favor carbohydrate metabolism was proposed almost 30 years ago, but it hadn't really been put to the test. In the new study, the researchers used a powerful multispecies approach, using four native species of mice, two from the Peruvian Andes and two found at sea level.
The researchers found that the high-altitude mice do indeed burn more carbohydrates. Their heart muscles show greater oxidative capacity, too, both adaptations that would afford the animals the ability to remain active at altitude more successfully than their lowland relatives could.
Those differences aren't a matter of adjusting to high versus low altitude but are rather due to inherent differences in the mice that have apparently arisen more than once over the course of evolutionary time.
"This is one of 'nature's solutions' to low atmospheric oxygen," McClelland said. "Our study shows that Andean mouse species have independently evolved a metabolic strategy that maximizes energy yield when little oxygen is available. It is possible that a similar strategy has also evolved in other high-altitude mammals, including humans."
Schippers et al.: "Increase in Carbohydrate Utilization in High-Altitude Andean Mice."
Cell Press: http://www.cellpress.com
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Mother deer rushed towards the infant distress calls of seals, humans and even bats, suggesting that these mammals share similar emotions
In the forests of eastern Australia, a squadron of social spiders faces off against an army of the world's most dangerous ants in a pitched battle for survival
Contrary to some earlier projections, the world's population will soar through the end of the 21st century thanks largely to sub-Saharan Africa's higher-than-expected birth rates, United Nations and other population experts said on Thursday.
Archaeologists got to the root of an ancient hairstyle when they unearthed a 3,300-year-old body with 70 hair extensions
A major international study finds that killings among chimpanzees result from normal competition, not human interference.
Clownfish travel hundreds of kilometres, but it is the larvae rather than the adults that migrate
U.S. government researchers working with divers and sonar equipment have located the wrecks of what they dubbed "forgotten ghost ships" in waters just outside San Francisco's Golden Gate strait.
"It's spooky," a Clearwater, Fla., fisherman said, comparing the toxic algae bloom to "boiled red Georgia clay"
Physicist Danielle Bassett has been awarded a MacArthur Fellowship based on her work studying the human brain. She talks with Melissa Block about the advances it may lead to.
A team of researchers are using multispectral imaging to uncover hidden text on a 1491 Martellus map, one of the most important maps in history. Lead researcher Chet Van Duzer thinks the discoveries will allow historians and scholars to see just how the map influenced cartography in its time.