Genetic Tweak Creates Super-Fit 'Mighty Mouse'

Look! On the treadmill! In the lab! It's 'Mighty Mouse'!

Researchers at Case Western Reserve University in Cleveland have created a race of genetically engineered super-mice.

The zippy rodents are more active, leaner and have more sexual stamina and longer lifespans than ordinary mice.

"They are metabolically similar to Lance Armstrong biking up the Pyrenees; they utilize mainly fatty acids for energy and produce very little lactic acid," senior researcher Richard W. Hanson said in a news release Wednesday.

• Click here to read the full news release.

On an inclined treadmill that slowly got faster and faster, ordinary mice were able to run about 19 minutes on average; the super-mice kept it up for an average of 31 minutes.

• Click here to see a video of the mouse race.

The genetically tweaked mice produce huge amounts of an enzyme called phosphoenolpyruvate carboxykinases, or PEPCK-C for short.

The overabundance of PEPCK-C radically changed the mice's metabolism, most remarkably in the relative lack of lactic acid, or lactate, in the blood after long periods of exercise. In ordinary mice, and in humans, lactic acid buildup rapidly leads to fatigue, cramps and sore muscles.

"At the beginning of exercise, the concentration of lactate was similar in two groups of mice, but by the end of the exercise period, the control group had elevated levels of blood lactate with little change in the levels in the PEPCK-C mice," the researchers said.

There is a downside, however. The ubermice eat 60 percent more food than their lumpen brethren, and are much more aggressive.

About 500 of the longer-lived, longer-breeding, voracious and tough mice have been produced.

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