Ridecamp: [RC] Bioengineered Endurance Athletes?

Is the horse of the future a transgenic beast? <g>

Scientists create 'endurance' mouse

May lead to wonder drug for distance athletes
By Kate Tobin
CNN Sci-Tech

BOSTON, Massachusetts (CNN) --Mighty Mouse lives, and the "new age" 
version is downright buff.

Researchers say they have created a transgenic mouse with muscles 
like a marathoner, capable of enduring rigorous exercise for extended 
periods of time.

While so far the research has only been conducted on mice, scientists 
say they expect the techniques they've developed to treat the mouse 
muscle will also work on humans. Doctors say the discovery may one 
day lead to new treatments for people who are bedridden or have 
degenerative muscle disease, and could prove to be a wonder drug for 
endurance athletes like long distance runners or cross country skiers.

Bruce Spiegelman and colleagues at the Dana-Farber Cancer Institute 
identified a biochemical called PGC-1 that operates as a molecular 
switch, converting so-called "fast-twitch" muscle, which is strong 
but tires quickly, into high-endurance "slow-twitch" muscle.

"PGC-1 appears to be the switch, or a major component of it, that 
enables your body's muscles to adjust to the demands being put on 
them," said Spiegelman. "Understanding how this system works could 
make it possible to develop a drug to manipulate this system."

Muscle is made up of a combination of different types of fibers. 
Endurance athletes train long and hard to build up slow-twitch muscle 
fibers, called Type I fibers, which are long and lean and can keep 
pumping for long periods of aerobic exercise. Sprinters or 
weightlifters, on the other hand, have muscle rich in fast-twitch, 
Type II fibers. These muscles are bulkier and stronger but tire 
quickly.

Further studies

To create the endurance mouse, Spiegelman's group bioengineered PGC-1 
into mouse muscle tissue. They expected that it would promote the 
development of cellular power plants called mitochondria, which fuel 
the growth and development of slow-twitch muscle fiber. But they were 
surprised to find that PGC-1 appeared to be converting Type II 
fast-twitch fibers into Type I slow-twitch fibers.

The muscle itself actually changed color, taking on a reddish hue 
characteristic of oxygen-rich tissue. Further, in an endurance test 
at a Texas laboratory, the bioengineered muscle turned out to 
contract efficiently two and a half times longer than regular muscle.

Spiegelman cautions that there is still five to 10 years of work to 
be done before PGC-1 based treatments will be available.

The research is published in this week's edition of the journal Nature.

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