Posted on 04/10/2002 5:36:36 PM PDT by ATOMIC_PUNK
Scientists ID New Form of Exercise
Scientists Identify Way of Strengthening Muscle Cells Without Lots of Exercise
W A S H I N G T O N, April 10 —
It's a couch potato's dream: Instead of sweating and straining, people someday may simply pop a pill to get in shape, say researchers who have identified how muscle cells get stronger from regular exercise.
Researchers at Duke University and the University of Texas Southwestern Medical Center have found the chemical pathway that muscle cells use to build up their strength and endurance.
With this basic knowledge in hand, it may now be possible to develop a pill that pumps up muscle cells without all that exercise, said Dr. R. Sanders Williams, dean of the Duke University of School of Medicine.
"That may be one of the possibilities," said Williams.
But, as a physician, Williams said he the main target of the research is to help people with heart disease or other conditions that keep them from doing enough exercise to remain healthy.
"This could lead to drugs that will let people get the health benefits of regular exercise, even if they cannot exercise," said Williams. This could improve the health of patients with heart or lung disease, or lower the risk of diabetes II, for instance.
"It is possible it could become a drug of abuse because it would enhance the performance of athletes," he said.
In the study, Williams and his colleagues created a group of mice with genes that over-expressed a signaling protein called calmodulin-dependent protein kinase, or CaMK. When this signaling protein is activated, it and another protein, calcineurin, trigger the physical changes that muscle cells undergo after intense exercise.
Williams said that mice with a high level of CaMK expression developed more mitochondria in muscle cells and saw an increase of a type of cell called the "slow twitch" muscle. These are muscle cells that power sustained activity, such as required by marathon runners.
The researchers found that mice with high levels of CaMK developed the same healthy muscle cells as mice that did exercise.
"The effect increases more of the slow twitch muscles, but it also increases the number of mitochondia in the fast twitch muscle cells," he said. "That is very similar to what happens in very intense training."
Mitochondria are structures inside a cell that provide energy by metabolizing oxygen and nutrition. Cells with many mitochondria can produce more work over a longer time. Physical training increases the number of mitochondria in muscle cells.
Williams said that a drug that would trigger the CaMK muscle signaling pathway has not been found, but now that there is a specific target it should made the development easier.
"Pharmaceutical companies are very good at that," he said.
Dr. Keshav Singh of Johns Hopkins University School of Medicine said that the paper by Williams and his group is an "important advancement in understanding the mechanism that creates more mitochondria in muscles."
"Since levels of mitochondrial proteins decrease with normal aging, this study may also help develop therapies to increase the physical endurance in the aged," said Singh, who is a mitochondria researcher at Hopkins.
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