Researchers say a pill may someday replace sweaty workouts for the health conscious

<br>WASHINGTON (AP) _ Pop a pill, get in shape. <br><br>That ultimate fantasy of the couch potato may become a reality some day, according to researchers who have found the chemical pathways muscle cells

Thursday, April 11th 2002, 12:00 am

By: News On 6

WASHINGTON (AP) _ Pop a pill, get in shape.

That ultimate fantasy of the couch potato may become a reality some day, according to researchers who have found the chemical pathways muscle cells use to build strength and endurance.

With this basic knowledge in hand, it now may 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 and senior author of a study appearing Friday in the journal Science.

Does this mean sedentary people could build muscle by taking pills?

``That may be one of the possibilities,'' said Williams, but the main target of the research is to promote the health of people with heart disease or other conditions that keep them from doing enough exercise.

``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 help patients with heart or lung disease, or lower the risk of Type II diabetes, 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 colleagues at the University of Texas Southwestern Medical Center in Dallas created a group of mice with genes that made a surplus of a protein called calmodulin-dependent protein kinase, or CaMK. When this protein is activated, it and another protein, calcineurin, trigger the physical changes that muscle cells undergo after intense exercise.

Williams said mice with a high level of CaMK 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 that required by marathon runners.

For ``fast twitch'' muscles, which provide a burst of strength for a short period of time, there was an increase in the number of mitochondria.

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 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 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.