VIRGINIA BEACH, VA (October 9, 2006) The theory that animals die when they've expended their lifetime allotment of energy may be reaching the end of its own life, according to a study presented at The American Physiological Society conference, Comparative Physiology 2006. However, the longitudinal study leaves open a newer form of the theory -- that antioxidants help prolong life by limiting the damage that oxidative stress can cause to cells.

"These findings join a growing body of evidence suggesting that lifetime energy expenditure per se does not underlie senescence," wrote Lobke Vaanholt, Serge Daan, Theodore Garland Jr. and G. Henk Visser in a summary of the study presented at Comparative Physiology 2006: Integrating Diversity. Vaanholt, Daan and Visser are from the University of Groningen, The Netherlands. Garland is from the University of California at Riverside. The conference takes place Oct. 8-11 in Virginia Beach, Virginia.

A bit of background: One early theory, the rate of living theory, held that every organism has a set amount of energy to expend. Once the animal expended that number of calories, the grim reaper was on the doorstep. Over the years, the theory has become much more sophisticated, but metabolic rate and aging have remained linked, Vaanholt explained.

Decades ago, physiologists discovered that during metabolism, oxygen (O2) can split into single oxygen atoms, known as free radicals. These rogue oxygen atoms can remain on their own or combine with hydrogen atoms to form reactive oxygen species (ROS), which wreak havoc with enzymes and proteins and adversely affect cell function. The faster the metabolism, the more ROS produced, the modern theory goes.

In this study the researchers divided the mice into three groups of 100 mice each. Two groups were "runner" mice, that is, mice that loved to run on the running wheels placed in their cages. One group of run
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Contact: Christine Guilfoy
cguilfoy@the-aps.org
301-634-7253
American Physiological Society
9-Oct-2006