BETHESDA, MD (August 25, 2006) Cooling water temperature during the fall prompts the crucian carp to store vast amounts of glycogen in its brain to keep the brain functioning and healthy from February to April, when there is no oxygen left in the ponds, a new study finds.

The study from Finland found that the amount of glycogen in the brain was at its peak in February, when the pond becomes nearly depleted of oxygen (anoxic). Glycogen, an energy supply that the carp brain uses to survive anoxia, was 15 times higher in February, compared to brain glycogen content in July, when oxygen in the pond is at its peak.

At the same time, the carp brain's sodium-potassium pump activity, a measure of energy demand, decreased 10-fold to its low point between February and April, said the study's lead author, Vesa Paajanen. Taken together, these findings indicate the carp extends the amount of time it can survive without oxygen in frigid water by 150-fold. Further, the study found that it was the dropping water temperature that sets these physiological changes into motion.

"This is the first study to show that sodium pump activity is controlled by water temperature, not by the amount of oxygen available in the water" Paajanen said. The findings help explain how the carp pulls off the remarkable physiological feat that allows its brain to survive for months in a nearly anoxic state.

There is currently no direct tie between these finding and humans. However, physiologists only recently realized the human brain contains glycogen, so who knows? Maybe this line of research will one day be important for humans to survive anoxia, Paajanen said.

The study, "Seasonal changes in glycogen content and Na-K-ATPase activity in the brain of the crucian carp," by Matti Vornanen and Vesa Paajanen of the University of Joensuu in Joensuu, Finland appears in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. Th
'"/>

Contact: Christine Guilfoy
cguilfoy@the-aps.org
301-634-7253
American Physiological Society
25-Aug-2006