Teams of scientists at Washington University School of Medicine in St. Louis have identified a mechanism that triggers increased blood flow to brain cells actively engaged in work. The findings appear in two papers in the Jan. 13 issue of the Proceedings of the National Academy of Sciences (PNAS) and are available online.

The researchers are hoping to apply the new insights to improve understanding of basic brain function and limit side effects of diabetes, but the new insights could have much wider ramifications.

"One can pick out any number of diseases where knowing how increased blood flow in the brain is activated will be very important and useful," says Marcus E. Raichle, M.D., professor of radiology, neurology and of anatomy and neurobiology. "Changes in blood circulation in the brain are linked, for example, to Alzheimer's disease as well as stroke."

Scientists have known since the late 1800s that when a muscle cell contracts repeatedly or a nerve cell increases its activity, the circulatory system responds by increasing blood flow to the activated cells. They assumed this happens so the blood can supply the cells with more sugar and oxygen as fuel for the increased workload.

Over the past decade, a growing body of evidence has suggested that this idea, logical as it seems, is incorrect. The new Washington University studies, one conducted in animals and the other in humans, give scientists a sense for how blood flow increases in the context of cellular exertion. Why blood flow increases still remains elusive, but knowing how the increase is triggered will provide vital aid to answering that question.

Raichle, who led the human study in PNAS, also directed a 1988 study that found increased brain activity increased blood flow much more than brain cells' consumption
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Contact: Michael C. Purdy
purdym@msnotes.wustl.edu
314-286-0122
Washington University School of Medicine
7-Jan-2004