February 3, 2009

Arteries adjust blood flow after stroke

U.S. medical researchers have discovered a grid of small arteries at the surface of the brain redirects and controls blood flow following a stroke.

University of California-San Diego scientists say they found the mesh-like network adjusts to restore normal supply when blood slows after a stroke.

This is optimistic news, said Professor David Kleinfeld, whose team studies blood flow in animal models of stroke.

Damage from stroke can continue for hours or even days as compromised brain tissue surrounding the core injury succumbs to deprivation of oxygen and nutrients, the researchers said.

This is the area doctors are trying to protect after a stroke, said Andy Shih, a postdoctoral fellow in Kleinfeld's group who conducted the experiments. Those neurons are teetering on the edge of death and survival.

The researchers said previous work found blood flow can persistently slow after a stroke, which would hinder the delivery of drugs that might help recovery. But, they said, those studies only measured the speed of the blood. By measuring both the speed of blood cells moving through individual small arteries and the diameters of the same vessels, the scientists found the arteries dilate to maintain a constant delivery of blood cells.

The research that included Patrick Drew, Philbert Tsai, Beth Friedman and Dr. Patrick Lyden appeared in the Jan. 28 online edition of the Journal of Cerebral Blood Flow and Metabolism.