H. Wei et al.
When the brain runs low on oxygen, red blood cells sense the deficit and hurl themselves through capillaries to deliver their cargo. That reaction, described online August 4 in Neuron, suggests that red blood cells can both detect and remedy low oxygen.
When researchers stimulated the feet of mice, nerve cells fired off signals in the corresponding part of the brain, depleting that area’s oxygen. Red blood cells in capillaries picked up their speed in response. And in artificial capillaries, the lower the oxygen, the faster the red blood cells moved, Jiandi Wan of the Rochester Institute of Technology in New York and colleagues found. That swiftness was caused by the cells becoming more flexible, a bendiness that let them squeeze through narrow capillaries faster. When researchers stiffened red blood cells with a chemical, the effect of low oxygen on speed disappeared.
The results reinforce the complex and important role of blood in the brain. The findings might ultimately be relevant for disorders in which the link between neural activity and blood flow is damaged, including Alzheimer’s disease, says study coauthor Maiken Nedergaard of the University of Rochester Medical Center.