Blood vessels in the brain

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Endothelial cells lining the vessel are purple, red blood cells are red, and neurons are green.
Credit: Dan Mulkey

While neurons – nerve cells, shown in green in the image above – in the brain have been extensively studied, brain scientists have often relegated the brain’s blood vessels – outlined in purple above, and carrying small red blood cells – to second place.

New research indicates that these blood vessels may be quite specialised and unlike those in the rest of the body. Usually, a build-up of cellular waste products like carbon dioxide would cause a blood vessel to dilate, letting fresh blood come through to wash out the waste.

Things are different in the part of the brain that controls breathing, called the retrotrapezoid nucleus (RTN). Here, high levels of carbon dioxide are an important signal: they let the RTN know that the body really needs to breathe. If the blood vessels dilated in response to the carbon dioxide, that signal would be dissipated.

New research by Dan Mulkey and colleagues at the University of Connecticut, published in eLife, has found that the blood vessels in the RTN in fact constrict when carbon dioxide levels are high.

“This is a big change in how we think about breathing,” Mulkey says.

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