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Hepatic artery buffer response

The liver has a dual blood supply with 50% of its oxygen supply coming from the hepatic artery and the other 50% coming from the portal vein. One way the liver ensures proper oxygenated blood delivery is through an intrinsic response known as the hepatic arterial buffer response (HABR).

The HABR is activated in response to low portal vein flow by increasing hepatic artery flow, or in response to decreased hepatic artery flow by increasing portal vein flow. In terms of physiology, this occurs because low portal vein flows lead to a build up of adenosine in the periportal regions causing hepatic artery dilation. When portal venous flow increases, it washes out any build-up of adenosine, resulting in vasoconstriction and a decrease in hepatic arterial flow.

The HABR compensation is limited with a maximum doubling of hepatic arterial flow. The buffer response is diminished in the presence of other disorders, such as endotoxinemia and splanchnic hypoperfusion. A failing HABR can lead to hypoxic liver injury.