Final answer:
The MOA of the hepatic arterial buffer response involves the autoregulation of blood flow in the liver, with adenosine acting as a key mediator.
Step-by-step explanation:
The mechanism of action (MOA) of the hepatic arterial buffer response refers to the physiological regulation of the blood flow in the liver. The key player in this process is the autoregulation of the hepatic arterial blood flow. This means that when the portal venous pressure is low, the hepatic artery dilates to increase the flow and maintain a constant blood supply to the liver. Conversely, when portal venous pressure is high, the hepatic artery constricts. The primary site of the buffer response is at the level of pre-sinusoidal resistance vessels within the hepatic artery itself. Adenosine is often cited as a critical mediator involved in the signaling pathway that causes vasodilation within the hepatic artery during periods of reduced portal venous flow.