Hepatic arterial pressure-flow autoregulation is adenosine mediated

Area of Science:

• Physiology
• Cardiovascular Research
• Hepatic Circulation

Background:

• Hepatic artery (HA) autoregulation is crucial for maintaining liver blood flow.
• The hepatic arterial buffer response (HABR) involves HA vasodilation in response to reduced portal flow.
• The role of adenosine in these processes has been investigated.

Purpose of the Study:

• To investigate the role of adenosine in hepatic artery (HA) pressure-flow autoregulation.
• To evaluate the effect of adenosine antagonists on HA autoregulation and the hepatic arterial buffer response (HABR).
• To elucidate the underlying mechanism of HA autoregulation and HABR.

Main Methods:

• Quantifying pressure-flow autoregulation in the feline HA.
• Administering selective adenosine antagonists (8-phenyltheophylline and 8-(p-sulfophenyl)theophylline).
• Evaluating vasodilator responses to exogenous adenosine and the HABR.

Main Results:

• Weak pressure-flow autoregulation was observed in the HA of cats.
• Adenosine antagonists inhibited both HA autoregulation and the vasodilator response to adenosine.
• These antagonists also inhibited the HABR.

Conclusions:

• The findings suggest that local adenosine levels influence HA pressure-flow autoregulation.
• The mechanism of HABR is proposed to involve adenosine washout into portal blood.
• HA pressure-flow autoregulation and HABR likely share a common mechanism involving adenosine washout.