Plasma amino acid clearance as an indicator of hepatic function and high-energy phosphate in hepatic ischemia

A major junction of the liver is to maintain normal levels of plasma amino acids. This function may depend in part on tissue levels of high-energy phosphate. Experiments were performed in adult mongrel dogs to assess the relationship between plasma amino acid clearance (PAAC) and tissue high-energy phosphate after 90 minutes of warm hepatic ischemia. In addition, when PAAC was assessed in the anhepatic dog, PAAC fell to low levels after hepatectomy. After 90 minutes of warm ischemia, both tissue adenosine triphosphate (ATP) and PAAC fell to low levels, with PAAC similar to those levels observed in anhepatic dogs. Recovery of ATP and PAAC progressed over a 48-hour period but did not reach control values. Mortality rate was 33% in a group of 12 animals at 48 hours after ischemia. At 24 hours after ischemia, total free plasma ammino acid levels were significantly higher in those animals that were dying as compared with those that were surviving (4352 μmol/L versus 2850 μmol/L; p < 0.05). There was a strong correlation between PAAC and ATP (r = 0.81). PAAC appears to be an indicator of hepatic functional recovery and tissue ATP levels after ischemia.