Acute hepatic ischaemia in the pig- the changes in plasma hormones, amino acids and brain biochemistry.

Acute hepatic ischaemia was induced in pigs by means of a portacaval shunt with hepatic artery ligation after 24 hours. Despite significant elevation in blood ammonia, fatty acids, aspartate aminotransferase, cerebrospinal fluid glutamine and ammonia, and brain tissue glutamine, ammonia and tryptophan, the experimental animals remained awake and alert and indistinguishable from sham-operated controls. The molar ratio of branched-chain to aromatic amino acids fell sharply in the arterial blood, but showed a terminal attempt at compensation in muscle venous samples. Portal and muscle venous insulin levels were elevated, and glucagon values rose in all circulation segments in the experimental group. The failure to induce coma in these pigs, despite the presence of many of the classical biochemical features, suggests that the syndrome of encephalopathy comprises several stages, and that the pig may be an important model in which to define these.