Brain energy reserve, tricarboxylic cycle intermediate and some putative neurotransmitters were measured in a devascularisation model with portacaval shunt and hepatic artery ligation done in two interventions. Conditions were standardized in that physiologic parameters, i.e. body temperature, systemic arterial pressure, PO2, PCO2 and pH, were kept constant and brain tissue was obtained with the "freeze-blowing" technique designed for deep freezing brain substance in less than one second. 1. Measured values indicative of the brain energy reserve (glucose, glycogen, ATP and phosphocreatin) were not found to differ from those of sham-operated animals. 2. Of the stimulating neurotransmitters, norepinephrine, dopamine, glutamic acid and aspartic acids were reduced with the exception of acetylcholine among the inhibitory neurotransmitters GABA and cAMP were unchanged, while all others including serotonin, octopamine, and phenylethanolamine were increased. 3. The results of these experiments suggest that an inbalance of amino acids with resultant changes in neurotransmitter profiles rather than an energy deficit constitutes the factor underlying hepatic coma.