The meeting which took place in Rome on November 19th and 20th of 1982 is easily the best meeting on hepatic coma that I have ever attended, and I have attended many. It was an exceedingly we- planned meeting with prolonged opportunity for discussion, and there was genuine interplay and exchange of ideas (not the usual picture of a rushed meeting with investigators presenting their own point of view and talking past each other without a meaningful ex­ change) which took place in Rome. My co-editors and I hope that the published transcript, which of course can only reflect what transpired in Rome on those two days, does justice to a very intellectually exciting and gratifying ex­ change of ideas. L. Capocaccia, J. E. Fischer and F. Rossi-Fanelli v CONTENTS Introduction 1 SECTION 1: PATHOGENETIC PROBLEMS IN HEPATIC ENCEPHALOPATHY Ammonia: The old and the new • • . • • • . • . • • • . • . • 5 L. Zieve Role of synergism in the pathogenesis of hepatic encephalopathy • • • • . • • . . . . • 15 L. Zieve y-Aminobutyric acid receptors in experimental hepatic encephalopathy •. •. • • 25 M. L. Zeneroli, <. Baraldi,and E. Ventura A possible role for excitatory neurotoxic amino acids in the pathogenesis of hepatic en­ 41 cephalopathy • • • • • • • • • • • • • • • F. Moroni, G. Lombardi, G. Moneti, D. Pellegrini and C.