“…However, when ammonia was infused in an amount resulting most likely in a slight peripheral hyperammonemia there was observed initially a fall, then an increase, in the hepatic blood supply (P < 0.05, Table 2). The increased inflow of ammonia via the portal vein can suggest its locally sympathetic-like vasoconstrictor influence (BAREJ et al, 1980). Alternatively, the inverse situation of a forcible extension of hepatic efficiency to remove ammonia may have provoked a rise in the portal and hepatic blood flow, probably due to the depressive effect of ammonia on the vasomotor centres in the central nervous system (SCHENKER, 1967;WALKER and SCHENKER, 1970).…”