ATP and 2,3-diphosphoglycerate changes in the erythrocytes of hyperammonaemic sheep

The experiment was conducted on sheep receiving NH4Cl infusions into v. mesentericta anterior. During first 3 h animals received ammonia in a dose of 13 mumol X min-1 X kg body wt.-1 and then next 3 h in a dose of 30 mumol X min-1 X kg body wt.-1. When ammonia was administered in smaller doses its concentration increased to 0.65 and 0.22 mmol/l in portal and peripheral blood, respectively. Simultaneous slight increase of ATP and marked of 2,3-diphosphoglycerate (2,3-DPG) was observed. These effects of moderate ammonia loading are probably caused by the rise of glucose utilization in erythrocytes. Ammonia given in a higher dose induced further rise of its concentration to 1.1 and 0.51 mmol/l in portal and peripheral blood, respectively. Such NH4Cl infusion caused a further rise of 2,3-DPG concentration connected with the drop of ATP level in ovine red blood cells. It seems that a decrease of ATP level was mainly the result of local high 2,3-DPG level which inhibits glycolytic enzymes.