Total Parenteral Feeding of Rats with an Acetoacetate Monoglyceride and Glucose Mixture

Total parenteral nutrition (TPN) by means of monoacetoacetin (glycerol monoacetoacetate) was compared with TPN by using glucose-glycerol. Growth and urinary nitrogen, copper and zinc over 7 d and leucine dynamics on the last day were studied. Complete intravenous diets were administered to five groups of rats which were differentiated by receiving 45 kcal/d (group A) or 65 kcal/d (group C) from a 50% glucose-50% glycerol mixture, 45 kcal/d (group B) or 65 kcal/d (group D) from a 67% monoacetoacetin-33% glucose mixture, or 45 kcal/d (group E) from 100% monoacetoacetin. Leucine kinetics were determined by continuous infusion. Animals from groups A and C were hyperglycemic and normoketonemic, groups B and D were normoglycemic and hyperketonemic, and group E tended to be normoglycemic and hyperketonemic. Group B rats gained weight and retained the most nitrogen while groups A and E lost weight and groups C and D maintained their weight. Nitrogen losses correlated with weight changes. Urinary copper and zinc were not increased by giving ketone bodies. Leucine kinetics were found to be low for group C compared to its energy-matched group, and leucine metabolism was not correlated with nitrogen output and growth. The data suggest that a monoacetoacetin-glucose mixture is preferable as a nonprotein energy source for TPN when compared to either substance alone.