Intravenous feeding of the rat with short chain fatty acid esters. II. Monoacetoacetin.

Acetoacetic acid is oxidized independent of carnitine transport into the cell mitochondria and its monoglyceride is a water soluble compound. The latter was examined as an intravenous nutrient. The monoglyceride of acetoacetic acid was prepared from the acid anhydride, diketene, and glycerol and was found to be totally miscible with water. The nutritional properties of monoacetoacetin were investigated by continuous intravenous infusion of 25 or 50 g/kg body weight per day into ad libitum fed rats. The response of these animals was compared to normal and food restricted rats. All experimental animals survived the 7 day study period in good health and were free of detectable physiological and behavioral abnormalities. The test rats demonstrated weight gain dependent on the infusion rate while on an inadequate spontaneous oral food intake diet. Ketonuria, hyperketonemia and monoglyceride excretion in the urine accompanied the infusion of monoacetoacetin and were dependent on the infusion load. At 50 g/kg per day total plasma ketones were found to be comparable with the infusion load. At 50 g/kg per day total plasma ketones were found to be comparable with the maximum level obtained in fasted rats, but the acetoacetate concentration was relatively higher than in fasting. This was consistant with ketosis derived from the hydrolysis of the monoglyceride. It was concluded from these results that monoacetoacetin might be an asset for intravenous nutrition.