GLYCEROL CARBON CONTRIBUTES TO HEPATIC GLUCOSE-PRODUCTION DURING THE FIRST 8 HOURS IN HEALTHY TERM INFANTS

The newborn infant must mobilize endogenous substrate stores to meet t he requirements of glucose-dependent organs. High concentrations of fr ee fatty acids and glycerol, and a rapid decrease in the respiratory q uotient, indicate that lipids are an important fuel soon after birth. The purpose of the present study was to determine the onset of lipolys is and gluconeogenesis from glycerol in healthy, term, unfed infants. Eight infants were studied from a postnatal age of 3.5 +/- 0.5 h to 7. 4 +/- 0.2 h using [6,6-H-1(2)]glucose and [2-C-13]glycerol analysed by gas chromatography/mass spectrometry. Plasma concentrations of glucos e, glycerol and insulin averaged 2.9 +/- 0.4 mM, 369 +/- 89 mu M and 9 .4 +/- 3.7 mu U ml(-1), respectively. The hepatic glucose production r ate averaged 25.0 +/- 3.5 mu mol kg(-1) min(-1) (4.5 +/- 0.6 mg kg(-1) min(-1)) and the endogenous plasma appearance rate of glycerol 8.7 +/ - 1.2 mu mol kg(-1) min(-1). On average, 57.9 +/- 8.4% of the glycerol was converted to glucose, representing 11.1 +/- 2.3% of hepatic gluco se output. Thus, lipolysis and gluconeogenesis from glycerol are estab lished within the first 8 h of life in term infants.