Abstract
Lipoprotein lipase hydrolyzes triglycerides in plasma and thus regulates the clearance of fat from the circulation. Liproprotein lipase activity has been estimated in infants during parenteral nutrition by measuring postheparin lipolytic activity (PHLA). PHLA is, however, an inadequate measure of lipoprotein lipase because a substantial part of PHLA results from hepatic lipase. Carnitine is essential for facilitated transport of long-chain fatty acids across the mitochondrial membrane. With specific methods we measured lipoprotein and hepatic lipase activities. Nine newborn infants were operated on because of gastrointestinal anomalies. Parenteral nutrition was built up in three days whereafter infants received 3/g/kg/day of fat (intralipid) at a constant rate. On the average, weight gain started at the age of 5 days and was 16 g/day. The duration of parenteral nutrition was 1-23 weeks. During the first week lipoprotein lipase activity increased from 14 to 35 μmol FFA/ml/h whereas hepatic lipase activity remained at 40 μmol FFA/ml/h during parenteral nutrition. Serum free carnitine decreased from 25 to 11 μmol/1 and acylcarnitine from 9 to 2 μmol/1 during the first three weeks of parenteral nutrition; urinary excretion of carnitine decreased from 114 to 68 nmol/mg of creatinine. Serum triglycerides, free fatty acids and blood beta-hydroxybutyrate remained, however, practically unchanged during parenteral nutrition. The results suggest that neither lipoprotein lipase activity nor carnitine availability are rate-limiting for the utilization of fat in newborn infants during parenteral nutrition.
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Rovamo, L., Nikkila, E. & Raivio, K. Postheparin plasma lipoprotein and hepatic lipases and serum camitine in newborn infants during parenteral nutrition. Pediatr Res 18, 797 (1984). https://doi.org/10.1203/00006450-198408000-00033
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DOI: https://doi.org/10.1203/00006450-198408000-00033