Postheparin lipolytic activity and Intralipid clearance in very low-birth-weight infants

The effect of heparin (10 U/kg) on serum lipolytic activity, triglyceride and FFA levels, during four hours infusion of 0.5 gm/kg Intralipid was measured in 18 AGA infants, 25 to 32 weeks' gestational age. PHLA, TG, and FFA were measured at 0, 10, 30, 120, and 240 minutes of infusion of Intralipid, before and following a bolus of 10 U/kg heparin iv. Lipolytic activity, measured by hydrolysis of activated tri-3H-oleate and expressed in mumol FFA released per milliliter serum per hour, was not detected in serum before heparin administration. Ten minutes after heparin administration peak PHLA was significantly higher in infants of 27 to 32 weeks' gestation than in infants of 25 to 26 weeks' gestation. There was no significant difference in peak PHLA between infants of 27 to 28 and 29 to 32 weeks' gestation. PHLA returned to baseline (zero) two hours after heparin administration in all infants. Infants of 25 to 26 weeks' gestational age had significantly higher concentrations of serum triglycerides before and during Intralipid infusion than in infants of 27 to 32 weeks' gestational age. Although there was a transient rise in FFA 10 and 30 minutes after heparin administration, the levels of FFA and triglycerides were not different at the end of infusion with or without heparin in either group, suggesting that a single bolus of heparin has only a transient effect on Intralipid clearance.