Background: During fasting and catabolic states free fatty acids (FFA) are released from the breakdown of AT triglycerides. Lipolysis has been measured in humans with stable isotopes using labeled PA or glycerol as traces. No information is available on the rate of appearance (Ra) of LA. Subjects: 7 infants (age 57.4±64 days(range 1-149), weight 3.6±1.3 kg (mean±SD)) admitted to the Pediatric or Neonatal Intensive Care Units for sepsis syndrome and receiving IV glucose only (energy intake of 20±5.4 kcal·kg-1·day1).Interventions: We measured simultaneously the Ra of PA and LA during a constant intravenous infusion of albumin bound U13C-PA and U13C-LA. Blood was drawn at baseline, 1:50, 2:0, and 2:10 hours from the start of the infusion and the isotopic enrichments of plasma free PA and LA determined by GC-MS (SIM mode). A percutaneous AT biopsy was obtained before the isotope infusion. Results: Main results are reported below: Table AT·PA was higher than AT·LA.#p<0.001. The Ra of PA was higher than that of LA,§ p=0.005 However, the ratio of the Ra's to the respective mol% values of the FA in AT was higher for LA than for PA, *p=0.02. The Ra of LA correlated with LA in AT (y=0.28x-0.14 r=0.96 p<0.01).Conclusion :: LA is preferentially released during lipolysis in comparison with PA. Further studies should investigate if PA and LA are metabolized and/or oxidized differently in infants with sepsis.

Table 1
Full size table