Incorporation Rates of Palmitic (Pa) and Linoleic Acid (La)in Plasma Lipid Classes in Extremely Low Birth Weight Infants (Elbwi)

Background: Profound differences exist on the lipid and fatty acid (FA) composition of nutritional products fed/infused to newborn infants, however information on the metabolism of lipid classes and/or of individual FA in infants is very limited. We studied if PA and LA are incorporated differently into plasma lipids of ELBWI on the first day of life .Subjects: Six ELBWI (mean gestational age 28 weeks, range 27-29; mean weight 841, range 710-990) on IV glucose only (mean energy intake 27.3 kcal/kg/day, range 22.8-29.8).Interventions: During a 24 h infusion of albumin bound free U¹³C-PA and U¹³C-LA we measured the fractional synthesis rate (FSR) of plasma triglycerides (TG), phospholipids (PL) and cholesterol esters (CE) using both tracers as precursors. The isotopic enrichments of plasma free PA and LA (precursors) and of PA and LA in TG, PL and CE(products) were measured by GC-MS at t=0, 6.0, 12, 18 and 24h. FSR was calculated as follows: FSR = [ZB(t₂ - ZB (t₁)] _t1^t2 [ZA (t)- ZB (t)] dt where ZB and ZA are the tracer to tracee ration in precursor (A=FFA) and product (B=TG,PL,CE). Results: in% per hour (mean ± SEM), are reported below. Different superscripts indicate differences at p<0.05. Table

Table 1

Conclusion: The FSR of TG was higher than that of PL and CE. The incorporation rates of PA and LA into TG, PL and CE were similar. Under our study conditions no difference between PA and LA could be detected.