Postnatal age and the metabolism of medium- and long-chain fatty acids by isolated hepatocytes from small-for-gestational-age and appropriate-for-gestational-age piglets.

Hepatocytes were isolated from full-term small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) piglets at 6 or 48 h postpartum and incubated with 1 mmol/L [1-14C]-octanoate (8:0), -nonanoate (9:0) or -oleate (18:1). The cells oxidized [nmol 1-C/(h.10(6) cells)] 9:0 to carbon dioxide (12.5) and acid soluble products (28.9) faster than 8:0 (10.9, 20.6, respectively), and both were oxidized faster than 18:1 (3.9, 9.9) regardless of the piglet age or weight. Oleate accumulated in lipid products eightfold faster than did 8:0 and 9:0. No differences between cells from SGA and AGA piglets were detected. Recovery of 1-C in CO2 was 48% higher in incubations with cells from 48-h-old than from 6-h-old piglets. This increase was attributable to a 70% higher O2 consumption by 48-h-old cells. Theoretical O2 consumption rates were computed from the fatty acid flux data and compared with measured O2 consumption. Hepatocytes from SGA and AGA piglets were equally capable of satisfying greater than 75% of their energy needs from fatty acid oxidation. The O2 consumption attributable to 9:0 metabolism was 30% higher than observed for 8:0 and 18:1. All fatty acids apparently spared endogenous fuels to a greater degree in 6-h-old than in 48-h-old piglets.