Free fatty acid kinetics after burn shock in guinea pigs

Extensive full-skin-thickness burn results in a change in the flux and utilization of the major metabolic fuels. Considerable work has been done on glucose metabolism after severe burn, but much less is known about free fatty acid (FFA) metabolism. Therefore, we studied the rate of appearance (Ra), the rate of disappearance (Rd), the metabolic clearance rate (MCR), and the plasma FFA concentration 0--6 hours after a 50% body surface area full-skin-thickness burn using a constant infusion of 14C-palmitate. We found that the plasma FFA concentration decreased from a control value of 0.60 +/- 0.05 microns/ml to 0.26 +/- 0.04 microns/ml of plasma at 2 hours postburn (P less than 0.05). This change appears to be due to a greater decrease in Ra than Rd. The MCR was unchanged during this period (26.7 ml/kg . min). In a second series of experiments, the plasma FFA concentration, Ra and Rd at 5.5--6 hours postburn did not differ from the preburn values. The rapid decline of plasma FFA 0--30 minutes postburn may relate to decreased blood flow to adipose tissue, which in the same guinea pig model had decreased about 80% at 15 minutes postburn, or to a shift toward esterification in the fat depots, decreasing FFA mobilization.