Influence of trauma on plasma elimination of exogenous fat and on lipoprotein lipase activity and mass

Abstract

Trauma is followed by an increased plasma clearance and oxidation of exogenous fat but the underlying mechanism is not fully understood. To examine the influence of a surgical trauma on the plasma elimination of exogenous triglycerides (TG) and its relationship with lipoprotein lipase (LPL) activity and LPL mass. Nine patients underwent a hypertriglyceridaemic clamp and a lipolytic capacity test before and after open abdominal surgery. The infusion rate was adjusted to maintain a stable TG concentration of 4 mmol x l(-1) during 180 min. The lipolytic capacity was determined as the change in LPL activity and mass following a bolus dose of 100 IU x kg BW(-1) heparin sodium. Postoperatively, the plasma elimination rate of fat was 2.6 times higher (P<0.001). Infusion of lipids in the postoperative state was followed by a smaller rise in free fatty acids (P<0.05) in comparison with the preoperative situation. The postoperative basal fasting LPL activity was half of that in the preoperative state and the LPL activity rose almost two-fold during the clamp. The heparin-induced rises in LPL activity and LPL mass were similar (n.s.) before and after surgery. A moderate surgical trauma is accompanied by a greater than two-fold rise in plasma elimination rate of exogenous fat despite a lower basal LPL activity and a virtually unchanged LPL pattern during infusion of lipids. Our study demonstrates that although trauma may substantially enhance the fat elimination capacity a significant proportion of the infused fat is not utilized for metabolic purposes.