Effect of DL-3-hydroxybutyrate infusions on leucine and glucose kinetics in burned rats receiving TPN.

Whole-body leucine and plasma glucose kinetics were simultaneously measured in burned rats after 2 d of total parenteral nutrition (TPN) containing sodium DL-3-hydroxybutyrate or sodium acetate to evaluate the ketone bodies as energy substrates during stress. TPN solutions consisted of dextrose and amino acids [200 kcal/(kg . d); 13 g amino acids/(kg . d)] and contained 34.3 mEq/(kg . d) either as sodium DL-3-hydroxybutyrate (n = 8) or sodium acetate (n = 7). Whole-body leucine appearance, incorporation into protein, release from protein breakdown and oxidation rates, as measured after a constant infusion of L-[1-14C]leucine did not significantly differ between the groups. In contrast, D-[6-3H]glucose appearance rates after constant infusion of this tracer were significantly higher in rats given sodium DL-3-hydroxybutyrate [209.3 +/- 3.8 mumol/(kg body weight . min)] than in those given sodium acetate [162.4 +/- 9.7 mumol/(kg body weight . min)] (P less than 0.01). Since leucine kinetics did not differ, the results suggest that sodium DL-3-hydroxybutyrate infusions increase endogenous glucose production [61.0 +/- 4.6 mumol/(100 kg body weight . min)] by enhancing glucose recycling. However, there was no unique protein-sparing effect of ketone bodies identified during injury.