0.105 OXIDATION RATE OF 13C-LABELED MEDIUM CHAIN TRIGLYCERIDES ADMINISTERED ENTERALLY OR PARENTERALLY Metaes,C.; Wolfram, G.; Schmidt, H.-L. Lehrstuhl fur Ernahrungslehre und Lehrstuhl fur Allgemeine Chemie und Biochemie der Technischen Universitat Milnchen in Weihenstephan Medium chain triglycerides (MCT) are a useful source of energy due to their special biochemical behaviour. After oral application they are more rapidly hydrclyzed, absorbed and oxidized than long chain triglycerides (LCT). Recently MCT have also been used in fat emulsions for parenteral nutrition. Our topic was the comparison of the rate of oxidation of MCT administered enterally or parenterally. To healthy subjects after an overnight fast a formula diet was given with 17 energy % protein, 58 % carbohydrates and 23 % sunflower oil for 8 hours in an amount of 100 kcal/hr. 1 hour after the start of the experiment 100 mg 13C la- beled #CT (trioctanoate 99-Atom% 13C in the carboxyl groups) in 10 ml MCT/LCT fat emulsion (Lipofundin MCT 10%) was applied as a bolus within 3 min to the same subjects enterally and one week later under the same nutrition conditions parenterally. The 13C-excess in the breath CO2 was determined from one hour before till 6 hours after application by isotope ratio mass spectrometry. Maximal 13CO2 exhalation was reached after ca. 45 min with both ways of admini- stration. The total rate of oxidation of 13C-MCT within 6 hours was higher than the oxidation rate of 13C-linoleic acid-T in previous experiments. In contrast to LCT oxidation between both ways of application only small differences of 13C-MCT oxidation rates were found. Control experiments with supplying only formula diet showed no influence on a constant normal 13CO2 exhalation.

Our results indicate that in the case of MCT oxidation the kind of administration in artificial nutrition does only make a schmall difference. It is therefore supposed that parenterally administered MCT are also oxidized by extrahepatic tissues.

0.106 THE EFFECTS OF AN ENTERALLY-FED STRUCTURED LIPID EMULSION ON PROTEIN METABOLISM IN THE BURNED RAT M.Iwasa, K..T.Hamawy, Y.Iwasa, V.K.Babayan, B.R.Bistrian, G.L. Blackburn (Nutrition/Metabolism Lab. New England Deaconess Hospital/Harvard Medical School, Boston, MA., U.S.A. )

Fat emulsions are often used to partially meet energy requirements during total enteral nutrition (TEN). This study was designed to evaluate the effects of a chemically stru- ctured triglyceride(Captex 710A) emulsion in comparison to other lipid sources. 37 male SD rats weighing 2DO-25Dg underwent gastric catheterization and received a full thicness scald bum (25% of body surface). Animals were then randomized to receive one of 4 isonitrogenous (2g N/kgBW/day), isocaloric (200 kcal/kgBW/day) TEN regimens for 72 hours. 50% of NPC were as fat: Groupl-710A, GroupZ-LCT and Group3-MCT. Group4 served as a dextrose only control. Following TEN, all animals were given a bolus injection of 3H-leucine (50 uCi/lOOgBW) via a lateral tail vein and fractional synthetic rates in liver, muscle and whole body were determined after 10 minutes.

Cumulative ISR (%/day)

1: N balance(g) Liver Muscle Whole body

710A 0.72f0.2 103.OtiO.6* 20.9*5.0* 23.7f6.3* LCT 9 1.19fo.l**## 144.3rt19.3**#6 21.4f5.0* 20.2zt4.9* MCT 9 1.33*0.3**## 129.4&29.1**// 23.7&6.9* 19.9iz6.1 Cont. 9 0.66&0.2 81.9& 8.3 16.Oti.8 14.8zKJ.7 M+SD, *:p<o.o5, **:p<O.Ol vs Cont. t:p<0.05, t#:p<O.Ol vs 710A.

These results suggest that partial replacement of NPC with fat emulsions, particularly LCT, improves N balance and FSR. The unique advantages of parenterally administered structured lipid was not evident with enteral feeding.

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