ORNITHINE-ALPHA-KETOGLUTARATE (OKG) SUPPLEMENTATION IS MORE EFFECTIVETHAN ITS COMPONENT SALTS IN TRAUMATIZED RATS

Addition of an anabolic stimulus during nutritional support seems to b e a reasonable adjunct to augment protein synthesis. Ornithine-alpha-k etoglutarate (OKG) has been used for this purpose in many pathological situations, but the mechanism of action is poorly understood. We have evaluated the relative metabolic efficacy of four isonitrogenous diet s with or without the addition of alpha-ketoglutarate (alpha KG) or or nithine (ORN), in a rat trauma (bilateral femur fracture) model. Both control and traumatized rats were starved for 2 d. Then for 4 d, the c ontrol rats were pair-fed to the traumatized rats, one of the four iso nitrogenous diets: the basal diet was a casein-based liquid diet; the ORN and OKG diets were the basal diet in which 10% of the dietary nitr ogen was replaced by ORN- or OKG-nitrogen, respectively; the alpha KG diet contained equivalent amounts of alpha KG as were present in the O KG diet. Body weight gain per gram of nitrogen intake was similar in a ll four diet groups of both control and traumatized rats. The fraction of nitrogen intake that was retained in the body was significantly hi gher in OKG-fed traumatized rats (23%) than in the corresponding basal diet-fed Fats. Plasma and muscle free amino acid concentrations were comparable in OKG- and ORN-fed rats but not in OKG- and alpha KG-fed r ats. Our data suggest that the mechanism of OKG action may be associat ed with increases in growth hormone and insulin, as well as the produc tion of metabolites of ORN and alpha KG. OKG has better metabolic bene fits than its two components given separately in the nutritional suppo rt of injured rats.