APPLIED NUTRITIONAL INVESTIGATION Nutririon Vol. 12, No. 9, 1996 Carbohydrate Three-Carbon Metabolism of Adipose Tissue During Surgery GijRAN FELL;iNDER, MD, PHD,* JAN BOLINDER, MD, PHD,” * URBAN UNGERSTEDT, MD, PHD,I_ PETER ARNER, MD, PHD,” * INGA TJiiDER, MD,* AND JijRGEN NORDENSTROM, MD, PHD* From the Departments of *Surgery, * *Medicine, $Anesthesiology and Clinical Research Center, Huddinge University Hospital, Huddinge and fDepartment of Pharmacology, Karolinska Institute, Stockholm, Sweden Date accepted: 29 January 1996 ABSTRACT Carbohydrate metabolites were continuously measured in the extracellular space of adipose tissue with microdialysis in 24 patients during elective cholecystectomy. The metabolism of exogenously supplied glucose by adipose tissue was assessed by measuring changes in glucose, pyruvate, and lactate in this tissue and making comparisons with changes in the levels of these metabolites in blood. Twelve patients were randomized to receive glucose infusion (50 mg/mL, 216 mL/h) and another 12 patients to receive saline infusion (9 mg/mL, 3 mL* kg-‘* h-l). The surgical trauma caused a typical stress response, including increased plasma catecholamine levels, hyperglycemia, and hyperinsulinemia. The relative increases in glucose during surgery were greater in plasma than in the adipose tissue of patients receiving glucose. The concentrations of lactate in the dialysate were similar in the glucose and saline groups. During surgery, the concentrations of pyruvate in blood and dialysate increased in the group receiving glucose. At the end of surgery, a higher than normal lactate to pyruvate (L:P) ratio in plasma was observed in blood (L:P = 18) but not in subcutaneous fat (L:P = 12). The origin of this increased level of lactate relative to pyruvate in the circulation is not known, but evidently it does not come from the subcutaneous fat. In conclusion, surgical trauma caused a typical stress response including increased plasma catecholamine levels, hyperglycemia, and hyperinsulinemia. Glucose uptake in adipose tissue, as indicated by the ratio of adipose tissue to plasma glucose, was reduced by trauma. Lactate concentrations in subcutaneous fat and plasma increased in response to surgery, and exogenous glucose, given in amounts corresponding to energy expenditure, had little effect on the lactate concentrations in plasma and in adipose tissue. Nutn’tion 1996; 12:589-594 Key words: glucose, lactate, pyruvate, trauma, microdialysis INTRODUCTION Accidental or elective trauma is associated with pronounced alterations in the carbohydrate metabolism. These changes in- clude hyperglycemia accompanied by hyperinsulinemia, ’ in- creased gluconeogenesis,’ and a shift in whole-body oxidation from glucose to fat.3 Traditionally, the interest in changes in the lactate and pyruvate levels of injured patients concerns the use of these levels as indicators of poor tissue perfusion and anerobic metabolism. During such conditions, plasma lactate levels may increase severalfold. The glycolytic 3-carbon metab- olites lactate and pyruvate, however, are also increased in trauma, even without concomitant anerobic metabolism.4.5 The capacity of adipose tissue to convert glucose to lactate in vivo has been documented.6-9 Studies by M&in et al.6 have shown that, after an overnight fast, adipose tissue takes up approximately 10% of a 100-g oral glucose load, of which about 60-80% is converted to and released as lactate. Lactate formed in peripheral tissues may be synthesized to glycogen in the liver via the glycogenic (Cori) pathway.” Although the contribution of lactate originating from adipose tissue to whole- body gluconeogenesis was believed to be relatively small, more recent studies have shown that the quantitative contribution of adipose tissue under certain conditions may be about lo- 30%.6,” The importance of lactate as a gluconeogenetic precur- Supported by grant 19X-01034 from the Swedish Medical Research Council and grants from the Swedish Diabetes Association, the Karolinska Institute, and the Nordic Insulin Foundation. Correspondence to: Dr Gbran Fellander, Department of Surgery, Huddinge University Hospital, S-141 86 Huddinge, Sweden Nutrition 12:589-594, 1996 OElsevier Science Inc. 1996 Printed in the USA. All rights reserved. ELSEVIER 0899-9007/96/$15.00 PII: SO899-9007(96)00175-X