Carbohydrate three-carbon metabolism of adipose tissue during surgery

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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 −1 · h −1). 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.