Effects of surgery on substrate metabolism in human adipose tissue

Abstract: Effects of Surgical Trauma on Substrate Metabolism in Human Adipose Tissue.Göran Felländer, Department of Surgery, Huddinge University Hospital, Karolinska Insdtutet, S-141 86 Huddinge, Sweden.The aim of this study was to characterize the effects of cholecystectomy onsubstrate metabolism in vivo and blood flow in adipose tissue usingmicrodialysis of the tissue interstitial compartment.One day after surgery, general insulin resistance and glucose intolerancedeveloped, there was no involvement of the glucose metabolism in adiposetissue. After the operation, the lipolytic activity in subcutaneous fat in situ wasinhibited in a normal fashion by infusion of glucose, indicating thatantilipolysis is not involved in the insulin resistance following a moderatelyserious surgical procedure.Subcutaneous adipose tissue liplolysis was activated by general anesthesia andabdominal surgery.The administration of glucose perioperatively caused afurther rise in lipolytic activity. The sympathetic nervous system mediated theincreased adipocyte lipolytic levels via noradrenaline release, and probablyinduced insulin resistance, thus overriding the antilipolytic effect ofhyperinsulinemia.Glucose uptake in adipose tissue, was reduced by the gallbladder operation.Lactate and pyruvate concentration of subcutaneous fat and plasma increased inresponse to surgery and exogenous glucose had little effect on the lactateproduction of adipose tissue but increased the pyruvate levels.The microdialysis ethanol clearance method provides a sensitve measure ofsmall physiological changes in adipose tissue blood flow. A comparison wasmade with the established 133Xe clearence technique to assess the adipose tissueblood flow. The experiments were carried out during basal conditions and inconjunction with vasodilation induced by external heating. A strongcorrelation was found between the two methods.The lipolytic activity during surgical trauma seems to be regulated by both B-and a-adrenergic mechanisms. There was a decrease in blood flow in the earlyphase of the study that could not explain the later changes in lipolytic activity.Microdialys may be a valuble method to study the metabolic response tosurgical trauma. This method can also be used to monitor the local blood flow.Until now adipose tissue has been studied, and the results show that this tissueis very important for the substrate metabolism during surgery.Key words: trauma, insulin resistance, free fatty acids, lactate, pyruvate,glucose, microdialysis, fat cells, catecholamines, cholecystectomy,anesthesia,133Xe clearance, adipose tissue blood flow, vasodilation.ISBN 91-628-1983-6