Abstract
The aim of this study was to characterize the effects of cholecystectomy on substrate metabolism in vivo and blood flow in adipose tissue using microdialysis of the tissue interstitial compartment. One day after surgery, general insulin resistance and glucose intolerance developed, there was no involvement of the glucose metabolism in adipose tissue. After the operation, the lipolytic activity in subcutaneous fat in situ was inhibited in a normal fashion by infusion of glucose, indicating that antilipolysis is not involved in the insulin resistance following a moderately serious surgical procedure. Subcutaneous adipose tissue liplolysis was activated by general anesthesia and abdominal surgery. The administration of glucose perioperatively caused a further rise in lipolytic activity.
The sympathetic nervous system mediated the increased adipocyte lipolytic levels via noradrenaline release, and probably induced insulin resistance, thus overriding the antilipolytic effect of hyperinsulinemia. Glucose uptake in adipose tissue, was reduced by the gallbladder operation. Lactate and pyruvate concentration of subcutaneous fat and plasma increased in response to surgery and exogenous glucose had little effect on the lactate production of adipose tissue but increased the pyruvate levels. The microdialysis ethanol clearance method provides a sensitive measure of small physiological changes in adipose tissue blood flow. A comparison was made with the established 133Xe clearance technique to assess the adipose tissue blood flow. The experiments were carried out during basal conditions and in conjunction with vasodilation induced by external heating.
A strong correlation 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 early phase of the study that could not explain the later changes in lipolytic activity. Microdialysis may be a valuable method to study the metabolic response to surgical 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 tissue is very important for the substrate metabolism during surgery.
