| Abstract: | To evaluate the effect of the glucose-induced insulin release on peripheral substrate metabolism, we studied muscle metabolism in seven patients after elective surgery and in four healthy volunteers combining the forearm and the euglycemic glucose clamp technique (insulin infusion, 0.2 mU/kg per minute). Arterial and deep venous concentrations of substrates and hormones were determined in the basal period and during steady state of the infusion period. After 90 minutes of insulin infusion, the whole-body glucose infusion rate was significantly lower in patients who had elective surgery, although plasma insulin concentrations were comparable. In both groups this was related to a reduced supply of free fatty acids and ketones in muscle. In controls the resulting lack of substrates in muscle appeared to be compensated by an enhanced uptake of glucose, not seen in the patients who had elective surgery. Surprisingly, as indicated by the significantly reduced lactate production (-0.15 +/- 0.05 vs -0.62 +/- 0.32 mumol/100 g per minute basal), in this group the glucose taken up was oxidized aerobically to a greater extent. However, the total resulting energy gain was small. Thus, a peripheral energy deficit might arise favoring increased oxidation of amino acids. To avoid this undesired side effect, only those substrates should be administered that minimize pancreatic insulin release. |
