Plasma levels of catecholamines and lipolysis during starvation in growingpigs

The aim of this study was to clarify the triggering mechanism of lipolysis in adipose tissue during feed withdrawal in pigs. Evaluation of blood sampl es drawn via an intravenous catheter from 10 growing pigs fasted for 60 h d emonstrated, in addition to a haemodilution, a significant rise in plasma l evels of non-esterified fatty acids (250 +/- 37 to 1427 +/- 144 mu mol/l) a nd free glycerol (98 +/- 27 to 232 +/- 41 mu mol/l) within 48 h of feed res triction, and thereafter the concentrations levelled off. The pigs also sho wed a significant decrease in plasma levels of glucose (6.01 +/- 0.20 to 4. 62 +/- 0.12 mmol/l) within 48 h of fasting, followed by repeated increase u ntil the end of the experimental period. A significant decrease in plasma i nsulin-like growth factor I (84 +/- 13 to 65 +/- 7 ng/ml) was observed afte r 16 h, which continued during the whole period of feed withdrawal However, no significant changes in plasma levels of adrenaline and noradrenaline du ring the period of increased lipolysis were detected. Therefore, the observ ed stimulation of lipolysis in growing swine during fasting is not the resu lt of an increase in plasma concentration of catecholamines.