COMPARATIVE EFFECTS OF RECOMBINANT HUMAN INSULIN-LIKE GROWTH-FACTOR-IAND INSULIN ON WHOLE-BODY AND FOREARM PALMITATE METABOLISM IN MAN

1. The effects of intravenous infusions of recombinant human insulin-l ike growth factor I and insulin on palmitate kinetics, lipolysis and o n serum triacylglycerol were compared. Overnight-fasted normal subject s received high doses of insulin-like growth factor I (30 mu g h(-1) k g(-1)) and insulin (0.23 nmol h(-1) kg(-1); group 1), low doses of ins ulin-like growth factor I (5 mu g h(-1) kg(-1)) and insulin (0.04 nmol h(-1) kg(-1) group 2) or saline (control group), The doses of insulin -like growth factor I and insulin were equipotent with regard to incre ases in glucose uptake during 8 h euglycaemic clamping 2. Whole-body p almitate flux (measured by continuous infusions of [2,2D(2)]palmitate) was lowered dose-dependently by 68% +/- 6% during insulin-like growth factor I and by 82% +/- 2% during insulin after 8 h of infusions of h igh doses (insulin-like growth factor I versus insulin; not significan t). Plasma palmitate, glycerol and triacylglycerol concentrations had decreased to a similar extent at the end of the infusions of both pept ides at either dose. 3. The present results demonstrate that insulin-l ike growth factor I and insulin infused at doses which result in ident ical increases in glucose uptake during euglycaemic clamping are equip otent inhibitors of lipolysis.