The aim of this study was to investigate the effect of glucose-dependent insulinotropic polypeptide (GIP) per se and in combination with hyperglycemia and hyperinsulinemia on splanchnic blood flow and further to investigate the role of GIP in splanchnic lipid metabolism in humans. Eight healthy lean males were examined in a randomized order on four different occasions. Splanchnic blood flow and lipid metabolism were measured by Fick’s Principle using indocyanine green as indicator during GIP (1.5 pmol/kg/min) or saline infused intravenously alone or in combination with a hyperglycemia and hyperinsulinemia (Hygluc-Hyinsu) clamp. During all four experiments, splanchnic blood flow increased similarly. Splanchnic triglyceride output decreased similarly during the Hygluc-Hyinsu clamp with and without GIP (8.6 ± 1.8 and 10.3 ± 2.6 µmol/min, respectively, P=NS). Likewise, during the clamp alone and with GIP, free fatty acids uptake decreased similarly (3.5 ± 3.8 and 6.7 ± 4.6 µmol/min, respectively, P=NS). GIP does not seem to play a key role in the acute regulation of splanchnic blood flow or lipid metabolism under these particular conditions in vivo.
A. Asmar: None. J.J. Holst: Advisory Panel; Self; Novo Nordisk A/S. M. Asmar: None.