The effects of glucose-dependent insulinotropic polypeptide on net splanchnic blood flow in lean humans

CONTEXT: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone with potent vasoactive and metabolic effects in adipose tissue, but its effects on splanchnic blood flow (SBF) in humans remain unclear. Investigating potential regional differences is important for understanding the vascular actions of GIP in humans. OBJECTIVE: The aim of this study was to examine the effects of GIP on SBF, both independently and in combination with hyperglycemia and hyperinsulinemia. METHODS: In a randomized, controlled crossover study, 8 healthy, lean male participants underwent 4 separate experimental conditions. The interventions included intravenous infusions of either GIP at a rate of 1.5 pmol-1 kg-1 minute-1 or saline, administered alone or in combination with a hyperglycemic and hyperinsulinemic clamp, respectively. Splanchnic blood flow was measured by Fick's Principle after catheterization of a hepatic vein, using indocyanine green as indicator. RESULTS: Splanchnic blood flow remained comparable across all experimental conditions, including GIP and saline infusions, both with and without the hyperglycemic and hyperinsulinemic clamp (P = .42). CONCLUSION: Under the applied conditions, GIP does not appear to play a substantial role in the acute regulation of net SBF, either alone or in combination with induced hyperglycemia and hyperinsulinemia.