WITHDRAWN: Glucose-Dependent Insulinotropic Polypeptide Increases Blood Flow in Adipose Tissue of Humans by Recruiting Capillaries

Context and Objective: Glucose-dependent insulinotropic polypeptide (GIP) in combination with hyperinsulinemia increases blood flow and triglyceride clearance in subcutaneous abdominal adipose tissue in lean humans. The present experiments were performed to determine whether the increase may involve capillary recruitment. Design: Eight lean healthy volunteers were studied before and after 1-hour infusion of GIP or saline during a hyperglycemic-hyperinsulinemic clamp, raising plasma glucose and insulin to postprandial levels. Abdominal subcutaneous adipose tissue blood flow (ATBF) was measured by the [.sup.133]Xe clearance technique, and microvascular volume was determined by contrast-enhanced ultrasound imaging. Results: During infusion of saline and during the clamp, both ATBF (2.7 [+ or -] 0.5 mL/min per 100 g tissue) and microvascular volume remained unchanged throughout the experiments (P not significant). During GIP infusion plus [clamp.sub.,] ATBF increased about fourfold to 11.4 [+ or -] 1.9 mL/min per 100 g tissue, P < 0.001. Likewise, the contrast-enhanced ultrasound signal intensity, a measure of the microvascular volume, increased significantly 1 hour after infusion of GIP and the clamp (P = 0.003) but not in control experiments. Conclusion: The increase in ATBF during GIP infusion involves recruitment of capillaries in healthy lean subjects, which presumably increases the interaction of circulating lipoproteins with lipoprotein lipase, thus probably promoting adipose tissue lipid uptake. (J Clin Endocrinol Metab 104: W2-W9, 2019)