title: Glucagon-like peptide 1 recruits muscle microvasculature and improves insulin's metabolic action in the presence of insulin resistance.
abstract: Glucagon-like peptide 1 (GLP-1) acutely recruits muscle microvasculature, increases muscle delivery of insulin, and enhances muscle use of glucose, independent of its effect on insulin secretion. To examine whether GLP-1 modulates muscle microvascular and metabolic insulin responses in the setting of insulin resistance, we assessed muscle microvascular blood volume (MBV), flow velocity, and blood flow in control insulin-sensitive rats and rats made insulin-resistant acutely (systemic lipid infusion) or chronically (high-fat diet [HFD]) before and after a euglycemic-hyperinsulinemic clamp (3 mU/kg/min) with or without superimposed systemic GLP-1 infusion. Insulin significantly recruited muscle microvasculature and addition of GLP-1 further expanded muscle MBV and increased insulin-mediated glucose disposal. GLP-1 infusion potently recruited muscle microvasculature in the presence of either acute or chronic insulin resistance by increasing muscle MBV. This was associated with an increased muscle delivery of insulin and muscle interstitial oxygen saturation. Muscle insulin sensitivity was completely restored in the presence of systemic lipid infusion and significantly improved in rats fed an HFD. We conclude that GLP-1 infusion potently expands muscle microvascular surface area and improves insulin's metabolic action in the insulin-resistant states. This may contribute to improved glycemic control seen in diabetic patients receiving incretin-based therapy.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Chai
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VADepartment of Pediatrics, Central South University 2nd Xiangya Hospital, Hunan, China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA.
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Barrett
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA zl3e@virginia.edu.
authors.forename: Zhenqi
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D059305:Diet, High-Fat; D052216:Glucagon-Like Peptide 1 / Q000008:administration & dosage / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008055:Lipids / Q000009:adverse effects; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007328:Insulin; D008055:Lipids; D052216:Glucagon-Like Peptide 1; D005947:Glucose