title: Effects of norepinephrine infusion on in vivo insulin sensitivity and responsiveness.
abstract: The effect of a continuous infusion of norepinephrine (NE) on glucose disposal in vivo was examined in conscious restrained rats using the euglycemic-hyperinsulinemic clamp technique. NE, 1,000 micrograms.kg-1.day-1 (130 nmol.kg-1.h-1) or vehicle (CO) was infused for 10 days in adult male Sprague-Dawley rats using subcutaneously implanted osmotic minipumps. Body weight and food intake were similar in both groups of animals throughout the study. Fasting basal plasma glucose and insulin concentrations were similar in both groups. However, basal hepatic glucose production (HGP) was increased by NE treatment (9.03 +/- 0.63 vs. 13.20 +/- 1.15 mg.kg-1.min-1, P less than 0.05, CO vs. NE, respectively). Insulin infusions of 2, 6, and 200 mU.kg-1.min-1 suppressed HGP to the same degree in both groups. During 2, 6, and 200 mU.kg-1.h-1 insulin infusions the glucose disposal rate was 65, 60, and 13% greater in NE-treated animals than in controls. Acute beta-adrenergic blockade with propranolol infused at 405 nmol.kg-1.h-1 during the glucose clamps did not normalize glucose disposal. These results demonstrate that chronic NE infusion is associated with increased basal glucose turnover and increased insulin sensitivity of peripheral tissues.
authors.affiliation: Department of Medicine, University of Vermont, College of Medicine, Burlington 05405.
authors.forename: J R
authors.initials: JR
authors.lastname: Lupien
authors.forename: M F
authors.initials: MF
authors.lastname: Hirshman
authors.forename: E S
authors.initials: ES
authors.lastname: Horton
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D006003:Glycogen / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007332:Insulin Infusion Systems; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism; D009638:Norepinephrine / Q000097:blood / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008112:Liver Glycogen; D006003:Glycogen; D011433:Propranolol; D006006:Glycogen Synthase; D005947:Glucose; D009638:Norepinephrine