title: Obesity blunts microvascular recruitment in human forearm muscle after a mixed meal.
abstract: OBJECTIVE
  Ingestion of a mixed meal recruits flow to muscle capillaries and increases total forearm blood flow in healthy young lean people. We examined whether these vascular responses are blunted by obesity.
  
  
  METHODS
  We fed eight middle-aged lean and eight obese overnight-fasted volunteers a liquid mixed meal (480 kcal). Plasma glucose and insulin were measured every 30 min, and brachial artery flow and muscle microvascular recruitment (contrast ultrasound) were assessed every 60 min over 2 h after the meal.
  
  
  RESULTS
  By 30 min, plasma glucose rose in both the lean (5.1 +/- 0.1 vs. 6.7 +/- 0.4 mmol/l, P < 0.05) and the obese groups (5.4 +/- 0.2 vs. 6.7 +/- 0.4 mmol/l, P < 0.05). Plasma insulin rose (28 +/- 4 vs. 241 +/- 30 pmol/l, P < 0.05) by 30 min in the lean group and remained elevated for 2 h. The obese group had higher fasting plasma insulin levels (65 +/- 8 pmol/l, P < 0.001) and a greater postmeal area under the insulin-time curve (P < 0.05). Brachial artery flow was increased at 120 min after the meal in the lean group (38 +/- 6 vs. 83 +/- 16 ml/min, P < 0.05) but not in the obese group. Muscle microvascular blood volume rose by 120 min in the lean group (14.4 +/- 2.2 vs. 24.4 +/- 4.2 units, P < 0.05) but not in the obese group.
  
  
  CONCLUSIONS
  A mixed meal recruits muscle microvasculature in lean subjects, and this effect is blunted by obesity. This impaired vascular recruitment lessens the endothelial surface available and may thereby impair postprandial glucose disposal.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia, USA. michelle.keske@menzies.utas.edu.au
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Keske
authors.forename: Lucy H
authors.initials: LH
authors.lastname: Clerk
authors.forename: Wendie J
authors.initials: WJ
authors.lastname: Price
authors.forename: Linda A
authors.initials: LA
authors.lastname: Jahn
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Barrett
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D055806:Microvessels / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D019518:Postprandial Period
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D007328:Insulin