title: beta2-adrenergic receptor polymorphisms at amino acid 16 differentially influence agonist-stimulated blood pressure and peripheral blood flow in normal individuals.
abstract: BACKGROUND
  The Gly16 beta(2)-adrenergic receptor (beta(2)AR) polymorphism is a common variant of the beta(2)AR that displays depressed function caused by enhanced receptor downregulation in vitro compared with the Arg16 receptor.
  
  
  RESULTS
  We studied 20 healthy, normotensive, nonsmoking white individuals who were homozygous for either the Arg16 (n = 10) or the Gly16 (n = 10) genotype. Plethysmographic lower-limb blood flow, blood pressure, and 2-dimensional echocardiograms were recorded at baseline and after 15-minute incremental infusions of terbutaline (100 to 300 ng/kg per minute). Baseline heart rates, blood pressures, and flows were similar in both groups, but at the maximum dose of terbutaline, limb blood flow was less (P <.05), calculated vascular resistance was greater (P <.05), and systolic and diastolic blood pressures were greater in patients with Gly16 than in those with Arg16 (both P <.05). In contrast, terbutaline-stimulated heart rates were not different. In a separate group of 20 homozygous individuals (12 Arg16, 8 Gly16), there were no differences in 2-dimensional echocardiographically determined ventricular function.
  
  
  CONCLUSIONS
  We conclude that the Gly16 beta(2)AR polymorphism imparts attenuated vasodilatory responses to catecholamines in normal human beings and is an important genetic component in the regulation of peripheral blood flow and systemic arterial pressure.
authors.affiliation: Division of Cardiology and the Departments of Medicine and Pharmacology, University of Cincinnati, Ohio, USA. bdh6@po.cwru.edu
authors.forename: B D
authors.initials: BD
authors.lastname: Hoit
authors.forename: D P
authors.initials: DP
authors.lastname: Suresh
authors.forename: L
authors.initials: L
authors.lastname: Craft
authors.forename: R A
authors.initials: RA
authors.lastname: Walsh
authors.forename: S B
authors.initials: SB
authors.lastname: Liggett
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000328:Adult; D019943:Amino Acid Substitution / Q000235:genetics*; D001794:Blood Pressure / Q000187:drug effects / Q000235:genetics; D004452:Echocardiography; D005260:Female; D005838:Genotype; D006339:Heart Rate / Q000187:drug effects / Q000235:genetics; D006439:Hemodynamics / Q000187:drug effects / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D015588:Observer Variation; D010991:Plethysmography; D011110:Polymorphism, Genetic / Q000502:physiology*; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics*; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects / Q000235:genetics; D013318:Stroke Volume / Q000187:drug effects / Q000235:genetics; D013726:Terbutaline / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D018343:Receptors, Adrenergic, beta-2; D013726:Terbutaline