title: Analysis of endothelium-dependent vasodilation by use of the radial artery pulse wave obtained by applanation tonometry.
abstract: OBJECTIVE
  To evaluate applanation tonometry as a method to obtain arterial pulse waves suitable for pulse wave analysis of the height of the diastolic inflection point (IP), and to use this technique to study endothelium-mediated vasodilation by evaluation of the contribution of nitric oxide (NO) to the reduction in the height of the IP induced by beta2-adrenergic stimulation.
  
  
  METHODS
  The radial artery pulse waveform was recorded by applanation tonometry in young healthy subjects before and after interventions both locally in the forearm and systemically by different vasodilators and vasoconstrictors, and vasodilatation was analysed as a change in the height of the IP. The mechanism behind the reduction in the height of the IP induced by terbutaline was investigated by systemic interventions with both N(G)-monomethyl-l-arginine (l-NMMA) and noradrenaline (NA).
  
  
  RESULTS
  Applanation tonometry was a convenient method to obtain radial artery pulse waves of good quality. The reduction in IP was substantially more pronounced when vasodilators were given systemically than when given locally in the forearm, indicating that the effect was obtained through an effect on peripheral pulse wave reflection. Systemically given l-NMMA, but not NA, increased the IP (P<0.05). Systemically given l-NMMA also caused a more pronounced attenuation than NA of the reduction in IP following terbutaline injection (P<0.05).
  
  
  CONCLUSIONS
  Changes in IP following beta2-adrenergic stimulation appears to be a measurement of pulse wave reflection mainly governed by NO. Applanation tonometry and pulse wave analysis is a minimally invasive method suitable to assess endothelium-dependent vasodilation in large-scale studies.
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala, Sweden. lars.lind@medsci.uu.se
authors.forename: Lars
authors.initials: L
authors.lastname: Lind
authors.forename: Knut
authors.initials: K
authors.lastname: Pettersson
authors.forename: Kristina
authors.initials: K
authors.lastname: Johansson
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001916:Brachial Artery; D003971:Diastole; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D006801:Humans; D006830:Hydralazine / Q000008:administration & dosage; D007269:Injections, Intra-Arterial; D009569:Nitric Oxide / Q000502:physiology; D009599:Nitroprusside / Q000008:administration & dosage; D009638:Norepinephrine / Q000008:administration & dosage; D011674:Pulse; D017534:Radial Artery / Q000502:physiology*; D013726:Terbutaline / Q000008:administration & dosage; D014662:Vasoconstrictor Agents / Q000008:administration & dosage; D014664:Vasodilation / Q000502:physiology; D014665:Vasodilator Agents / Q000008:administration & dosage; D019323:omega-N-Methylarginine / Q000008:administration & dosage
chemical_list: D000318:Adrenergic beta-Agonists; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D006830:Hydralazine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013726:Terbutaline; D009638:Norepinephrine