title: A combined test of acetylcholine-mediated vasodilation of both the forearm resistance vessels and the radial artery.
abstract: OBJECTIVE
  To evaluate a new combined test of endothelium-dependent vasodilation (EDV) in the forearm resistance vessel and the radial artery.
  
  
  METHODS
  Acetylcholine (ACh) and sodium nitroprusside (SNP) infusion in the brachial artery were used to simultaneous evaluate EDV and endothelium-independent vasodilation (EIDV) in forearm resistance vessels (plethysmography) and in the radial artery (ultrasound) in 76 healthy subjects. Brachial artery ultrasound was used to assess flow-mediated vasodilation (FMD).
  
  
  RESULTS
  Acetylcholine induced a 4·5% (median value, P = 0·0010) increase in the radial artery diameter, while SNP induced a 31·2% increase in diameter (P<0·0001). While no increase in radial artery blood flow was induced by ACh (P = 0·69), an increase by 181% in radial blood flow was induced by SNP (P<0·0001). When relating the radial artery diameter data to FMD, the change in radial artery diameter induced by ACh was significantly correlated with FMD (r = 0·35, P = 0·013). No such relationship was seen for the diameter change induced by SNP (r = -0·03, P = 0·81). When relating the radial artery blood flow data to EDV and EIDV, the change in radial artery blood flow induced by ACh was significantly correlated with EDV in an inverse fashion (r = -0·42, P = 0·0032). No such relationship was seen for the blood flow change induced by SNP when related to EIDV (r = -0·07, P = 0·63).
  
  
  CONCLUSIONS
  Simultaneous measurements of blood flow in forearm vessels by plethysmography and in the radial artery by ultrasound during ACh infusion is a new way to assess EDV in both resistance and conduit arteries during one investigation.
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala University, Uppsala, Sweden. lars.lind@medsci.uu.se
authors.forename: Lars
authors.initials: L
authors.lastname: Lind
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage; D000367:Age Factors; D000368:Aged; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D003935:Diagnostic Techniques, Cardiovascular; D004730:Endothelium, Vascular / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D007261:Infusions, Intra-Arterial; D008297:Male; D008875:Middle Aged; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D010991:Plethysmography; D017534:Radial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D014655:Vascular Resistance; D014664:Vasodilation; D014665:Vasodilator Agents / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D020030:Nitric Oxide Donors; D014665:Vasodilator Agents; D009599:Nitroprusside; D000109:Acetylcholine