title: Heterogeneous vascular response to vasopressin: radial artery versus forearm blood flow.
abstract: BACKGROUND
  Arginine vasopressin (AVP) administered intra-arterially to normal volunteers exerts a biphasic effect on forearm blood flow when the effect is extrapolated from plethysmographic measurements.
  
  
  OBJECTIVE
  To assess whether the high-dose AVP-induced increase in forearm blood flow could be confirmed when calculating blood flow from continuous radial artery diameter and flow velocity recordings obtained by using a high-resolution echotracking device combined with a Doppler system.
  
  
  METHODS
  Increasing doses (0.04-0.8 ng/kg per min) of AVP were infused into a brachial artery of seven normal male volunteers (aged 21-33 years). Forearm blood flow derived from venous occlusion plethysmography was assessed simultaneously with proximal radial artery blood flow calculated from luminal area and flow velocity measurements.
  
  
  RESULTS
  Confirming previous reports, plethysmography showed an increase in global forearm blood flow by > 100% with AVP concentrations > or = 0.2 ng/kg per min. In contrast, direct measurements of lumen diameter and blood flow velocity in the radial artery revealed a marked dose-dependent vasoconstriction with a > 30% decline in blood flow at the highest AVP concentration.
  
  
  CONCLUSIONS
  The discrepancy between the two measurements suggests that AVP has a dual effect on forearm haemodynamics. At high AVP concentration, the muscle blood flow increase predominates over the vasoconstriction in the skin circulation. Furthermore, this study strongly suggests a heterogeneity of the vascular response to vasomediators by showing that opposing responses exist not only between resistive and conduit vessels but also between conduit arteries of a common vascular bed.
authors.affiliation: Division of Hypertension, CHUV, Lausanne, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Hayoz
authors.forename: R
authors.initials: R
authors.lastname: Weber
authors.forename: A
authors.initials: A
authors.lastname: Pechère
authors.forename: M
authors.initials: M
authors.lastname: Burnier
authors.forename: H R
authors.initials: HR
authors.lastname: Brunner
mesh_terms: D000328:Adult; D001127:Arginine Vasopressin / Q000008:administration & dosage*; D001783:Blood Flow Velocity / Q000187:drug effects; D005542:Forearm / Q000098:blood supply; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007261:Infusions, Intra-Arterial; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply; D010991:Plethysmography; D017534:Radial Artery / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000098:blood supply; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D001127:Arginine Vasopressin