title: Effect of interference current on forearm vascular resistance in asymptomatic humans.
abstract: OBJECTIVE
  Several case reports suggest that transcutaneous application of interference current (IC) produces physical blockade of sympathetic vasoconstrictor fibers in peripheral nerves. To test this theory, we studied the effects of IC on forearm vascular resistance in asymptomatic humans.
  
  
  METHODS
  One man and four women, aged 21 to 44 years (mean = 33, SD = 12), served as subjects.
  
  
  METHODS
  We measured forearm blood flow during IC applications over the left stellate ganglion. Forearm vascular resistance was calculated by dividing mean arterial pressure by forearm blood flow.
  
  
  RESULTS
  Interference current did not alter flow (mean = 5.6 [SD = 1.0] versus 6.2 [SD = 1.1] mL/100 mL/min) or resistance (mean = 15.4 [SD = 3.1] versus 13.8 [SD = 2.4] units). When sympathetic outflow was augmented using lower-body suction, IC again failed to alter flow or resistance.
  
  
  CONCLUSIONS
  Interference current applied over the stellate ganglion does not alter forearm hemodynamics in asymptomatic individuals. These findings challenge the concept that IC can block sympathetic vasoconstrictor impulses in peripheral nerves.
authors.affiliation: Physical Therapy Center of Rhinelander, WI 54501.
authors.forename: H J
authors.initials: HJ
authors.lastname: Indergand
authors.forename: B J
authors.initials: BJ
authors.lastname: Morgan
mesh_terms: D000320:Adrenergic Fibers / Q000502:physiology; D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D005260:Female; D005542:Forearm / Q000098:blood supply* / Q000294:innervation; D006801:Humans; D008297:Male; D010991:Plethysmography; D012881:Skin Temperature; D004561:Transcutaneous Electric Nerve Stimulation; D014655:Vascular Resistance