title: Increased blood pressure induces a diameter response of retinal arterioles that increases with decreasing arteriolar diameter.
abstract: OBJECTIVE
  To study the diameter response of retinal arterioles as a function of the arteriolar diameter.
  
  
  METHODS
  Ten healthy young volunteers aged 22 to 33 years were subjected to diameter measurement of four successive segments of a retinal arteriole with a retinal vessel analyzer (RVA). At each of the segments, the diameter response during an increase in the systemic blood pressure (mean arterial pressure [MAP]) induced by isometric exercise was compared to the diameter of the arterioles during rest.
  
  
  RESULTS
  The isometric exercise induced a significant contraction of the studied vessel segments averaging 2.5% +/- 0.4% (P < 0.0001, n = 40). There was a significant negative correlation between the baseline diameter of the studied vessel segments and the diameter response induced by isometric exercise (P = 0.02).
  
  
  CONCLUSIONS
  The blood pressure-induced diameter response of retinal arterioles increased with decreasing diameter of the vessels. The results indicate that the distal retinal arterioles play a major role in the regulation of retinal blood flow.
authors.affiliation: Department of Ophthalmology, Arhus University Hospital, Arhus, Denmark. pj@dadlnet.dk
authors.forename: Peter
authors.initials: P
authors.lastname: Jeppesen
authors.forename: Javad
authors.initials: J
authors.lastname: Sanye-Hajari
authors.forename: Toke
authors.initials: T
authors.lastname: Bek
mesh_terms: D000328:Adult; D001160:Arterioles / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D008833:Microcirculation; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology