title: The effect of vasopressin on choroidal blood flow, intraocular pressure, and orbital venous pressure in rabbits.
abstract: OBJECTIVE
  To investigate the effects of arginine-vasopressin (AVP) on intraocular pressure (IOP), orbital venous pressure (OVP), and choroidal blood flow (ChorBF) regulation in anesthetized rabbits.
  
  
  METHODS
  Mean arterial pressure (MAP), IOP, and OVP were measured by direct cannulation of the central ear artery, the vitreous, and the orbital venous sinus, respectively. Laser Doppler flowmetry was used to record ChorBF. To change the perfusion pressure (PP), MAP was manipulated mechanically with occluders around the aorta and vena cava. In the first group of animals (n = 11) the dose-response relationship was measured. In the second group of animals (n = 8) pressure-flow relationships were determined at baseline and in response to intravenous application of a low (0.08 ng/kg/min) and a high (1.33 ng/kg/min) infusion rate of AVP.
  
  
  RESULTS
  AVP caused a dose-dependent increase of MAP and choroidal vascular resistance (ChorR), whereas IOP, OVP, ChorBF, and heart rate (HR) were decreased. In contrast to the high infusion rate, the low infusion rate of AVP had no effect on baseline ChorBF. However, the pressure-flow relationship was shifted downward significantly by both infusion rates at PP below baseline.
  
  
  CONCLUSIONS
  AVP reduces IOP and OVP significantly and is a potent vasoconstrictor in the choroidal vascular bed. In the choroid, the effect of AVP is not only dose-dependent, but also PP-dependent, which is indicated by the reduced perfusion relative to control with low-dosed AVP at low PP.
authors.affiliation: Department of Ophthalmology and Optometry, SALK/Paracelsus Medical University, Salzburg, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bogner
authors.forename: Birgit
authors.initials: B
authors.lastname: Tockner
authors.forename: Christian
authors.initials: C
authors.lastname: Runge
authors.forename: Clemens
authors.initials: C
authors.lastname: Strohmaier
authors.forename: Andrea
authors.initials: A
authors.lastname: Trost
authors.forename: Manuela
authors.initials: M
authors.lastname: Branka
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Radner
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Kiel
authors.forename: Falk
authors.initials: F
authors.lastname: Schroedl
authors.forename: Herbert A
authors.initials: HA
authors.lastname: Reitsamer
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002829:Choroid / Q000098:blood supply*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous; D007429:Intraocular Pressure / Q000187:drug effects*; D017078:Laser-Doppler Flowmetry; D008297:Male; D009915:Orbit / Q000098:blood supply; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014690:Venous Pressure / Q000187:drug effects
chemical_list: D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin