title: Evidence of an autoregulatory mechanism of regional bone blood flow at hypotension.
abstract: BACKGROUND
  Blood flow in various organs is determined by an autoregulatory mechanism that guarantees constant organ perfusion over a wide range of arterial blood pressure changes. This physiological principle has been proven for the kidney, brain and intestinal tract, but so far not for bone. This study was carried out to determine whether there is an autoregulatory mechanism of bone or not.
  
  
  METHODS
  The fluorescent microsphere reference sample method was used to determine blood flow within the bone and kidneys. Eight anesthetized female New Zealand rabbits received left ventricular injections of fluorescent microspheres over a wide range of arterial pressure levels prior to removal of kidney, femur and tibia. Blood flow values were calculated by measurement of fluorescence intensity in kidney and bone and correlated to fluorescence intensity in the peripheral blood (reference sample).
  
  
  RESULTS
  Despite a reduction of mean arterial pressure from 100 to 80 mmHg bone blood flow remained constant. Further reduction of mean arterial pressure results in a linear decrease in bone blood flow.
  
  
  CONCLUSIONS
  The correlation between arterial pressure and organ perfusion in the bone is similar to blood flow within the kidney, indicating the presence of an autoregulated blood flow mechanism within the bone tissue.
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Straße 22, Munich, Germany. stephan-vogt@web.de
authors.forename: Stephan
authors.initials: S
authors.lastname: Vogt
authors.forename: Arne J
authors.initials: AJ
authors.lastname: Venjakob
authors.forename: Klaus
authors.initials: K
authors.lastname: Stöckl
authors.forename: Thomas
authors.initials: T
authors.lastname: Tischer
authors.forename: Philipp J
authors.initials: PJ
authors.lastname: Jost
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Imhoff
authors.forename: Eckart
authors.initials: E
authors.lastname: Thein
authors.forename: Hermann
authors.initials: H
authors.lastname: Anetzberger
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000098:blood supply*; D005260:Female; D007022:Hypotension / Q000503:physiopathology*; D007668:Kidney / Q000098:blood supply; D011817:Rabbits; D012039:Regional Blood Flow / Q000502:physiology*