title: Humoral regulation of blood flow in the vertebral endplate.
abstract: METHODS
  Blood flow in the sheep lumbar spine was measured.
  
  
  OBJECTIVE
  The effect of vasoactive agents, noradrenaline and acetylcholine, on blood flow adjacent to the disc--bone interface was determined.
  
  
  BACKGROUND
  The main route for disc nutrition is through the vertebral endplate. Although the vascular anatomy in this region has been well described, its response to neurohumoral influences has not been quantified.
  
  
  METHODS
  Blood flow in bone adjacent to the lumbar intervertebral discs was measured using the microsphere technique before and after infusions of noradrenaline and acetylcholine in two groups of five female sheep. Systemic arterial pressure was measured during each infusion.
  
  
  RESULTS
  Vertebral bone blood flow was unchanged during noradrenaline infusion, but increased by 60% during acetylcholine infusion. This was associated with a significant decrease in systemic arterial pressure.
  
  
  CONCLUSIONS
  These data are consistent with the existence of muscarinic receptors in vessels of the vertebral endplate, which suggests that the vasculature may influence disc nutrition.
authors.affiliation: Department of Orthopaedic Surgery, St. George Hospital, Sydney, Australia.
authors.forename: A L
authors.initials: AL
authors.lastname: Wallace
authors.forename: B C
authors.initials: BC
authors.lastname: Wyatt
authors.forename: I D
authors.initials: ID
authors.lastname: McCarthy
authors.forename: S P
authors.initials: SP
authors.lastname: Hughes
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D008159:Lumbar Vertebrae / Q000098:blood supply*; D009638:Norepinephrine / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D012965:Sodium Chloride; D000109:Acetylcholine; D009638:Norepinephrine