HUMORAL REGULATION OF BLOOD-FLOW IN THE VERTEBRAL END-PLATE

Study Design. Blood flow in the sheep lumbar spine was measured. Objec tives. The effect of vasoactive agents, noradrenaline and acetylcholin e, on blood flow adjacent to the disc-bone interface was determined. S ummary of Background Data. The main route for disc nutrition is throug h 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 lumba r intervertebral discs was measured using the microsphere technique be fore and after infusions of noradrenaline and acetylcholine in two gro ups of five female sheep. Systemic arterial pressure was measured duri ng each infusion. Results. Vertebral bone blood flow was unchanged dur ing 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 exi stence of muscarinic receptors in vessels of the vertebral endplate, w hich suggests that the vasculature may influence disc nutrition.