Humoral regulation of blood flow in the vertebral endplate.

Abstract

Blood flow in the sheep lumbar spine was measured. The effect of vasoactive agents, noradrenaline and acetylcholine, on blood flow adjacent to the disc--bone interface was determined. 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. 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. 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. 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.