Abstract
Introduction: Bone loss occurs as a consequence of disuse. Using the hindlimb-unloaded (HU) rat, the purpose of this study was to determine whether skeletal unloading and reloading alters regional bone blood flow (microspheres) and PNA vasodilator responsiveness (in vitro).
Results: Femoral bone and marrow perfusion were reduced after 10 minutes, 7 days and 28 days of HU. Further, when the hindlimb skeleton is reloaded for 10 minutes following 14 days HU, bone and marrow perfusion were lower than that in standing control animals (e.g., femoral proximal metaphysis: Control, 20 ± 3 ml/min/100g; HU, 13 ± 3 ml/min/100g). PNA endothelium-dependent vasodilation was attenuated with 14 days of HU (Control, 84 ± 5% maximal relaxation; HU, 55 ± 7% maximal relaxation).
Discussion: The HU-associated changes bone perfusion and endothelium-dependent vasodilation correspond to unloading-induced changes in bone structure. These results support the hypothesis that alterations in bone blood flow and vascular signaling may modulate bone remodeling.
The abstracts were prepared by Lynne C. Jones, PhD. and Michael A. Mont, MD. Correspondence should be addressed to Lynne C. Jones, PhD., at Suite 201 Good Samaritan Hospital POB, Loch Raven Blvd., Baltimore, MD 21239 USA. Email: ljones3@jhmi.edu
