Bone blood flow in the femora of anesthetized and conscious dogs in a chronic preparation, using the radioactive tracer microsphere method

The radioactive tracer microsphere method is applicable to the study of the hemodynamics of bone. As observed previously by others, areas of predominantly cancellous bone produce higher blood flow measurements than do areas of predominantly cortical bone. Bone containing fatty marrow has lower blood flow rates than does bone containing hematopoietic marrow. Blood flow to the femoral neck was the greatest measured (26.74 ± 1.95 ml/min/100 gm), while the diaphyseal region was the area with the lowest flow (4.67 ± 0.46 ml/min/100 gm). There was no significant difference between consecutive measurements using up to five differently labeled radioactive microspheres. This enabled observations of the effects of an experimental procedure on bone blood flow in the same animal. Additionally, there was no statistically significant difference between regional blood flows measured 40 days apart in the same animal. Bone blood flow measurements were slightly lower in anesthetized than in conscious dogs. The RTM method is the one most suitable for the estimation of bone blood flow under either acute or chronic conditions.