The distribution of blood flow to the whole skeleton in dogs, rabbits and rats measured with microspheres.

The distribution of blood flow to the skeleton was studied by injecting radioactive microspheres into the hearts of anaesthetised adult animals and measuring activity in individual bones and groups of bones. The mean proportion of the cardiac output delivered to the whole skeleton was 7.5% in dogs, 4.2% in rabbits and 4.5% in rats. The results throw doubt on the value for rats of 27% published by Brookes. There was a wide range of flow per unit mass of bone in different parts of the skeleton, demonstrating the inaccuracy of predicting total skeletal flow from measurements on a single bone. The relative distribution to different parts of the skeleton was similar in the three species, but there were quantitative differences.