AJP - Heart and Circulatory Physiology, Vol 256, Issue 5 1261-H1265, Copyright © 1989 by American Physiological Society
Multiple tracer studies of bone uptake of 99mTc-MDP and 85Sr
I. D. McCarthy and S. P. Hughes
Department of Orthopaedic Surgery, University of Edinburgh, Scotland.
Multiple tracer outflow dilution studies were performed on the normal
canine tibia. In all cases 125I-labeled albumin was used as a vascular
tracer. In one series of experiments 99mTc-labeled methylene diphosphonate
and [14C]sucrose were used as test tracers, and in a second series 85Sr and
22Na were used. A bolus of three tracers was injected into the tibial
nutrient artery, and fractional concentrations appearing in the ipsilateral
femoral vein were measured for a period of 5 min. A distributed model,
containing parameters for capillary and bone permeability and apparent
volumes of distribution of interstitial fluid, was fitted to these data. It
was found that there was no discrimination between movement of 85Sr or 22Na
from interstitial fluid space into bone. Transcapillary exchange does not
appear to be a significant barrier to exchange between blood and bone
surfaces.
