Blood flow in canine tibial diaphysis estimated by iodoantipyrine- 125 I washout.

Tibial bone blood flow was estimated in dogs by an indicator washout method using (125)I-labeled 4-iodoantipyrine (I-Ap). The tibial cortical bone/blood partition coefficient, λ, of I-Ap was (mean ± sd) 0.150 ± 0.027 for 17 dogs. Tibial cortical bone blood flow (mean ± sd) was 0.0152 ± 0.003 ml/ml bone per min by the residue function technique of Zierler applied to 32 washout curves. Exponential analysis by the successive subtraction method gave the same mean value and, if the flow were considered to traverse two regions in parallel, suggested that 22% (sd, ±7.4) of the indicator traversed a high-flow region (mean flow, 0.265 ml/ml bone per min; sd, ±0.194) and the remainder had a mean flow of 0.0118 ml/ml bone per min (sd, ± 0.003).