Use of labeled microspberes for simultaneous determination of total and regional blood flows in canine femur

A vascularized allograft canine tibia was used to evaluate the preservation of the osseous microcirculation. Six pairs of adult tibiae were harvested, and a vascular washout was performed with mannitol solution. The bones then were perfused continuously (0.03 ml/min at 5 degrees C) for 20 hours with University of Wisconsin solution. Following storage, each pair of bones was transplanted, by microvascular anastomosis, to a recipient dog, and bone blood flow was estimated using the radiolabeled microsphere method. Adrenoreceptor control mechanisms were evaluated in one specimen, and endothelial function was evaluated in the contralateral specimen. Alpha 1-adrenoreceptor blockade produced a significant increase (89 +/- 80%) in bone blood flow (p < 0.05). A further increase (99 +/- 56%) was observed with the addition of alpha 2-blockade (p < 0.01). Acetylcholine produced a decrease (65 +/- 65%) in blood flow (p < 0.01). This effect was inhibited by L-NG-monomethyl-arginine, which resulted in an increase (53 +/- 47%) in bone blood flow (p < 0.05). The no-reflow phenomenon was observed in two vascularized allografts. These results demonstrate that smooth muscle adrenoreceptors were preserved successfully for 24 hours. In contrast, endothelial function was abnormal. There was no evidence that the endothelium was producing endothelium-derived relaxing factor, and the results suggest that an endothelium-derived constricting factor dependent on L-arginine was produced during reperfusion. It is concluded that University of Wisconsin solution does not preserve normal endothelial function in the microcirculation of bone.

Section: Measurement Of Bone Blood Flowmentioning

confidence: 99%

Reperfusion injury in vascularized bone allografts

McGrory

Bronk

Wood

1995

Quantification of regional blood flow to canine flexor tendons

Weidman

Simonet

Wood

et al. 1984

Although the blood supply and the microcirculation of flexor tendons have been studied and defined extensively using qualitative methods, the quantitative assessment of blood flow has been lacking because of the limitations of the available experimental techniques. We studied the regional blood supply to the flexor tendons of dogs by the technique of radionuclide-labeled microspheres. Seven adult mongrel dogs were used. Microsphere injection and tissue-counting techniques previously used for other tissues were applied. Samples of proximal, isthmus, and distal portions of the profundus and superficialis flexor tendons were harvested from each digital unit of available limbs from each dog. Mean (+/- SE) flows (ml/100 g dry tissue/min) were proximal profundus 1.78 +/- 0.60 and superficialis 7.10 +/- 1.50. The differences were significant (p less than 0.01). The study suggests that regional variation in blood flow to canine digital flexor tendons exists, so that a single value for blood flow to these tendons is not relevant. Furthermore, the study supports the concept of dual (vascular and synovial) nutrition to the digital flexor tendons in dogs. These observations may have implications regarding tendon repair techniques.

Canine bone blood flow estimated with microspheres

Bronk

Kelly

1989

Blood flow rate in the periosteal and endosteal cortices of the diaphysis of long bones was determined in eight anesthetized adult dogs using the radioactively labeled microsphere method. The flow rate in endosteal and periosteal cortices is not significantly different unless the endosteal cortex contains cancellous bone from the medullary cavity. The highest flow rate is in the ulna, with 6.50 ml/min/100 g for the endosteal cortex and 5.15 ml/min/100 g for the periosteal cortex. The lowest flow rate is in the femur, with 2.89 ml/min/100 g for the endosteal cortex and 2.29 ml/min/100 g for the periosteal cortex. The results of this study indicate that variation of blood flow does exist between bones of dogs. However, the flow rates of individual bone on the left and right sides in the same dog are not significantly different. This indicates that the data are reproducible and reliable, and differences are not an inaccuracy of the radioactively labeled microsphere method. The results also demonstrate that there are no significant differences in bone blood flow as measured with small numbers (fewer than 400 microspheres per sample) and large numbers (more than 400 microspheres per sample) of microspheres. The adequate number of microspheres in each bone sample is 150-250. Therefore, a dose of 0.5 x 10(6) spheres/kg body weight can be sufficient.