Experimental measurements of the temperature variation along artery-vein pairs from 200 to 1000 μm diameter in rat hind limb

摘要

Theoretical studies have indicated that a significant fraction of all blood-tissue heat transfer occurs in blood vessels between 200 and 1000 μm in diameter. In this study, in vivo experiments were performed on the rat hind limb to examine for the first time the thermal equilibration along thermally significant artery-vein pairs ranging from 200 μm to 1000 μm diameter. Several fine thermocouples were attached to the femoral vessels and their subsequent branches to measure the axial temperature variation and countercurrent heat exchange under different physiological conditions. Changes in the blood flow rate of the vessels were induced by vasoactive drugs. It is therefore, possible to experimentally examine the relationship between the local blood perfusion and the thermal equilibration length. These measurements of the local vascular temperature field were then used to evaluate the fundamental assumptions introduced by different continuum models.