Lemons D E, Chien S, Crawshaw L I, Weinbaum S, Jiji L M
Am J Physiol. 1987 Jul;253(1 Pt 2):R128-35. doi: 10.1152/ajpregu.1987.253.1.R128.
This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- and macrovascular heat transfer by experimentally identifying those vessels most important in the process. Tissue temperature fields around thermally nonequilibrated vessels were determined using a small temperature sensor that was guided through the rabbit thigh to generate a detailed temperature map. The measurements revealed that the lower limit of vessel size for thermal nonequilibration was 100 microns for arteries and 400 microns for veins. Local temperature fields were found around four of the five (80%) arteries that were greater than 300 microns in diameter but in only 3 of the 12 (25%) veins greater than 400 microns. These experimental results are in good agreement with previously published theoretical studies (5) in which it was concluded that thermal equilibration in the branching countercurrent vascular network of the rabbit limb occurs in vessels an order of magnitude larger than the capillaries. In those studies the smallest vessels capable of carrying heat were predicted to be 50 microns ID with the major blood tissue heat exchange occurring in vessels greater than 100 micron ID. These findings contrast with the view that most heat transfer occurs in the capillaries and suggest that vascular heat transfer analysis must take into account the vascular architecture of the 50- to 1,000-micron vessels where most heat transfer occurs.
本研究旨在通过实验确定该过程中最重要的血管，从而更好地理解微血管和大血管的传热基本机制。使用一个小型温度传感器来测定热非平衡血管周围的组织温度场，该传感器通过兔大腿引导以生成详细的温度图。测量结果显示，热非平衡的血管尺寸下限对于动脉为100微米，对于静脉为400微米。在直径大于300微米的五条动脉中的四条（80%）周围发现了局部温度场，但在直径大于400微米的12条静脉中仅在三条（25%）周围发现了局部温度场。这些实验结果与先前发表的理论研究（5）高度一致，在该研究中得出结论，兔肢体分支逆流血管网络中的热平衡发生在比毛细血管大一个数量级的血管中。在那些研究中，预测能够传热的最小血管内径为50微米，主要的血液与组织热交换发生在内径大于100微米的血管中。这些发现与大多数传热发生在毛细血管中的观点形成对比，并表明血管传热分析必须考虑到大多数传热发生的50至1000微米血管的血管结构。
