Menninger R P, Baker C H
Am J Physiol. 1976 Jun;230(6):1561-8. doi: 10.1152/ajplegacy.1976.230.6.1561.
An attempt is made to determine whether hypothalamically induced forelimb vascular dilation in the dog affects primarily exchange beds or shunt circuits. Slug injections of [131I] albumin and 86RbCl were used to measure the active vascular volume of the forelimbs and permeability surface area product (PS), respectively. Changes in total vascular volume (TVV), filtration, and capillary filtration coefficient (CFD) were measured by plethysmography. During stimulation, forelimb blood flow increased 25% and TVV increased an average 1.5 ml. There was no plethysmographic evidence of outward capillary filtration. Active vascular volume decreased 11%. PS decreased 11%, and CFC decreased 20%. These results point to a redistribution of blood flow from exchange circuits to faster flow channels. During constant-inflow perfusion, there was evidence from CFC and PS measurements that the capillary surface area was increased while active vascular volume decreased. The results observed with hypothalamic stimulation are different from those obtained with pharmacologic dilators and denervation. It is suggested that the former method has a more selective effect in lowering resistance in the faster shuntlike vessels.
本研究旨在确定犬下丘脑诱发的前肢血管扩张主要影响的是交换床还是分流回路。分别通过注射[131I]白蛋白和86RbCl来测量前肢的有效血管容积和通透表面积乘积（PS）。通过体积描记法测量总血管容积（TVV）、滤过率和毛细血管滤过系数（CFD）的变化。刺激过程中，前肢血流量增加25%，TVV平均增加1.5 ml。体积描记法未显示有毛细血管外向滤过的证据。有效血管容积减少11%。PS减少11%，CFC减少20%。这些结果表明血流从交换回路重新分布到流速更快的通道。在恒流灌注期间，根据CFC和PS测量结果，有证据表明毛细血管表面积增加而有效血管容积减少。下丘脑刺激所观察到的结果与使用药物扩张剂和去神经支配所获得的结果不同。提示前一种方法在降低类似分流的流速更快的血管阻力方面具有更具选择性的作用。
