Bassingthwaighte J B, Kuikka J T, Chan I S, Arts T, Reneman R S
Am J Physiol. 1985 Jul;249(1 Pt 2):H141-9. doi: 10.1152/ajpheart.1985.249.1.H141.
Multiple indicator-dilution experiments were done to compare the transcapillary exchange of tracer amounts of L-[14C]ascorbate and D-[3H]glucose (against an intravascular reference 131I-albumin) in Ringer-perfused (5 mM glucose) isolated rabbit hearts. The indicator-dilution curves for the two were virtually superimposed over the first 40-80 s. Estimates of the capillary permeability-surface area products, PSc, were the same, 2.3 +/- 0.7 (SD) ml X g-1 X min-1 (n = 18), in accord with the coincidence of their instantaneous extractions. The similarity of glucose and ascorbate permeabilities is explained by the similarity in molecular weights and passive diffusivity, their lipophobic nature, and the paucity of carrier-mediated endothelial transport for either molecule. The data were analyzed via a model composed of aggregates of spatially distributed capillary-tissue units (capillary blood, interstitium, myocytes) accounting for the heterogeneity of regional flows. The interstitial volumes in this preparation are enlarged, 0.30 +/- 0.04 ml/g. There is substantial entry into myocardial cells, the cell permeability-surface area products being approximately 2-3 ml X g-1 X min-1 for ascorbate and glucose. The estimated volumes of interstitial and intracellular space, 0.30 and 0.47 ml X g-1 X min-1, reflect interstitial edema and are very close to measured values, giving reassurance concerning the methods of modeling analysis.
进行了多次指示剂稀释实验，以比较在林格氏液灌注（5 mM葡萄糖）的离体兔心脏中，微量示踪剂L-[14C]抗坏血酸和D-[3H]葡萄糖（相对于血管内参考物质131I-白蛋白）的跨毛细血管交换情况。在最初的40 - 80秒内，两者的指示剂稀释曲线几乎完全重叠。毛细血管通透性-表面积乘积（PSc）的估计值相同，为2.3±0.7（标准差）ml·g-1·min-1（n = 18），这与它们瞬时提取率的一致性相符。葡萄糖和抗坏血酸通透性的相似性可以通过分子量和被动扩散率的相似性、它们的疏脂性质以及两种分子载体介导的内皮转运缺乏来解释。数据通过一个由空间分布的毛细血管-组织单元（毛细血管血液、间质、心肌细胞）聚集体组成的模型进行分析，该模型考虑了区域血流的异质性。该制剂中的间质体积增大，为0.30±0.04 ml/g。有大量物质进入心肌细胞，抗坏血酸和葡萄糖的细胞通透性-表面积乘积约为2 - 3 ml·g-1·min-1。估计的间质和细胞内空间体积分别为0.30和
