Bratzler R L, Chisolm G M, Colton C K, Smith K A, Zilversmit D B, Lees R S
Circ Res. 1977 Feb;40(2):182-90. doi: 10.1161/01.res.40.2.182.
125I-albumin was injected intravenously into normal conscious rabbits. The rabbits were killed after 10 minutes to 24 hours, and the descending thoracic aorta was excises immediately, opened longitudinally, rinsed, and frozen. Samples of frozen aorta were sectioned paralled to the intimal surface and washed with trichloroacetic acid (TCA) prior to counting. TCA-soluble tissue radioactivity slowly increased with time, suggesting that 125I was cleaved gradually from the labeled albumin within the aortic wall. At up to 4 hours, transmural concentration profiles of TCA-precipitable radioactivity had steep gradients near the intimal surface, moderate gradients near the medial-advential border, and were relatively falt in the middle of the media. After 24 hours, the steep intimal gradient had disappeared. Concentrations were otherwise comparable to those at 4 hours. The rate of accumulation of TCA-precipitable radioactivity was rapid initially (measurable concentrations were found throughout the media after only 10 minutes) and decreased with time. The results are consistent with entry of 125I-albumin into the media from both the luminal and adventitial sides. Approximate calculations indicate that the albumin mass transfer resistance associated with the intimal endothelium is about 1 order of magnitude greater than that associated with the media.
将125I标记的白蛋白静脉注射到正常清醒的兔子体内。在10分钟至24小时后处死兔子，立即切除胸降主动脉，纵向切开，冲洗并冷冻。将冷冻主动脉样本平行于内膜表面切片，并在计数前用三氯乙酸（TCA）洗涤。TCA可溶的组织放射性随时间缓慢增加，这表明125I在主动脉壁内逐渐从标记的白蛋白上裂解下来。在长达4小时时，TCA可沉淀放射性的跨壁浓度分布在内膜表面附近有陡峭的梯度，在内膜-外膜边界附近有中等梯度，而在中膜中部相对平缓。24小时后，内膜的陡峭梯度消失。其他方面的浓度与4小时时相当。TCA可沉淀放射性的积累速率最初很快（仅10分钟后在整个中膜中就发现了可测量的浓度），并随时间下降。结果表明125I标记的白蛋白从管腔侧和外膜侧进入中膜。近似计算表明，与内膜内皮相关的白蛋白传质阻力比与中膜相关的阻力大约高1个数量级。
