Yuan Y, Chilian W M, Granger H J, Zawieja D C
Microcirculation Research Institute, Texas A & M University Health Science Center, College Station 77843-1114.
Am J Physiol. 1993 Aug;265(2 Pt 2):H543-52. doi: 10.1152/ajpheart.1993.265.2.H543.
This study reports measurements of albumin permeability in isolated coronary venules. The isolated microvessel technique allows the quantification of transmural exchange of macromolecules under tightly controlled physical and chemical conditions. Transvenular exchange of albumin was studied in isolated coronary venules during alterations in filtration rate caused by changes in intravascular pressure. The apparent permeability coefficient of albumin (Pa) at an intraluminal pressure of 11 cmH2O was 3.92 +/- 0.43 x 10(-6) cm/s. Elevating intraluminal pressure to 16 and 21 cmH2O increased Pa to 5.13 +/- 0.57 x 10(-6) and 6.78 +/- 0.66 x 10(-6) cm/s, respectively. Calculation of the true diffusive permeability coefficient of albumin (Pd) at zero filtration rate was 1.54 x 10(-6) cm/s. The product of hydraulic conductance (Lp) and (1 - sigma), where sigma is the solute reflection coefficient, was 3.25 x 10(-7) cm.s-1 x cmH2O-1. At a net filtration pressure of 4-5 cmH2O, diffusion accounts for > 60% of total albumin transport across the venular wall. Transmural albumin flux is very sensitive to filtration rate, rising 6.7% for each cmH2O elevation of net filtration pressure. At 11 cmH2O net filtration pressure, convection accounts for nearly 70% of net albumin extravasation from the venular lumen. We suggest that the isolated coronary venule is a suitable preparation for the study of solute exchange in the heart.
本研究报告了在离体冠状小静脉中白蛋白通透性的测量结果。离体微血管技术可在严格控制的物理和化学条件下对大分子的跨壁交换进行定量分析。在由血管内压力变化引起的滤过率改变期间，对离体冠状小静脉中白蛋白的跨静脉交换进行了研究。管腔内压力为11 cmH₂O时白蛋白的表观通透系数（Pa）为3.92±0.43×10⁻⁶ cm/s。将管腔内压力升高至16 cmH₂O和21 cmH₂O时，Pa分别增加至5.13±0.57×10⁻⁶ cm/s和6.78±0.66×10⁻⁶ cm/s。零滤过率时白蛋白的真实扩散通透系数（Pd）计算值为1.54×10⁻⁶ cm/s。水力传导率（Lp）与（1 - σ）的乘积（其中σ为溶质反射系数）为3.25×10⁻⁷ cm·s⁻¹·cmH₂O⁻¹。在4 - 5 cmH₂O的净滤过压力下，扩散占白蛋白跨静脉壁总转运量的60%以上。跨壁白蛋白通量对滤过率非常敏感，净滤过压力每升高1 cmH₂O，通量增加6.7%。在11 cmH₂O的净滤过压力下，对流占静脉管腔中白蛋白净外渗量的近70%。我们认为，离体冠状小静脉是研究心脏溶质交换的合适标本。
