FLUORESCENCE VITAL-MICROSCOPIC STUDY FOR CAPILLARY PERMEABILITY OF MACROMOLECULES

扩散和对流可能是骨骼肌中大分子通过毛细血管交换的主要驱动力。为了确定沿着单个毛细血管的这些渗透性参数，我们新开发了一种荧光生命显微镜，在该显微镜中，一对清晰的狭缝光束(宽度为28微米)聚焦在选定深度的组织区域，仅包括一条毛细血管。光束在由显微镜物镜焦面调整的交叉面上强烈激发荧光示踪剂(FITC-葡聚糖，分子量分别为40,000，70,000和150,000)。该显微镜被用来独立地定量大分子跨毛细管运动的扩散(P)和对流(V)成分。将该方法应用于血管扩张状态下的兔狭窄肌，证实了在毛细血管各区域的大分子跨毛细血管交换中，对流对扩散起主导作用。此外，本研究中获得的P值表明，静脉端的毛细血管壁对通过大分子的亲和力大约是真正毛细血管的40倍。

Diffusion and convection may be considered to be the main driving forces for the transcapillary exchange of macromolecules in the skeletal muscle. To determine these permeability parameters along a single capillary, we have newly developed a fluorescence vital-microscope, in which a pair of well-defined slit beams (28mum in width) were focused to cross at a chosen depth of the tissue region including only a single capillary. The beams excite the fluorescent tracer (FITC-Dextran, M.W.=40,000, 70,000 and 150,000) intensively at the crossing plane which is adjusted by the focal plane of the objective of the microscope. This microscope was applied to quantify the diffusive (P) and convective (V) components of the transcapillary movement of macromolecules independently. By applying this method to rabbit tenuissimus muscle under vasodilation, it was confirmed that convection is dominant to diffusion in the transcapillary exchange of macromolecules at all regions of the capillary. Furthermore, P values obtained in this study suggest that the capillary wall at the venular end has approximately 40 times more affinity to pass macromolecules than that at the true capillary.