Severs N J
Eur J Cell Biol. 1981 Oct;25(2):289-99.
Glutaraldehyde-fixed rabbit myocardium was treated with the polyene antibiotic, filipin, which binds specifically to sterols in membranes, producing distinct 25 nm-diameter deformations. These deformations (lesions) serve as labels for the presence of cholesterol-rich membranes and membrane domains. The distribution and density of filipin-induced lesions was examined in the plasma membranes of cardiac muscle and capillary endothelial cells by freeze-fracture electron microscopy. In the exposed fracture faces of endothelial plasma membranes, more than 99% of the surface area was covered with lesions, whereas about 90% of the plasma membrane area in the muscle cells remained unaffected by the treatment. Muscle cell plasma membranes revealed a patchy response; the lesions occurred in clusters which were separated by interconnecting expanses of unaffected membrane. Endothelial cell plasmalemmal vesicles, and muscle cell caveolae and transverse tubules displayed the same response to filipin as neighbouring areas of plasma membrane. However, gap junctions and desmosomes of the muscle intercalated disc membrane, and coated pits in both cell types were completely resistant to filipin treatment. These results provide evidence that the plasma membranes of the two cell types possess markedly different overall cholesterol levels, and that each has a characteristic pattern in the planar distribution of cholesterol.
用多烯抗生素制霉菌素处理戊二醛固定的兔心肌，制霉菌素能特异性结合膜中的固醇，产生直径为25纳米的明显变形。这些变形（损伤）可作为富含胆固醇的膜和膜结构域存在的标记。通过冷冻断裂电子显微镜检查了制霉菌素诱导的损伤在心肌和毛细血管内皮细胞质膜中的分布和密度。在内皮细胞质膜暴露的断裂面上，超过99%的表面积被损伤覆盖，而肌细胞中约90%的质膜面积未受该处理影响。肌细胞质膜呈现出斑驳的反应；损伤成簇出现，被未受影响的膜的相互连接区域分隔开。内皮细胞质膜小泡、肌细胞小窝和横小管对制霉菌素的反应与相邻的质膜区域相同。然而，肌闰盘膜的缝隙连接和桥粒以及两种细胞类型中的有被小窝对制霉菌素处理完全有抗性。这些结果证明，两种细胞类型的质膜总体胆固醇水平明显不同，并且每种细胞在胆固醇的平面分布上都有其特征模式。
