Hise M K, Mantulin W W, Weinman E J
Am J Physiol. 1984 Sep;247(3 Pt 2):F434-9. doi: 10.1152/ajprenal.1984.247.3.F434.
The physical state of rat renal brush border and basolateral membranes was examined using the technique of electron spin resonance. As estimated from the order parameters of both 5- and 12-doxyl spin-labeled phosphatidylcholine, the brush border membrane was significantly more ordered than the basolateral membrane. To confirm these findings, fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene was studied. Fluorescence anisotropy at 25 and 37 degrees C was significantly greater in the brush border membrane when compared with the basolateral membrane. The relative contribution of the lipid component to this difference was examined using multilamellar liposomes prepared from lipid extracts of these membranes. Fluorescence anisotropy in the brush border membrane lipids was significantly greater than that in the basolateral membrane lipids at both 25 and 37 degrees C. Compositional determinants of fluidity were examined in both membranes. Factors that may contribute to the more fluid state of the basolateral membrane include 1) a greater lipid-to-protein ratio; 2) a greater ratio of phosphatidylcholine to sphingomyelin; and 3) a tendency toward shorter-length fatty acyl chains.
利用电子自旋共振技术检测大鼠肾刷状缘膜和基底外侧膜的物理状态。根据5-和12-二氧代自旋标记磷脂酰胆碱的序参数估计，刷状缘膜比基底外侧膜的有序程度明显更高。为证实这些发现，研究了1,6-二苯基-1,3,5-己三烯的荧光偏振。与基底外侧膜相比，刷状缘膜在25℃和37℃时的荧光各向异性明显更大。使用从这些膜的脂质提取物制备的多层脂质体研究了脂质成分对这种差异的相对贡献。在25℃和37℃时，刷状缘膜脂质中的荧光各向异性均明显大于基底外侧膜脂质中的荧光各向异性。研究了两种膜中流动性的组成决定因素。可能导致基底外侧膜流动性更高的因素包括：1）脂质与蛋白质的比例更高；2）磷脂酰胆碱与鞘磷脂的比例更高；3）脂肪酸酰基链有较短长度的趋势。
