Greeson Jennifer N, Raphael Robert M
Rice University, Department of Bioengineering, MS 142, P.O. Box 1892, Houston, Texas 77251-1892, USA.
J Biomed Opt. 2007 Mar-Apr;12(2):021002. doi: 10.1117/1.2717499.
The biophysical properties and organization of cell membranes regulate many membrane-based processes, including electromotility in outer hair cells (OHCs) of the cochlea. Studies of the membrane environment can be carried out by measuring the orientation of membrane-bound fluorophores using fluorescence polarization microscopy (FPM). Due to the cylindrical shape of OHCs, existing FPM theory developed for spherical cells is not applicable. We develop a new method for analyzing FPM data suitable for the quasi-cylindrical OHC. We present the theory for this model, as well as a study of the orientation of the fluorescent probe pyridinium, 4-[2-[6-(dioctylamino)-2-naphthalenyl]ethenyl]-1-(3-sulfopropyl) (di-8-ANEPPS) in the OHC membrane. Our results indicate that the absorption transition dipole moment of di-8-ANEPPS orients symmetrically about the membrane normal at 27 deg with respect to the plane of the membrane. The observed agreement between theoretical predictions and experimental measurements establishes the applicability of FPM to study OHC plasma membrane properties.
细胞膜的生物物理特性和组织结构调节着许多基于膜的过程，包括耳蜗外毛细胞（OHC）的电运动。可以通过使用荧光偏振显微镜（FPM）测量膜结合荧光团的取向来开展对膜环境的研究。由于OHC呈圆柱形，为球形细胞开发的现有FPM理论并不适用。我们开发了一种适用于准圆柱形OHC的分析FPM数据的新方法。我们给出了该模型的理论，以及对荧光探针4-[2-[6-(二辛基氨基)-2-萘基]乙烯基]-1-(3-磺丙基)吡啶鎓（di-8-ANEPPS）在OHC膜中取向的研究。我们的结果表明，di-8-ANEPPS的吸收跃迁偶极矩相对于膜平面在27°时关于膜法线对称取向。理论预测与实验测量之间观察到的一致性确立了FPM在研究OHC质膜特性方面的适用性。
