Abstract
The temperature dependency of the membrane particle reorganization, which is probably an indication of lipid phase separation, was quantitatively examined on the outer alveolar membrane of Telralzymena cells by freeze-fracture electron microscopy. The degree of particle aggregation (particle density index, PDI) determined by measuring the particle number per square micrometer on the fractured membrane was compared with the results of fluorescence polarization of 1, 6-diphenyl 1, 3, 5-hexatriene (DPH) embeded in the membrane. Fluidity of the outer alveolar membranes was modified by treating with an anesthetic, methoxyflurane or exogenous ergosterol. These altered membranes showed decreases of both onset temperature and degree of phase separation as examined by freeze-fracture electron microscopy, indicating an increase of fluidity which was confirmed by data of fluorescence polarization of DPH-labeled membranes. These results suggest the possibility that the PDI method by freeze-fracture electron microscopy may be useful for estimating fluidity changes of membranes.
