A STUDY OF THE DYNAMIC PROPERTIES OF THE HUMAN RED-BLOOD-CELL MEMBRANE USING QUASI-ELASTIC LIGHT-SCATTERING SPECTROSCOPY

A quasi-elastic light-scattering (QELS) microscope spectrometer was us ed to study the dynamic properties of the membrane/cytoskeleton of ind ividual human red blood cells (RBCs). QELS is a spectroscopic techniqu e that measures intensity fluctuations of laser light scattered from a sample. The intensity fluctuations were analyzed using power spectra and the intensity autocorrelation function, g(2)(tau), which was appro ximated with a single exponential. The value of the correlation time, T(corr), was used for comparing results. Motion of the RBC membrane/cy toskeleton was previously identified as the source of the QELS signal from the RBC (R. B. Tishler and F. D. Carlson. 1987. Biophys. J. 51:99 3-997), and additional data supporting that conclusion are presented. Similar results were obtained from anucleate mammalian RBCs that have structures similar to that of the human RBC, but not for morphological ly distinct, nucleated RBCs. The effect of altering the physical prope rties of the cytoplasm and the membrane/cytoskeleton was also studied. Osmotically increasing the cytoplasmic viscosity led to significant i ncreases in T(corr). Increasing the membrane cholesterol content and i ncreasing the intracellular calcium content both led to decreased defo rmability of the human RBC. In both cases, the modified cells with dec reased deformability showed an increase in T(corr), demonstrating that QELS could measure biochemically induced changes of the membrane/cyto skeleton. Physiological changes were measured in studies of age-separa ted RBC populations which showed that T(corr) was increased in the old er, less deformable cells.