Erythrocytes are widely used as a model system for membrane studies due to their relatively simple structure (they lack nuclei and organelles having only the plasma membrane), their convenient experimental manipulation and availability. However, the high hemoglobin content inside the red blood cells may be a problem for the use of fluorescent membrane probes. Hemoglobin content inside erythrocytes is around 20 mM and the molecules near the inner membrane surface would be the responsible for the quenching of fluorescent dyes such as 1,6-diphenyl-l,3,5-hexatriene (DPH) and 12-(9-anthroyl) stearic acid (AS).