Determination of time-dependent shape changes in red blood cells

A kinetic method for detecting changes in red blood cell shape with time re solution on the order of seconds is described. The definition of shape inde x (SI) and the experimental conditions under which the measurements should be conducted are given, and the relationship between SI and morphological i ndex, which is often used to quantitatively assess red blood cell morpholog y, is established. Further, we show that the method can be used to assess s hape changes under a variety of experimental conditions known to cause majo r perturbations in the morphology of red blood cells (such as addition of l ysolecithin or chlorpromazine) and to detect changes in shape during chemic al fixation for observation with microscopy. We report here that the abilit y of glutaraldehyde to fix red blood cells without additional alteration in shape strongly depends on the morphology that is being fixed and the initi al state of the cells.