Osmotic deformation of red blood cell ghosts induced by carbohydrates

The osmotic response of bovine red blood cell ghosts to a series of sugars is studied by light scattering. The sealed and right-side-out ghosts are prepared by the procedure of Steck and Kant (Steck, T.L. and Kant, J.A. (1974) Methods Enzymol. 31, 172-180), swollen in a hypotonic phosphate-buffered saline solution and their size and shape determined by elastic and quasielastic light scattering. Different carbohydrates are then added to the suspending medium in order to examine the osmotic responses, and the osmotic deformation of ghosts is shown to be spherically symmetric. Having thus established the deformation behavior, we then rank the osmotic activity of a carbohydrate relative to a standard, i.e., raffinose. It is found that the osmotic response of the ghosts to sucrose is about the same as that to raffinose, and the response to the smaller carbohydrates simply follows the number of carbons in various sugars; glucose and fractose are about 1.7 times less effective than raffinose, and pentaerythritol and meso-erythritol are 2.3 times less effective. Glyceraldehyde, which is 3.6 times less effective than raffinose, is the least effective sugar analog among those that we have tested.