Effect of Lidocaine and Epinephrine on Human Erythrocyte Shape and Vesiculability of Blood Cells

Figure 4

Suggested mechanism of erythrocyte shape change due to continuous interaction of exogenous substance with the membrane. Initially discocytic shape (a) transforms due to inclusions seeded by exogenous substance. If the inclusion resides in the outer layer, the area of the outer layer expands relatively to the area of the inner layer (the difference between the areas of the outer and the inner layer increases) and the membrane wrinkles outwards to attain echinocytic shape (c). If the inclusion intercalates into the inner layer, the area of the inner layer expands relatively to the area of the outer layer ( decreases) and the membrane bends inwards to attain stomatocytic shape (b). The process is promoted by increasing the number of inclusions while the erythrocyte shape transformation depends on the shape of the inclusion. If the inclusion is isotropic (axisymmetric with respect to the axis perpendicular to the membrane surface) and favors strongly curved membrane regions, membrane buds that form on the tips of the echinocyte spicules have spherical shape (h) while the invagination of the stomatocyte is axisymmetric with respect to the geometrical axis of the cell (d). If the inclusion is anisotropic (nonaxisymmetric with respect to the axis perpendicular to the membrane surface, so that its front view differs from its side view) and favors strongly curved cylindrical membrane regions, the membrane buds that form on the tips of the echinocyte spicules have tubular shape (i), while the invagination of the stomatocyte attains a peculiar pocket-like shape (e). The process of shape transformation is reflected also in the shape of the pinched-off EVs which may be spherical (j) or tubular (k) or in the shape of erythrocyte inner structures hinted by the shape of the closure at the cell surface (f, g), depending on the shape of the inclusions and their preference for the outer/inner membrane layer.