The influence of temperature and incubation time on deformability of human erythrocytes

Human erythrocytes have been heated and stressed in a novel and controlled manner using rectangular microcapillaries. Heated cells attached to the capillary wall were stressed by liquid flow. Under particular conditions of stress, temperature and incubation time the body of the cell could be pulled in the flow, retaining a connection with the glass by means of a narrow process or tether. The tethers appear as: regularly beaded, irregularly beaded or without beads depending upon the incubation conditions. We have outlined the incubation regimes necessary to achieve these different responses in the temperature range 48--55 degrees C. The cells become less deformable as the incubation is continued beyond an optimum time. The behaviour of the tether is compared with that of a viscoelastic liquid. Circular dichroism studies of ghost membranes show that the denaturation of membrane proteins is partially reversible when incubation times are similar to those required to bring about a loss of deformability.