Effects of ionic strength, serum protein and surface charge of membrane movements and vesicle production in heated erythrocytes.

Morphological changes and fragmentation of human erythrocytes heated at various rates through the spectrin inactivation temperature have been examined by cinephotomicroscopy. Most cells heated in 0.20 ionic strength buffered saline developed a wavy disturbance along the cell rim when heated. Vesicles developed from the crests of the growing waves within 0.3 s of the initiation of a wave when the heating rate was 1 degree C/s. At an ionic strength of 0.02, only 48% of the cells developed a wave outline. The average number of waves per cell was half that at 0.2 ionic strength. When the cell surface charge was reduced by neuraminidase treatment, only 12% of the cells fragmented. Bovine serum albumin or homologous plasma also reduced fragmentation. The dependence of the wave growth on ionic strength and surface charge was broadly consistent with theoretical predictions for the growth of a displacement instability on a low interfacial tension interface. Attention has been paid to the importance of bending energy in the development of the wave. Where wave development was suppressed, the morphological changes due to heating appeared to involve membrane internalization in the region of the cell dimple.